13th October 2024
When trojan-dumping the IGS027A on the recently arrived mahjong boards, one of the most important criteria for it to happen is the board
must be working. With that in mind, one board (#7 in my list) is dead and only shows crap on the screen. Here's a pic of the
board as it arrived....
There are a bunch of 100% identical PCBs in this batch and the 027A chip could easily be transplanted to a working board for trojaning. But
maybe it'll be fun to repair this so here we go ;-)
The board is really hammered. Not only has there been substantial nicad (Varta) battery leakage but the whole board is really nasty and
dirty on BOTH sides of the board! I cleaned off most of it with a small paint brush before even touching it. These IGS mahjong boards are
relatively simple. There is a single 22MHz oscillator (checked working) and a T518 reset IC in TO92 package (also checked working). Because
of the secret custom IGS027A chip and low chip-count there's not a lot of simple stuff that can be checked. However power is important, not
just from the JAMMA connector. These boards also have a small regulator that provides 3.3V to the IGS027A and IGS031 custom and possibly
other stuff too. This one was only outputting 2.667V despite having a 5.03V input voltage so it must be bad. I swapped it out for a working
part and powered on the board.
The voltage on the regulator measures 3.3V now and it's sort of working hehe! This message means the IGS027A microcontroller (which is the
main CPU on these boards) can't see the program ROM. More importantly the 027A chip is good. This text comes from the internal ROM in the
IGS027A MCU. Note not every 027A chip shows text, some show only garbage but with this one we get to see the date and time of the software
compile. The later year (2004) will be the release date of this game and the V213CN will be the very first main program version using this
specific internal ROM software.
The main program ROM socket was also hammered and corroded to shit so I swapped it for a new one....
I beeped out all the connections on the ROM to the 027A and everything joined except one pin, OE (pin 20). That connects to a nearby
surface-mounted 32kBx8-bit SRAM on pin 20 (CS) which was a static high. CS is an active low signal and also an input so it must come from
somewhere else. Tracing it reveals CS comes from a 74HC132 chip near the battery, pin 8.
Let's check the datasheet....
This is a Quad 2-Input Positive NAND Schmitt-Trigger. The datasheet shows pin 8 is 3Y output. The inputs are pin 9 (3A) and pin 10 (3B). Pin
9 is tied to a resistor pulled up to VCC. Pin 10 is tied to the IGS027A pin 93. So for some reason the MCU is not sending the OE signal to
the ROM. I checked the 74HC132 area for damage and continuity but it all looked good. Only 1/4 of this chip is used, the
other 3 input pairs are unconnected. Then I noticed this nearby chip....
LOL! It's had its ass blown off LOL! This is a ULN2004 Darlington Transistor Array connected to some of the inputs. On mahjong panels some
buttons have a globe inside to light them up or flash so my guess is one of the 12V globes shorted to the input data line and blew up this
chip. For now I'll just remove it in case it's causing an issue. The game will work without it but some of the inputs won't work.
But I'm sure whatever was connected to this chip is dead. Let's check the datasheet for the pinout....
Ok so the inputs are on pins 1-7, outputs on pins 10-16 and 12V is on pin 9. Tracing the chip reveals the outputs go to the JAMMA connector
(to drive globes or something similar), the inputs come from the 8255 Programmable Peripheral Interface (PPI). This chip most likely
connects directly to the 027A.
Let's check the datasheet....
Pins 34-27 are D0-D7 and do connect directly to the 027A. The ULN2004 inputs connect to Port A (PA0-PA7) on the PPI. I decided to pull and replace the PPI as there's no easy way to test it....
Replacing the PPI didn't change anything. I suppose I should look at the RAMs lol! The 2x DIP28 RAMs are 8kBx8-bit and I know from other
working boards that this RAM is the video RAM connected to the IGS031 custom. There's only one other RAM, a MT62C256 32kB x8-bit SRAM. This
chip is the one with the high CE pin and has all active data pins but maybe there's a shared data bus and it looks active but actually isn't. It
can't actually be outputting anything as CE is high (not enabled). I pulled the chip....
I don't have an easy way to test these SOP28 RAMs in my chip tester as there's no DIP-SOP socket adapter for this package (no ROMs were ever
made in this 300-mil SOP28 package). I could surface mount it to a small bare pads SOP28 PCB to DIP adapter I have but that's just annoying.
However for this scenario I have a working random game board that uses this same RAM and I use it for testing. I previously removed one of
the chips and cleaned off the pads, then I simply hold the RAM in place, push down hard and power on. If the game works the RAM is ok since
that RAM I removed is part of the main program RAM. If no boot the RAM is bad. So I did that and.... no boot! I swapped out the RAM for
another one on the mahjong board, powered on the board and....
Hehe!!! It's working!!!!!! And of course the CS pin on that RAM is now *very* active :-)
Ok, so if you've been paying attention to recent game additions in MAME you'll see this is actually the same game as the just added 'cjddz'
(Chaoji Dou Dizhu). Hmmm, the game was listed as 'Lucky Pao De Kuai' and Dyq informed me the seller sold it to little0 as that game and
perhaps little0 was misled on purpose by the seller. Personally I believe the seller is like most sellers (completely clueless LOL!) and
being that it wasn't working there was no way to check it.
Ok well we have a different version as this one shows as V219CN in the test screen.... yes, that's a MAME screenshot on the last pic above ;-)
The game is working but there's no sound. I added a credit and still no sound, just crackles and hiss. Looks like there's a sound fault
hehe!
I was going to check the volume pot but it's fu----. No wait, let's try to educate the public about how this should be explained by using a
word that a local friend used the other day. This word needs to be used more often. The word is 'munted'. For example if a volume pot is
missing the top, it's munted. If you drop a ROM on the floor and step on it... you guessed it, that ROM is munted. It's the kind of word you
can use when the mrs is nearby and she won't know what you *really* mean hehe! So now that you have all been suitably educated about
infrequently used words in the Australian language we'll continue with the repair ;-)
Umm yeah that needs to be replaced....
I turned the nice new pot, still no sound. I touched the amp IC with a wet finger and it makes a clicking noise so the amp seems to be ok.
The sound chip on this board is the low-end Oki M6295. This is an ADPCM Sample Player IC. I wanted to see if the chip was doing anything, to
check if the fault was on the generation (i.e. digital) side or on the output (i.e. amp) side. Let's check the datasheet....
There are several signals that are of importance when checking to see if the M6295 is good. Under normal operation almost all of the pins
will be actively flashing low/high continuously.
- Pin 2: Read, active low
- Pin 3: Write, active low
- Pin 4: Chip Select, active low. Signal is syncronised with read and write.
- Pin 5,6: Clock, must have an active clock signal on it
- Pin 7: Sample Rate. Most arcade boards have this tied high (VCC). A low setting here (tied to GND) sets a lower sample rate.
- Pin 8: Reset, should be high for normal operation
- Pins 9-16: D0-D7, tied to the external ROM. Must be active
- Pins 18-35: A0-A17, tied to the external ROM. Must be active, but depending on the ROM size some of the upper address pins may be tied to gnd or vcc or floating (i.e.
not connected)
- Pin 36: Audio Output (named DAO). Internally this is connected to the digital to analog converter (DAC), hence the pin name DAO (DAc
Output). This should be checked with an oscilloscope as it can show as an inactive low if checked with a logic probe. In some cases
(depending on the circuit) a logic probe with a piezo speaker can 'hear' the analog audio coming out of the chip.
- The remaining eight pins 37-44 are input registers for phrase selection. From a repair point-of-view they should be active and that's all
that matters unless the chip is doing strange things. If there was a problem with these pins it could be a very deep rabbit hole to go
down so for now I'll ignore those pins.
So checking the chip, the read/write pins are active (good), clock is 1MHz (good, master OSC 22MHz/22), reset is high (good), chip select is high
(not good), data pins are inactive (not good). Basically this chip is not selected (CS must be low), hence the reason why it's not active. I
traced CS (pin 4) and it goes to a nearby logic chip 74LS245 pin 19. This is also a chip enable and is an input so this signal must come
from somewhere else. Going all over the board I can only see one other place where this signal goes... to the IGS031 custom chip. Hmmm, that
has to be the source of the CS signal and might be bad news, but I find it difficult to believe that the IGS031 is bad since the graphics
are fine. Maybe something is pulling that line up to VCC. I powered off/on and for a brief moment there was a pulse on the CS pin,
then just a static high. An easier way to cycle the board is to reset it using the reset switch. This switch has been put there to clear the
NVRAM for various reasons but we can use it to easily reset the board without having to constantly power-cycle the board....
These boards have a battery that holds power to a RAM (hence it is called a non-volatile RAM or NVRAM). On this board that RAM is the RAM
tied to the IGS027A (the same one I changed earlier). Potentially, if the contents of the RAM was corrupted it could cause a no-boot
situation (exactly like any modern PC if the CMOS is corrupted) so this reset switch also allows clearing of the NVRAM data. What this
actually does is disconnect the battery power from the RAM and shorts the VCC pin to ground. There are some diodes, a transistor and some
resistors to prevent a dead short if the switch is pressed while the board is powered. In fact it's perfectly safe to press the switch while
the board is powered and the game will simply reset back to the title screen attract mode with no credits. This makes it a nice way to exit
a game and see the title screen, very helpful in a repair situation if credits have been added. Without the NVRAM clear function, a board
with active credits that is reset will continue from where it was previously as there would be no way to clear the current state of the RAM.
The connected RAM is doing a LOT more than just holding some settings, this is the work RAM for the IGS027A. So while resetting the board
multiple times I probed the data pins but saw nothing on the probe but the fact that I saw one pulse on CS means the IGS031 is
trying to send the CS signal. I lifted the connected pin on the nearby 74LS245 pin 19 as it's a relatively common fault for a pin next to
the VCC pin to short or partially short to VCC.....
Unfortunately no change there, CS is still stuck high. I suppose it's possible the M6295 is bad so I pulled it....
Then I powered on while probing the CS pin on the board. WOW!!! Now CS is active hehe!! I replaced the Oki M6295 with a working chip taken
off a junk board. This one is actually an AD-65 which is a common clone often seen on cheap bootlegs but is 100% compatible and can be used in
place of the Oki M6295. With the chip replaced I powered on. CS is pulsing but no sound??? Oh, I forgot I still have pin 19 lifted on the
nearby 74LS245. This 245 is connected to the previously mentioned input register pins. The other side of the 245 is connected to the 027A,
031, work RAM, PPI and a bunch of other chips.... this is the CPU data bus. With pin 19 of the 74LS245 resoldered down the sound is working!
:-D
The sound is really bad, grainy and there's not a lot of volume. Maybe I've been spoiled by having access to a lot of high quality boards
over the years and this one is just crap lol! There's a bunch of caps in the sound section and they are probably all out of specification. I
pulled them and tested, finding that most of them were 20-30% out of tolerance but a couple were within 10%. I changed them all anyway but
there was no change to the music and it still sounds nasty. I guess that's just how it is on these boards. The in-game sounds are fine but
the speech and music is very low quality, which I suppose is to be expected from this low-cost low-end board.
If you are paying attention you'll notice there's one cap missing. The two caps in the middle of that section were 470uF but connected in
parallel, + to + and - to -. When capacitors are wired in parallel the total capacitance is simply all of the capacitances of each cap added
together. So the original capacitance would have been 940uF. I don't have 470uF caps in stock so I put in a 1000uF which is near enough the
same thing. The other caps near the edge connectors are still the old ones... yeah they will be bad too but these are power caps connected
between VCC and GND and don't affect functionality. Any good power supply can supply enough current without requiring additional caps at the
connected device. In fact some of these boards that arrived have bulging caps and everything is still working fine. I could change them but
these are essentially scrap boards just for dumping so I'm not going to waste good caps making a junk board look better then have it sit on
a shelf for the rest of its miserable life ;-)
Anyway, here's a pic of the full board transformed from a dirty non-working piece of crap to a clean and fully working piece of crap ;-)
MAME screenshot updates (in # order) for this recent batch of mahjong games will be shown here. Come back later for more pics when things are working in MAME.
#2 (from the list below) in MAME, thanks to quick work by Osso.... Long Hu Zheng Ba 4 (version V203CN)
#3 and #7 (from the list below) in MAME, thanks to quick work by Osso.... Super Dou Di Zhu (version V219CN)
#5 (from the list below) in MAME, thanks to quick work by Osso.... Super Dou Di Zhu (version V217CN)
#9 (from the list below) in MAME, thanks to quick work by Osso.... Super Dou Di Zhu Liang Fu Pai (version V109CN)
#10 (from the list below) in MAME, thanks to quick work by Osso.... Super Dou Di Zhu Plus (version S300CN)
#11 (from the list below) in MAME, thanks to quick work by Osso.... Super Da Man Guan 2 (version V754C, different encryption. 1st version of this game with easier gameplay)
Keep an eye on the game list below for minor (text only) updates.
12th October 2024
With the recent success of IGS027A trojaning, the flood gates have opened up for a lot more of the same so it was only a matter of time
until the next batch of Mahjong boards arrived heh! Thanks again to Dyq and little0.
All of these boards use the same hardware that is already fully emulated in MAME so all of these will eventually have working emulation.
These are the game titles below. Refer to the pic above for the numbers to identify the boards.
Where applicable the IGS027A sticker is listed for documentation purposes.
Strike-through means they have been 'processed'.
Red text will have strike-through when trojaned.
1. Long Hu Zheng Ba 1 or 2? 2. Long Hu Zheng Ba 4 (flower match version) (F12) 3. Super Dou Di Zhu (N1). Same as cjddz in MAME but V219CN 4. Long Hu Zheng Ba 1 or 2? 5. Super Dou Di Zhu (S12). Same as cjddz in MAME but V217CN 6. Super Tuo La Ji Plus (poker game) (T5) 7. Super Dou Di Zhu (B6) (was Lucky Pao De Kuai). Same as cjddz in MAME but V219CN 8. Long Hu Zheng Ba 3 Upgrade Version'Super-Special-Secret-Shit' Unknown CPU internal ROM 9. Super Dou Di Zhu Liang Fu Pai (Two Deck Of Cards)(J1) 10. Super Dou Di Zhu Plus (A9). Same as cjddzp in MAME so already dumped 11. Super Da Man Guan 2 (first/easiest version). Same software version in MAME but this one has different encryption 12. Long Hu Zheng Ba 3(U10) 13. Ming Xing San Que Yi (Star 3 Lack 1, a 4-player mahjong game)(A8)
#13: This will be interesting, looks like IGS PGM hardware ;-)
Running the trojan was also interesting. Initially the data just came out garbage. It was running ok but only outputting crap because the
serial port is timing sensitive and the code is expecting the 027A clock to be the standard 22MHz. However on this board the 027A clock is
33MHz. I was told to try different baud rates. I tried them all but that doesn't work because the CPU is outputting at some baud rate that
is not a standard serial port rate, so the output is just grabage. I solved it by looking outside the square. No point trying to fight it,
just give it what it wants.... so I removed the oscillator and put in a 22MHz one and the trojan worked perfect lol! Funnily enough the game
actually works fine with that same 22MHz oscillator so it's a bit of a mystery why the 33MHz oscillator was used.
#8: This is using a secret CPU. The 027A is not there and instead it's a totally unmarked QFP128 chip. I suspected it's a clone in a different
package so the trojan was written for the 027A and I ran it on the board. It appeared to be working and the data bus was active and acting
the same way as the other trojans. At this point the chip pinout was unknown which means the location of the serial port was also unknown or
maybe it didn't even have one at all. While the trojan was running I probed the pins and found the data stream on one pin was exhibiting the
same behaviour as a 027A serial port pin. I hooked up the serial wires and it came out perfect first try hehe!! They made 4 big mistakes....
A) They used the same PCB number and part layout as one of the other boards that uses a standard 027A that I dumped in the last batch of
mahjong boards, B) They didn't mark the chip with anything, just left it blank so it looks suspect/secret, C) They made the chip
code-compatible with the 027A, D) They left the serial port enabled. LOL!
This thumbnail is real life size to the actual chip. Pin spacing is 0.5mm and the wire connected there is 0.05mm diameter ^_^
#10: One of the Super Dou Di Zhu games is already dumped and running in MAME but the sticker on the 027A chip is different. The text strings
in the internal ROM on my board matches the one in MAME when the program ROM is removed. This proves there's some random guy at IGS with a
roll of random stickers just slapping them onto the chips randomly to make it look like he has an important job cataloging software
revisions, or obfuscating software revisions making it look like the programmers are doing something when actually they are off playing
arcade games somewhere or eating out at the local hamburger joint LOL! I'm sure there will be more trickery revealed soon when some of the
other 027A internal ROMs are trojan-dumped... no more secrets ^_^
In other news a couple of Jakks TV Pacman games arrived....
This has 12 games in 1 and is actually pretty good when viewed on an old-school CRT TV but looks really terrible on my LG 4K LCD TV. One
nice feature is Pole Position controls. I originally thought the steering was not working but it turns out the top red ball knob is self-centering and rotates like a wheel
:-)
Both units are identical and contain a small PCB with two epoxy blobs. As far as dumping goes, we'll see how it pans out over the next few weeks / months / years ;-)
7th October 2024
A local friend asked me to look at a Data East Captain America and the Avengers PCB....
He bought a small cab (called a "Lowboy", made by LAI in the 80's and 90's) which had this board inside. The seller posted pics on a
for-sale site and showed it working perfectly. Seller said they didn't play it anymore so moved cab into the garage. The cab has a PCB mount
inside and the board sits upright in the holder against the inside of the cabinet. There would be no way, for example, for this to
happen....
The top side is clean but the bottom of the board is covered in dirt.... like it's been sitting upside-down in someone's garage for ~5 years lol!
Yeah buddy, working perfectly lol!
So the dirt proves the seller knew it was faulty and pulled the board out hoping that just staring at it would fix it lol! It's clear no one
has touched the board so at least the seller had enough working brain cells to realise he is clueless and not mess with it.
This is a really expensive and rare board nowadays so it has to be fixed.
The game is working but the sprites are messed up....
Now this is not your usual sprite fault where lines go through the sprites, this is a selection issue where the wrong parts of the sprite
are displayed. As the player sprite moves those missing parts show up randomly at different (wrong) locations but it's a little bit
difficult to capture that with just static pics.
The sprite section is this corner of the board....
There doesn't appear to be any sprite RAM on this board. I went over the entire board and piggybacked all the RAMs but nothing affected the
sprites. The RAM near custom chip #56 is the background RAM. I'm assuming if there is sprite RAM it's inside one of the custom chips.... not
a good sign for longevity of a board. I first had to check the sprite ROMs but on this board they are all soldered in. This brings back
memories of when I dumped one of these boards for MAME back in 2002 to fix the dump that was previously done badly by someone with not
enough knowledge and/or not the correct equipment.... Wow 22 years ago!! After some hours all 4 ROMs were removed and dumped.
For reference, these are the sprite ROMs, read as uPD27C8000 or TC578200 (42 pin)....
man-06.17a CRC32 = a9a64297
man-07.18a CRC32 = b1db200c
man-08.17c CRC32 = 28e98e66
man-09.21c CRC32 = 1921245d
Unfortunately it wasn't going to be that simple as all the ROMs read ok compared to MAME archives.
While pulling the ROMs I noticed this strange glob of stuff between two of the ROMs....
Initially I thought maybe something died here hehe! But no, this is conformal coating that has been applied to a trace that was 'dented'. I
removed it and it was not broken, but in the past something hit that section of the board and put a dent there and someone covered it
up. I really, really didn't want to change the custom sprite chip because I didn't have spares except on other working Data East boards
so I needed to look at all the other stuff first. There's a bunch of logic chips (both through-hole and surface-mounted types) connected to
the ROMs and custom chips. Probing with logic probe didn't reveal anything that looked dead. This is fairly common where there are shared
buses so a chip can be dead and not outputting but appears to be working and the data being checked is actually coming from another chip on
the same bus. So I pulled and tested each chip (more hours) and eventually found the 74LS375 at location 21B was bad....
Unfortunately this logic chip is not common and I didn't have a spare in my parts box. I knew I had one on a junk Gaplus board but it would
be a very old weathered chip. I removed it and tested in my IC tester and it passed but the legs were crumbling. It's one of those Texas
Instruments chips were the legs were coated with silver and for some reason this reacts with the copper leg and causes it to turn black,
become weak then fall off. This chip was no different and one leg was really weak and was almost falling off. I carefully put it into a
socket to help support it and soldered it into the board.....
I'm thinkng this is it and it's going to be fixed. I powered on and sh!t, not fixed, actually no change at all! I pulled the logic chip and
re-tested it in my IC tester and it didn't pass now! Of course that flakey leg fell off and was still in the socket lol! Well this chip
would not have been good enough to leave on there permanently anyway. Double sh!t.... where am I going to find another one??? So then I
spent the next couple of days looking through junk boards for a 74LS375. Finally found one and put that in....
Sh!t again, not fixed, but different, possibly slightly better....
Well that leaves me with no choice so I pulled the sprite chip (DECO chip #52)....
I replaced it with another #52 custom chip (reluctantly) taken off another Data East board and that fixed it :-)
25th September 2024
A clean Irem Legend of Hero Tonma (M72 hardware) came in for repair....
The board is dead and only shows a white screen with some random colored blocks. The owner says he bought it off a local guy in a cabinet
and it was shown working and the guy just moved the cab to the front of the house and left it there to be picked up later. Hmmm, sounds
suspect that a game that was working and left untouched is now not working lol! There are quite a few M72 repair logs on the net but it
seems that no one has any clue how these boards work. The quick/parroted noob answer is change the RAM and that's about it hehe! It's not
surprising as these are extremely difficult to work on due to having 3 boards stacked together which must be in place for the game to work
so removing them to probe for faults is not possible. Together with all the special custom chips it makes this board basically just plain
annoying! If you are thinking of buying an M72 board (which is 35 years old!) you had better be damn good at board repairs, otherwise save
yourself the problems and just use MAME running on any of the random chinese Android boxes that are available now or a Pi4. Any simple
joystick/button game works perfect and when put inside an arcade cab the experience is identical... or actually better since now you can
choose any one of hundreds or thousands of games to play, all for free! Collectors will frown and think they are elite and their boards are
indestructable but they are wrong! One day you will see the light when your board dies and is worthless ;-)
Schematics for M72 are available but the ROM board type is the simple one containing just ROMs, whereas Legend of Hero Tonma has a larger
board and a bunch of logic, a PAL and an i8751 MCU. M72 has several of the nasty known-junk Toshiba TMM2063 8kB RAMs so the first port of
call is to remove and replace them with good RAMs. I pulled and tested them and they actually passed lol! Replacing them didn't do anything and
the board is still dead. Checking the CPU (uncommon NEC V30) clock and reset shows they are present. The Z80 controls the audio and
while the clock was present the reset was only low. I figured maybe the CPU is waiting for a response from the Z80 so I ended up wasting
some time trying to figure out why the Z80 didn't reset at power-on. Don't waste time on this, I'll explain why....
Short Answer: The Z80 reset is CPU-controlled and does not actually reset until the game title screen shows, where you'll hear a little
'click' noise at that time when the Z80 starts up. The game will actually boot up without the Z80.
Long Answer:
The schematics show a BRQ signal (comes from a 74LS174 at 1D pin 2) going into a 74LS02 Quadruple 2-Input Positive NOR Gate at 7C (IC52),
the output on pin 1 was floating and measured around 1.4V. That output goes to a transistor (PCB has D945, schematic shows 2SC1815, both
compatible), an electrolytic cap (connected to ground on the negative side) and a 22k resistor pulled up to VCC and a couple of connected
470 ohm resistors. This is the Z80 auto-reset circuit (or so I thought) and the 74LS02 output pin 1 was floating despite having lows on both
input pins 2 and 3 (74LS02 truth table shows low+low=high output). I pulled and tested the 74LS02 and it passed in my chip tester. I
replaced it anyway and now the output was high!! I figured that would fix the issue but the Z80 still does not receive a high on the reset
pin as it's not a direct connection from the LS02 pin 1 to the Z80 reset pin. I pulled the transistor (TR3) and it tested ok and the
resistors and capacitor also tested ok. The schematic shows that same reset line goes to another location labelled 'SRESET' on the right
side of the schematic but I can't find that signal on the schematic. I traced the entire board with multimeter beep test but it simply does
not exist! Rather than continue to flail around wasting time on a nothing-burger I decided to move onto looking elsewhere for any other
issue.
The ROMs read and compared good against MAME archives. Piggybacking the main V30 program RAM (2x 43256 RAMs) didn't help either. After
checking a few logic chips I noticed some buffer enable pins coming from the ROM board PAL (which was not outputting anything) so I got the
existing dump off the net, programmed it to a GAL16V8 and plugged that into the socket but it made no difference. BTW, the LOHT PAL on the
ROM board is the same one from Image Fight and actually works fine (label "IF C-3F-" = "TOM C-3F-", tested working later). I removed the top
ROM board and probed around looking for any logic chip that had working inputs but dead outputs. There were actually lots and lots of chips
like that, and even some that were very hot. The thing is those chips were mostly bus buffers where the enable pin was high so the chips are
not enabled... and you guessed it, those enables are CPU-controlled, so no program running means almost all of the board is inactive. I was
basically getting ready to give up. It's a good thing the board came in a black box because they wear black at funerals and this was going
to be its permanent coffin lol!
The next day I went back and had a look at it again. Having just fixed a bunch of Sega System 32 boards with bad V-Series CPUs and having 3 spare V30 CPUs in my parts bin I just decided to swap out the V30. Powered on and....
It's working LOL!!! So yeah, just a bad V30. Not surprising after the System 32 repairs so it just looks like NEC V-Series CPUs are junk. If
you have a dead Irem board that shows only a white screen with random blocks suspect the V30! Incidentally, that RAM on the ROM board
will kill the board if bad but part of the start-up test does happen and some random graphic movements appear on screen which then repeats.
So if you only see a partial start-up test then it repeats, the top board RAM could be the issue. But if you only see a static white screen that top
board RAM is not the main issue.
Another thing, the V30 is supposed to be 8086-compatible so I plugged in an i8086 to see what would happen. These Irem boards do not work with a
i8086 so don't bother trying as they are obviously using some V30-specific stuff that isn't part of the i8086-specification.
16th September 2024
I've been having too much fun repairing a whole bunch of Sega System 32 Multi boards (so far 2 out of 6 are working, logs coming soon). I
had to physically drag myself away from that to write up this log before I end up with too much stuff to remember hehe!
So, getting back to the Alien 3 The Gun repair....
The board is dead. I removed the ROM board and noticed this chip....
This is the 315-5387 tile generator custom chip (shown on the schematics on the 'scroll' page). The sticker is slightly brown and when
powered on this chip is burning hot... obviously blown up. I pulled the chip and replaced it with another taken off a junk board. I also
noticed the 8 nearby zip RAMs are very hot so I removed all of them (more on this later).
Of course, powered on, the board is still dead.
This lower section of the board is very important....
The MB3771 chips provide the master reset output on pin 8. The 74F112 do the clock dividing and the 74ACT244 buffer those clocks to chips all
over the board so everything in this section must be 100% working. I checked pin 8 on the reset chips at power-on using a logic probe and the
output starts low and goes high so the reset chips are working correctly. I measured the clocks at the oscillators and the correct
frequencies are present. The clock goes into the F112 chip and the clock outputs are missing so I pulled and tested it....
IC23.... dead.
I replaced the chip and the outputs are now present on IC23. The clocks go into the 74ACT244 at IC24, inputs are present, outputs are missing so I pulled and tested it....
IC24.... dead.
I replaced the chip and the outputs are now present on IC24. The 3 chips to the right do basically the same thing and also had no outputs so
I pulled and tested all 3 chips....
IC39.... dead
IC52.... dead
IC53.... dead
These chips were replaced. Now with the clock section working there is some activity on several chips across the board. Probing the main program ROMs while powering on
shows there's no attempt to access them. Here's the relevant CPU section page from the schematics....
Previously System 32 schematics were available but page 1 (CPU) was missing. I suppose we should be thankful this became available recently
but it's a bit sad that in 2024 with everything that has been publicised over the last 30 years that people STILL don't know how to scan
rare documents. 1-bit black/white is no good!!! These old documents are not in pristine condition and have lighter and darker areas. 1-bit
black/white means either a pixel is black or white, there is no lighter area. If something falls outside the threshold it becomes black or
white, either blackening detail to become a black blob mess or wiping it out entirely to white. Of course this scan is exactly like all the
other previous scans with unreadable areas. It's important that all text and signal names are fully readable otherwise the scan is almost
useless. Next time please, at the very minimum, SCAN DOCUMENTS IN GREYSCALE at 600DPI!!!!! We don't give a crap how
big these files are now, this isn't 1994 with a 9600 modem!!! If the original document is still available it should be re-scanned in greyscale
at 600DPI and uploaded to archive.org so it is *correctly* preserved for future use. /RANT
So this page shows V60 CPU (PGA version), custom Sega 315-5385 Bus Arbitrator / Memory Controller, 5 logic chips, 1 GAL and a bunch of
inputs and outputs, a lot of them coming from or going to page 9 of 9. Page 9 is the ROM board connector page so any signal on page 9 is
essentially the ROM board / ROMs.
This page from a non-public V60 manual is also required due to the poor CPU page scan....
The V60 clock is on pin F11 and reset is on pin B2. Probing those pins shows they are present. Incidentally, the resets are buffered from
the MB3771 through a 74F240 at IC13 which has two reset outputs. One goes directly to the V60 and one goes somewhere else (more on that later ;-)
The next thing to check is the main program RAM at IC36 and IC37. Those checked out good on my chip tester.
I swapped the GAL from my working board, no change.
The main program gets pulled into the CPU through 2x 74F245 bi-directional bus transceivers at IC49 and IC50 and custom Sega chip 315-5385
controls most of it. I injected a signal into the F245's and the outputs respond so they appear to be working. There's no easy way to
diagnose which part is not working, we have to go with the 'suck it and see' method.... basically change stuff and see what happens.
I pulled and replaced 315-5385....
No change, board is still dead.
BTW, pay special attention to this chip and how it is configured. On the 837-7428 and the rev -01 boards there is a little solder blob on
the chip between pins 58 and 59 and a nearby trace is cut. This is a factory Sega fix due to a routing screw-up in production. If the board
has this solder blob and trace cut the solder blob must be put back after the chip is changed otherwise the board will be dead. Yes that's
right... I tested it on my working board, removing that solder blob will cause the board to not boot.
Getting back to that 'other' reset signal, it goes to the custom I/O chip. Incidentally this same reset goes to lots of other chips,
including the tile chip I previously replaced. A missing reset on the tile chip would cause the board to appear dead. Anyway, I know from
previous repairs and experiments that if the I/O chip is bad (or missing) the board will not boot. Pin 64 is a reset output which was only
low at power-on. But of course this chip will not output a reset unless the CPU is running as the CPU tells this chip to output that reset
signal. However the I/O chip connects to the main address and data bus so if this chip is faulty it can bring down the whole system. So I
swapped out the 315-5296 custom chip....
No change, board is still dead! However, probing the ROMs at power-on now shows a tiny pulse as soon as power is applied. This is progress
and means the I/O chip was bad. At this stage there's nothing remaining unchecked except the CPU. The problem is I don't have another spare
V60 CPU in PGA68 package. I have a couple of non-working System 32 boards but they use the QFP120 V60 version with part number
uPD70615. These are also used on Sega Model 1 and I have a couple of junk boards laying around somewhere so I have at least 2 more spare
QFP120 V60 CPUs there too. The interesting thing is the System 32 main boards rev -02 and -03 can actually use PGA68 or QFP120
version chips! Something to remember... (and more on that later hehe!)
My working System 32 board just happens to use the same PGA68 V60 CPU but it's not exactly spare. I had a look on the usual online places
and no one is selling a PGA68 V60 CPU. My only option to know if this is bad is to pull my good CPU and swap it over. But I really really
don't want to have to desolder it twice (plus desoldering PGA chips is *really* annoying) and I don't have a PGA68 socket.... or maybe I do
hehe! In the past I've made some PCB projects for Amiga computers and built a PGA socket for a 68030 Accelerator board from female header
pins. So that's what I did. I first removed the working CPU, built a socket on my working board and plugged the working CPU back in.
Everything still works :-)
I removed the V60 on the non-working board and plugged it into my working board.... my working board is now DEAD!! So this can only mean one
thing....
R.I.P one incredibly rare and difficult to find V60 CPU lol!
Ok so I built a PGA68 socket on the non-working board, plugged in my CPU, powered on and got this....
Well it's no longer showing just a black screen, there are some colored bars showing! Of course all the tile and sprite RAM is missing so
it's not going to show anything hehe! I probed the I/O chip pin 64 and it's high so the reset output is working. This reset goes to the Z80
reset pin and the Z80 is also active! The main program ROMs and program RAM are also active! It's probably working... I need to put some
VRAM on there hehe! My chip tester has support for these weird HM53461 Dual-Port VRAMs (added at my request with testing by me) but only in
the DIP package. These same dual-port RAMs are used on several games from this era including Mortal Kombat (DIP package) and CPS1 main
boards (ZIP package) so I have plenty of spare chips, but no way to test them. It took a while to build it but I wired up a rough DIP to ZIP
adapter. I was initially going to use a piece of vero board but ZIPs have two rows of pins that are offset by 0.050". I looked around and
found a junker board that had zip RAMs on it so I *ruthlessly* chopped off that section of the board and wired up a rough prototype DIP to
ZIF adapter. I tested all those VRAMs I removed and found 2 bad chips....
I can't trust any of that hot RAM I removed so I just replaced all of it with RAMs taken off a different board and tested in my chip tester....
I powered on and got this....
HOLY CRAP!!!!!!!!!!!!!! It's working!!!!!!
The game is fully playable and sound is working too. The only issue seems to be a very minor graphic glitch at the bottom. It's supposed to
show the credits but it shows only garbage.....
Fortunately on System 32 the test screen has a pretty useful memory test that tests all the RAMs except the two connected to the sound chip.
I ran the memory test....
Ok so IC68 and IC69 are bad.... but I just replaced them :-/
I pulled them again and replaced with two more RAMs and the error still shows. Let's have a look at the schematic....
IC68 and IC69 are part of the 'scroll' RAM. They connect to custom chip 315-5387 (the same chip I replaced earlier).
IC69 has DQ8-11, SD8-11 and IC68 has DQ12-15, SD12-15. I did a continuity trace on all those pins and they are joined to the custom chip. I
also traced all the other pins (address, ras, cas, oe etc) and they are all joined to the custom chip. Note the address pins go through
75-ohm resistors so these have to be checked from RAM to the resistor, then the other side of the resistor to the custom chip. Since the
game is 99.99% good I assume the custom chip is ok. Also connected to the RAMs and custom chip are 2x 74LS244 at IC55 and IC57 and 2x 74F374
at IC54 and IC56. The chips that connect to DQ8-11 and SD8-11 are IC54 and IC55. I pulled IC55 but it tested good. I pulled and tested IC54
and it failed... all the outputs are dead. I replaced the chip, re-ran the memory test and everything passes. I ran the game and the graphic
issue is fixed so that's the end of this repair.
However that's not the end of this log... yet ;-)
As part of the repair I need a PGA V60 CPU. I'm not giving the board owner my PGA V60, no no no. That newer rev board gave me an idea. The V60 PGA
and V60 QFP both fit in the same area. I'm wondering.... how hard would it be to make an adapter that plugs into the PGA holes and on top
has a QFP120 V60 chip. It turns out to be not very hard at all....
This is my prototype adapter. Basically the later rev System 32 main board has all the routing (PGA<>QFP) so I just copied it and verified
the pinout is correct as per the V60 documents and another cross-reference document that I got from a very special emulation dev. The System
32 board has 4 layers but I made the adapter only 2 layers to save costs so I had to do some creative routing for the VCC and GND traces.
This will be put into the next batch of PCBs I get produced and then I will test it and report back here.
Anyway, that's the end of this log. But don't worry there's plenty more coming. I've already revived TWO totally dead System 32 Multi boards
(and I'm working on another two right now) and will have logs on those soon :-)
5th September 2024
Wow! When it rains it pours! A bunch more repairs just arrived and it's *actually* raining outside hehe!
Sega System 16A Wonderboy III Monster Lair
The game is working. The first pic shows a bonus item that can be collected to give a power-up. On this board when that *exact* power-up is
collected the board resets back to the title screen!! The natural solution is to remove the silly epoxy block and replace with a 68000 +
decrypted ROMs. That was done and the game now plays fine and when that bonus item is collected the game continues working normally. The
board went back to the owner quickly before I was able to get any proper pics but it's basically just drop in a 68000 and change 2 ROMs. The
pic shows the board back in the cabinet after the repair was done.
Raiden Fighters Jet, Seibu SPI hardware
The red arrow in the pic above points to a PAL16L8 marked 'MCTL01' which is dead and has killed the board permanently. Unfortunately no one
had the foresight to dump the PALs on Seibu SPI hardware so there's no backup. That's a shame as it's just a PAL16L8 and easy to copy (at
least for me with my PAL cracker) but I don't have access to any SPI boards. I asked a few local friends if anyone had a Seibu SPI
motherboard they could loan me for 10 minutes to copy a PAL. Someone had a Raiden Fighters 2. I checked the board and it's running on the
later and smaller cost-reduced V2.1 hardware and doesn't have that PAL. THE. END. GAME. OVER.
Let this be a lessen to everyone who owns original hardware, make
some effort to get the PALs backed up because when they die it's game over if there's no backup available. Apparently the guy paid something
like $1200 for the board LOL! Maybe now he'll start thinking and see that a Raspberry Pi4 or a $50 Android TV box can emulate any simple
joystick/button game perfectly without any board faults hehe! The Pi can even be programmed to output 15K video so it can basically be
plugged directly into any old cabinet. Oh well, another one for the junk pile hehe!
Sega System 16A Shinobi
Yup! The same one is back again hehe!
The board is working but the music is noticeably distorted when the volume is turned up. The owner had previously changed the caps in the
sound section and both TL084 opamps. The digital sound samples coming from the D7751 seem to be ok and the YM2151 is playing music. The
digital output from the YM2151 goes into a YM3012 Digital-to-Analog Converter so this is the obvious place to start.....
I pulled and replaced it (also adding a socket), powered on and that seems to have fixed the music.
I later swapped that bad chip onto my Konami Top Gunner board and it also had distorted music so the YM3012 was definitely the problem.
When working on the bottom I also noticed this....
It's amazing this didn't cause a non-booting game as it's very close to the CPU section. Ummm, yeah, when working on boards be careful about
solder splashes.... not a good idea to haphazardly splodge solder all over the back of the board lol!
1st September 2024
A box of boards came in for repair. I'll detail a few here and the rest will be looked at later.
P-47 The Freedom Fighter, Jaleco, 1988
The game works but there's no sound. This game uses a 68000 CPU for the main program and another 68000 CPU for the sound. The 2nd 68000 was
not active on any address or data pins. I first checked clock and reset and they were present. I read all the ROMs and some turned out to be
unknown. It turned out that this version is not in MAME so it was added and the game worked fine so the ROMs must be ok. I piggybacked one
of the RAMs next to the 68000, powered on and the sound worked fine. So this was just a simple RAM fault.
Sega System 32 Alien 3 The Gun, Sega, 1993
I was told by the owner that the power supply blew up and when it was replaced the board wasn't working anymore.
I tested the board and yes it's really really dead... no clocks, no reset, no activity anywhere. If you are going to try to fix a blown-up
System 32 board you absolutely must have another working main board to narrow down the fault. You must also have advanced repair skills, a
crap-load of spare parts and many years of experience to bring this type of dead/fried board back to life. These boards are very tricky to
fix due to all the custom chips so I will start with the ROM board first. I plugged it into my working System 32 main board and got
this....
Wow, well it sort of works hehe!
I read all the ROMs and they checked out ok against MAME archives.
Sound is also working which means the sound ROMs and protection GAL are also ok. On these System 32 ROM boards the GAL controls the
output-enable (OE) pin on the sound ROMs so if sound is working you know the GAL is ok.
So ignoring all the stuff that's good only leaves a bunch of logic. The larger 42 pin mask ROMs are for the graphics and they are buffered
via a bunch of 74F245 logic chips....
I haven't touched these, they were already in sockets. Looking at the bottom shows all the chips have previously been replaced. Hmmmm....
someone who worked on this previously seems to know something...
I pulled the chips in sockets (there were actually 3, one is out of frame) and they all tested bad! Two chips with same fault, all outputs stuck
high, the other with one output stuck high....
I replaced the 3 socketed chips and it improved the image dramatically but it didn't fully solve the problem. I noticed the 74F245 chips ran
hot so that might have been why they failed. At this stage I'm not playing games with these chips so I pulled all the remaining chips (5)
and 3 tested bad. They can't be trusted and because they run hot I replaced all of them (including fitting sockets as they will probably
fail again) and that fixed the ROM board :-D
That's enough for now. Come back later and I'll have the main board repair in the next log which actually took about 2 weeks to fix, meaning
it's going to take some hours to write it up.
I'll leave you with a quick preview of one of the very rare and unusual boards that was also in the box that arrived, which I dumped and it was added to
MAME recently thanks to quick work by Osso. While the title screen says Taito, this board isn't actually a Taito board. But more on that one
later....
23rd August 2024
I just ran trojans on the HOST / link boards (#10 and #11 in the list posted earlier) and everything looks fine so everything has been
trojaned and this task is complete. These may or may not be working in MAME at some point in the future. The HOST board and the Mahjong
board versions and games must match otherwise the mahjong board only shows 'WAIT LINK' and never connects. After wiring them up one of them
links and runs. I'm not sure but it looks like only Man Guan has a matching pair and the title is actually Man Guan Cai Shen 2. The other
game Cai Jin Shen Long won't connect and therefore only shows 'WAIT LINK'.
I put up a quick and dirty video of the HOST board connecting and showing the 7-segment LED display then some video of the game attract
mode. Watch closely as the display shows LK and scans each ID for an active connection.... the last one (20) is different :-)
UPDATE 28th August 2024: I got Cai Jin Shen Long linking and booting so I added a video of it above.
22nd August 2024
I just ran a couple more trojans for Long Teng Hu Yue and Zhong Guo Chu Da D and here's the preliminary result, this time thanks to quick
work by Haze who has taken on the task of hooking up all these IGS027A games....
Zhong Guo Chu Da D, IGS, 2000
Long Teng Hu Yue is working but only shows 'WAIT LINK'. The DIP switches are not hooked up yet. On real hardware, with DIPSW2 #4 ON, the
game ignores the link check and boots up. Also FYI, DIPSW2 #1 ON gives demo sound.
21st August 2024
Here's another mahjong update thanks to quick work by Osso....
Te Yi Gong Neng. This is the joystick version of Long Hu Bang II.
Te Yi Gong Neng means Supernatural Ability (you can randomly get any tiles you want in the game).
UPDATE 22nd August 2024: Pics above changed to latest (better) version after some fixes by Osso.
I also received some more trojans to run on PCBs so I trojan-dumped the IGS027A chip for these games....
Shuang Long Qiang Zhu 3 (slqz3)
Long Hu Da Man Guan (lhdmg)
Long Hu Da Man Guan Plus (lhdmgp)
For those who are curious how many more can be done, I went through all the boards with 027A chip here in my PCB racks and there are only 4
more to be trojaned...
Long Teng Hu Yue (lthy)
Zhong Guo Chu Da D (zhongguo)
and the two HOST boards that arrived a few days ago.
Any other games in MAME without an 027A dump will need a working PCB to be acquired and dumped, otherwise those games will remain
non-working. Here's the source code if you want to
check it out.
19th August 2024
For all of you mahjong fans out there here's some mahjong news.
This was just hooked up thanks to quick work by Osso....
Man Guan Cai Shen, IGS 1998
In other B-I-G news, a new method has been found to dump the internal ROM of the IGS027A chip! As far as Mahjong emulation goes this is
about as pant-creaming as it gets hehe!
Thanks to some trojans that were written yesterday by one of the devs I have just completed trojan-dumping the internal ROMs for the
following games....
Fruit Paradise (fruitpar)
Man Guan Zhi Zun V100CN (mgzz)
Man Guan Caishen 3 V101CN (mgcs3)
and one working now thanks to quick work by Haze (who has taken on the task of getting these 027A games hooked up)....
Que Long Gao Shou (qlgs)
I'm sure many more will follow soon.
Here's a sneak peek of the process....
Here's a snapshot of the dump....
14th August 2024
A batch of undumped Mahjong boards just arrived, thanks to Dyq and little0.
These are very simple boards as far as dumping goes so they will all be dumped in about 1 day total. Get ready for the mahjong onslaught! :-)
I'll add an update here later with the game names so check back later.
UPDATE:
Here's the list of games. Refer to the pic above for the numbers.
1. Long Hu Da Man Guan (IGS 1999)
2. Long Hu Da Man Guan Plus (IGS 1999)
3. Long Teng Hu Yue (IGS 1999)
4. Man Guan Cai Shen (IGS 1998)
5. An older version of Shuang Long Qiang Zhu 2 VS (IGS 1998)
6. Te Yi Gong Neng (IGS 1996)(Joystick version of LHB2)
7. Jin Hu Lu 2 (IGS 1999? 2000?)(Poker game)
8. Man Guan Cai Shen Link Version, Slave Extension (IGS 1999)
9. Cai Jin Shen Long Link Version, Slave Extension (IGS 1999)
10. Cai Jin Shen Long, Master Host (IGS 1999)
11. Man Guan Cai Shen, Master Host (IGS 1999)
As far as emulation of these, several have IGS027A chips so emulation is not possible unless the internal ROMs are dumped. Several have bad NICAD battery damage resulting in
one board having a bad program ROM. The end result is likely only 4, 6 and 7 can be emulated successfully. If any are working in MAME, screen shots
will be posted here :-)
28th July 2024
Over the last few weeks I've been repairing a batch of 23 Daytona sound boards for a local friend...
The 5 boards at the back on the right side were scrapped for parts as they were rotten all over the board.
The 6 boards at the back on the left side are slightly less rotten and were repaired but will not be going back into service due to them
being unreliable, where it's highly likely one of the other rotten areas will become more rotten over time and kill it again. This has
already happened once and some of these were returned as DOA from my last repair batch.
The 9 boards at the front are in good condition, are fully working now and will go back into service. There were 2 more that were also
repaired but they have already been taken as my friend needed a couple of working boards quickly.
One of the scrapped boards was so bad that even the bottom side was rotten. Just for fun I decided to fix it....
Heheh!! This took 2 days to fix. I will clean up the wire patches later. It turned out to have over 25 broken/rotten traces/bad vias. This
particular board has random damage around the ROMs and CPU but the damage can be randomly located anywhere, sometimes isolated to
one place or spread all over the entire board. The custom Sega chip was covered in what looked like coke and was blown. It was so bad the
coke corroded traces under the chip which I rebuilt before replacing the chip with another one. The sockets were so rusted and corroded that
none of the pins on any socketed chips were making continuity with the main board hehe! This board works perfect now but will also not be
going back into service.
You may be wondering how these got in such bad condition. This is **extremely** common. Here's a couple of pics of the sound board installed in
some random clueless loser's Daytona cab that I captured from a youtube video....
Of course they were trying to fix it, wondering why it didn't work without using one of their brain cells to actually look at all the crap
all over the board and think, well maybe I need to clean up this mess and keep it clean so this doesn't randomly die. Nope! It just gets
ignored, randomly dies, sent out for repair then slapped into the cab and run again until it drops lol!
Anyway, this isn't what this post is about. As I was going through the boards there were a lot of the ROMs missing as they were taken at the
time other boards came in and were exchanged by my friend on other boards with rotting ROMs with legs so rusted that they either just fell off or were torn off when the
bad ROMs were extracted from the rotting rusted sockets lol!
However there were a few EPROMs remaining including these ones....
These are the sound program ROMs for *something*. The labels are basically unreadable but using magnification I was able to see 489 and 490.
I read them and expected them to come up as one of the Sega Model 1 or Model 2 games (this sound board is used on Model 1 and the early
Model 2 games). But no... they were unknown!! I first thought they were bad but the actual ROMs are in good condition and read fine without
any errors. After checking through the MAME source I realised that 489 and 490 are the previous numbers in this sequence..... 16491, 16492,
16493 and 16494. These are of course the 16Mbit mask ROMs used on the Daytona sound board. So the unknown EPROMs must be 16489 and 16490.
Hmmm. so I wonder if they work... I plugged them into one of my working boards and it appeared to work normally just like any other Daytona
sound board, playing the Daytona USA theme song. I coined up and noticed it wasn't as 'bright' sounding. I went into the test mode and
played all the sounds and some of them didn't play, but did play when using the standard 16720/16721 EPROMs. It turned out that these EPROMs
are from the very first Daytona USA Deluxe cab and that version doesn't have the extra sounds in the sound test screen. This was a very
lucky and rare find. They could have very easily been removed and tossed in the bin by the previous person who had these or erased and
re-used. It was probably only because the labels were damaged that they couldn't be easily identified as Daytona ROMs so they were just left
there and the board tossed on a pile of crap that eventually found its way to me. A very lucky find indeed... 31 years after the release date! :-)
Anyway, it's been added to MAME as part of the 'daytona93' ROM set and you can listen to the differences by playing that version.
18th June 2024
A Namco System 10 Mr Driller 2 came to me as a free junk board a while back (a few months ago) and this is a log of that repair which
actually took 3 months to fix believe it or not lol! Well there was a lot of thinking and sleeping and other jobs going on in that period
and a lot of non-productive time but now the complete repair log can finally be written up.
The board is completely dead and shows nothing on screen. Over the years I've repaired a few of these boards and some others very similar.
The specific DRAM used on these boards for the main CPU RAM seems to go bad for no reason so I swapped that out for some new RAMs, powered
on and this showed on screen....
Well it's no longer dead but still not working :-/
All that junk on the screen is flashing and moving around wildly, although the game appears to be running. There's also really bad
screeching noises coming from the speaker so the sound has issues too. The video section of this board comprises several parts. There's the
main Sony graphics chip, 2 connected SDRAMS, a 24 bit video DAC and a video pre-amp driver chip. I'm guessing one of these chips is suspect
but there's no way to test any of them easily so they have to be swapped with another known working chip. The order of changing them just
happens to be the reverse order that I listed them in (hehe!) due to each one requiring more work to swap it. The first chip to swap over is
the "Sony CXA2067AS Preamplifier For High Resolution Display" chip...
Changing that didn't fix it and the issue is exactly the same.
The next chip to swap is "Sony CXD1178Q 8-bit RGB 3-channel D/A Converter" chip....
Changing that didn't help either and the issue is exactly the same. In the past I've found some boards with a color missing and this chip
was the cause of it. However in this case the colors are fine.
The next parts to swap out are the two SDRAMs. To make it easier I took some SDRAMs from another working board as these are easy to swap over with new replacement SDRAMs bought later...
This is getting annoying.... changing that didn't do anything and the issue is exactly the same! That only leaves the large QFP chip....
Sony CXD8561CQ. I could take it from a working System 10 board but it doesn't make sense to scrap a working board to fix another identical
board that may or may not be repairable. I looked through a bunch of junk boards and I didn't have exactly the same chip but I did find a
CXD8561Q on a junk/dead ZN1 main board. Could it be the same? Only one way to find out so I swapped it over, powered on and it's totally
screwed up now, like the sync is missing lol! I then realised what was wrong....
OOPS! Ummm, yeah I must have knocked off those two small parts, a resistor and a capacitor. The resistor is connected to pin 156 and
according to info on the net it's composite sync. Yeah that will screw up everything if that signal is missing hehe! No idea where they
went though, they just *disappeared* hehe! I got a new resistor from my SMD resistor stock (22 ohm, size 0603) and put back the resistor and
powered on....
Wow! That has *almost* fixed the problem!! But it kind of looks like the chip isn't compatible as some screen sections are good and others
are completely wrong/missing data. Weird! Looks like I have to remove it and find the exact same chip. After some hours (actually some days
later) I finally found another board with the same chip on a Konami System 573 main board. This was originally from a Dancing Maniax and is
the fairly common GX700 main board. So I swapped the chip over and nothing changed vs the original chip! WFT??!! Now I'm thinking maybe some
of the legs were not soldered correctly so I checked everything twice and everything was perfect, actually better than factory... Namco
boards are known to have poor QFP soldering due to the way they were reflowed at the factory and it's a common issue to see these Sony chips
come loose, especially on Namco System 11 and System 12 top CPU boards. But not here, this is "Guru-Soldered(c)(tm)(r)" and is perfect hehe!
So what could be wrong? I was going to start desoldering and testing all the LCX244 and LCX245 logic chips but instead looked over the
bottom of the board. There are a lot of very, very, very tiny vias (0.3mm diameter) under the RAMs and Sony video chip. These vias are
extremely close together, perhaps even too close. I went over the board with a magnifier and noticed this....
Are you joking? Could that be it? A short between two vias???? Holy crap! I scraped away the solder joining those two vias together and then powered
on....
OMG! It's fixed!!!!! LOL!! My guess is the owner was running the game and when it failed they tossed it onto a pile of crap and it got
kicked around for some time before eventually finding its way to me. During that period it must have rubbed against something and the solder
on those vias was joined together by brute force hehe! Ok so the video fault is fixed and highly likely the original Sony video chip is
ok so I'll put that back onto the Konami board later. Now I'm REALLY curious what those two vias are connected to so I traced them and
found they are tied to the SDRAMs on pins 29 and 30. The RAMs are tied together so effectively both SDRAMs pins 29 and 30 were shorted
together. The specific chip used on these boards doesn't seem to have a datasheet available (Oki 54V25632). But under the chip is a
number... PD481850. I looked that up and it's a NEC uPD481850 128kB x32-bit x2-banks SDRAM. The datasheet pinout doesn't match what I'm
seeing on the board....
Pin 29 is "A9(BA)" (bank address) and pin 30 is no-connect! Eh?? That can't be right. Now it makes sense why when using the other Sony chip
the image got slightly better. Pin 30 on the RAM likely goes to an internally unconnected pin on the CXD8561Q chip. At least it looks that
way. These chips were used in the PU-8 Playstation mainboard in model SCPH-1001 and unfortunately that schematic was not leaked so there's
no reference pinout for it. But it would explain why the image was almost ok since pin 29 on the RAM was not actually shorted to anything
since pin 30 is a no-connect on the video chip and the reason why it wasn't fully fixed is because the CXD8561Q supports less RAM. Or
something like that. Pin 30 on the RAM is tied to the video chip on pin 121. I checked the ZN1 board where I took the CXD8561Q chip from and
pin 121 is tied to a trace then to a resistor but the resistor is not fitted. So a ZN1 board can probably use the 256kB chips too but the
board is configured to use the 128kB chips. The PSone schematic shows pin 121 on the CXD8561CQ video chip is no-connect. After some research
I found the pinout of the Oki chips using a cross-reference. It's the same as ISSI IS42G32256. The pinout (checking pins 29 and 30) confirms
Oki 54V25632 = ISSI IS42G32256 = Samsung K4G163222 which is used on the PSone PM-41 main board. These RAMs all have pin 30 as A8. For some
reason Namco may have planned to use the NEC uPD481850 128kB x32-bit x2-banks RAMs but maybe they were not available in large quantities so
decided to use instead the newer and larger 256kB x32-bit x2-banks SDRAMs with the newer CXD8561CQ chips. Some info on a PSX site suggests
the later video chips were in production at that time and since they supported more RAM were used with larger SDRAMs but on the PSone pin 30
was grounded and the schematics show CXD8561CQ has pin 121 not connected so only giving the PSone 1MB VRAM. That shows that the PSone and
the other Playstation models were more capable but purposely cut down to make them not as good as their arcade counterparts hehe! I checked the
System 10 board and pin 30 is not grounded so that means the System 10 board has twice as much VRAM as the PSone which actually follows with
the earlier System 11 and System 12 which also had more RAM than the console equivalents. It also means if the VRAMs fail you can't swap
them with the type written on the board since uPD481850 is only 128kB x32-bit x2-banks with pin 30 not connected internally and the Sony
CXD8561CQ requires the 256kB chips. Anyway, it's time to move on.
The sound is still nasty. I played a game and the sound seems to be in time with the actual soundtrack but
is just noise. I looked at the output audio section near the main amp and someone has been playing around there....
Ummm, no wonder it sounds bad, those are LM358 op-amps and the board should have JRC3414 op-amps. Those are specifically designed for audio
whereas the LM358 chips, even though they have the same pinout, are general-purpose op-amps and are not compatible with the JRC chips. I swapped
them over to proper JRC3414 chips taken off a junk Namco System 23 board....
Powered on and.... errr... it's not fixed!!!! AARRGGHHH!!!! LOL!!
Well it sounds a little bit better, less distortion but still noise coming out. A bit of research is required now. This System 10 board is
essentially a late model slim/small PSX known as the PSone. It uses the same model Sony chips. Fortunately schematics are available. The
sound chip is Sony CXD2938Q. This is a combo DVDROM and sound chip. Let's have a look at the schematic, specifically the audio section and
see if there are any interesting signals shown....
Yes!! There are two audio out signals named AOUTL (pin 147) and AOUTR (pin 150) which are the analog audio outputs, great!! I highlighted the signals in red. They go from the audio chip to the op-amp then directly out to the output cable. On the PCB I traced those pins and they go to a couple of vias near a SMD capacitor then directly to the JRC op amp inputs....
I probed those pins with my logic probe and I can see activity in time with the game sound but it sounds the same on the probe piezo
speaker, just noise. That same noise is also on the op-amps but they are further down the line and were changed so they are good. I don't
see anything else sound related on the board other than the Sony sound chip. Except a RAM.... IS41LV16256. It's a 256kB x16-bit EDO DRAM.
Checking some PSX sites shows this particular sound chip has external RAM so that must be it. Either the Sony chip is bad or this RAM is
bad. Of course it's easier to change the RAM and these RAMs are common and easy to buy replacements so I pulled another RAM off a working
System 10 board and swapped it over.
I powered on and that fixed the sound!! Yay!!! Job done, time to go back to sleep ;-)
p.s. Another thing I just discovered... The board I took the CXA2067AS chip from (some months ago) was still missing the chip and I will
have to order a replacement later. I just found that same board and plugged it in to test it but without the chip since I did not have one
yet. I was expecting to at least hear the game audio. I was really surprised to hear nothing! No game sounds at all!! There's no activity on
the board and the game is not running. This suggests that the CXA2067AS chip is monitored by the program and if there's no feedback from it
then the board switches off or the program just halts itself. Perhaps to protect a monitor from a faulty video circuit or for other
nefarious reasons, we'll never know. Anyway, note to self, if you remove a CXA2067AS chip and months or years later discover that board
laying around, test it and find it's dead... well it's actually NOT dead, so put the chip back on and it should work fine if it was working
before removing that chip! Hehe!
Note to self #2:
Remember this....
Ah yeah, I took those little 10K resistor pullup packs off another System 10 board to fix something about a year ago but didn't put them
back lol! That's explains why it's dead now because they connect to the main data bus on the CPU and pullup pins SD0-SD15. I still don't
have any to replace them but I found some 4.7K pullups on a junk Namco System 23 board so I put them on and tested it and it works fine so
either value can be used :-)
Update: Oh I was looking through the pics and found that disappearing resistor and capacitor!!
They were hiding next to the electrolytic cap, resistor is upside down and the cap is next to it. I just checked now and it's gone again,
most likely they got flicked away into the 'SMD Black Hole' (where all lost tiny SMD parts go) when I cleaned up the board with IPA
hehe!
12th June 2024
Here's an update on Pacman Battle Royale emulation... player 1 controls are working so it's playable now :-D
5th June 2024
If you have been following MAME additions closely you will have seen that the IBM 5100 and 5110 were added a few months ago. This is said to
be one of the first portable computers and was released in 1975 and is a historical stepping stone that eventually brought about the 5150.
The 5110 was largely targeted at businesses needing to do any kind of complex calculations and the language provided is heavily
maths-orientated. The model that is emulated is the top-of-the-line BASIC+APL 64K version. It's a bit difficult to use due to the
non-standard keyboard but even for simple typing the manual is definitely required to know how to get some of the special symbols to show on
screen. For example there's no exclamation point on the keyboard. To get that you have to press shifted K to show a quote mark ' then you
cursor left and type over the top with a period . and it magically turns into a ! lol! Oh, I mean "lol shifted K cursor left period". This
is one example but there are dozens of special symbols in the character map that are not on the keyboard. It's actually pretty amazing it
works at all given it's using the very bizarre IBM PALM CPU which uses technology reminiscent of the Apollo 11 Landing Computer....
basically a lot of little sealed tin-can modules spread across multiple PCBs.
So why am I bringing this up now? I've been working on some artwork so it can be more useable. The first pic
is a snapshot from within MAME. The overlay provided here is BASIC + APL + COMMs. I can imagine something that high-end in 1975 likely cost
as much as a house back then. When viewed full size it looks great! The second pic shows real life... unfortunately the emulated screen
is almost unreadable on my 27" LCD monitor due to the font being made from dots so it looks a bit like the output from a 9-pin dot matrix
printer. The resolution is 640 x 384 but with a tiny 5" CRT that makes for very difficult reading so you may have to run this on a 60" 4K TV
to be able to read it heh! There's also a switch on the front panel to reverse the screen text so the screen is white and the text is black.
That's probably more readable but I don't really want my eyeballs burned out by a bright white screen. My source image is 600 DPI and
over 5000 pixels wide so there won't be any problem viewing it at larger sizes. Also unfortunately, there's no load or save yet so don't
go trying to write any large programs to solve world hunger or interplanetary space exploration. Although I tried a save-state and it does
restore a program in memory so that's one way around it for now. Finding commercial software for this could also be difficult and I'm really
curious to see what this computer was actually used for and if any commercial software was archived. For now it's possible to type
something and get it to run BASIC and APL programs. These are early work-in-progress pics... the final artwork is still some weeks away from
being done as I'm still referencing manuals and pics online to make it more accurate. The last pic shows the real thing for comparison.
My artwork is pretty close :-)
Here's another example of the serious computing power this thing has ;-)
If you want to play along click here to get the MAME save-state for this program. Put this into
MAME\STA\IBM5110\ Run MAME ibm5110. Press SCROLL-LOCK to enable the local PC keyboard, press F7 and select 1 to load the save state.
Press SCROLL-LOCK to re-enable the emulated keyboard. For some reason the emulation gets confused by having the program shoved into memory
and starts running but not from the beginning (save states are not officially supported in this driver). Press DEL to stop the program. Type
RUN and press enter to run the program. Total run time is around 75 seconds.... approximately 2.5 times slower than a Commodore
64 ;-) Although it does have around 60kB free so twice as much memory available for BASIC. It has some other nice things about it.
To edit a line just cursor up/down/left/right then type over it and press enter... a lot like the C64. The BASIC is a bit erm...
'lacking'. Only one statement per line, no WHILE, no ELSE, IF-THEN must only point to a GOTO and line number. Lack of program flow control commands means lots of GOTO and spaghetti code. So for example "IF T=1
THEN F=0: M=I" or "IF T>1 AND F=1 THEN M=M+1" won't work. Also no boolean logic, although that kind of thing can be done using APL if you
are crazy enough to try. I suspect most commercial programs were written in APL since that seems to be more powerful and flexible, and will also confuse anyone looking at it which is a kind of software-protection ;-) Be REALLY careful when you make a mistake because on an error there's a high-pitched beep that will cause
you to crap your pants lol! What can I do next? Manage my budget... ummm no need for that I retired at 47, compare the cost of fuel
locally vs driving to other stations with cheaper fuel... umm no, I am retired so I rarely drive now and my sports car just sits in the
garage, oh I know... something really important... calculate how long it will take to erase an EPROM using only sunlight! There's days of
fun here and that's probably how long it will take to provide the answer hehe!
4th June 2024
PAC IS BACK!
Here's an update on Pacman Battle Royale... except for no controls it's now booting and runs in the Play! emulator....
This game uses an extra I/O board called "A.I. PCB" that provides the joystick directions for all 4 players. That board is totally unknown
as I don't have it and there are no pics of it on the net so it will take some time to figure it out. The start-up A.I. PCB checks have been
bypassed but the board is not emulated so there are no controls. For now you can get the latest version of Play! and watch the attract mode.
At least you can when the latest changes hit github. If coin and start are also hooked up (which comes from the standard S147 I/O board) it
might even be possible to coin up and start the game (obviously there will still be no controls ;-) Keep an eye out as it shouldn't be
too long before it's released :-)
11th May 2024
About 2 months ago I dumped Pacman's Arcade Party. It's now working in the Play! emulator....
The real thing hooked up to a small VGA monitor and rotated sideways (so I can test it). This was of course, after I fixed it as it was
previously dead. I also fixed ALL the other S147/S148 boards I have here (16). They all had the same common fault LOL!
This is Umimonogatari Lucky Marine Theater / Sea Story. These are just FYI, no further emulation progress will be attempted beyond this as
it's a mechanical coin pusher....
I just completed dumping Pacman Battle Royale today so hopefully there will be some progress shown here soon. That completes the dumping of
games on S147/148. As far as I know there are no more games made for this system that could be emulated and be playable with the exception of the following...
- Pacman Battle Royale Tournament Edition (same game with minor tweaks). Pretty rare and unlikely to be dumped.
- Pacman's Arcade Party Home Edition. Has one additional game, Ms. Pac-Man.
The last one should be achievable one day.... as they all begin to slowly die they will be sold off as 'untested' LOL!
There are possibly a couple of other random medal or coin pusher games but they are rare and rubbish anyway. If you know of any other 'good'
games on S147/148 let me know. Otherwise that's it for this system and it's time to move on.
27th April 2024
Over the years I've had many junker PCBs given to me for parts to fix other boards. Here's one specific example that has been laying around
here for probably 10 years. If you're a Simpsons fan you might want to look away as there's a high possibility you may become violently sick
and eject noxious liquids and semi-solids from all orifices at both ends....
Yes that's a Simpsons board!! This is a good example of just how many really stupid, clueless and brain-dead people are in the arcade scene.
This was hacked to hell and back by the king of all loser cowboys thinking he could fix it with a hammer LOL! It needs to be saved and
luckily it came to me so it has a chance. Of course a board in such bad condition will require weeks of work and might remain dead after
all that work but I will try my best to bring it back from the dead.
I worked on the board about 1 year ago for a few weeks. The reason for not putting the log here is because it still wasn't working at that
point and I didn't want to spend several days writing up the repair log. Now it's time to write the repair log but I'm not going to detail
every little thing here. It really just needs all the missing parts replaced and all the Fujitsu logic chips replaced with good chips (all
removed/tested and several were found to be bad). Then the *actual* faults need to be fixed (which I'll detail here) but I really don't want
to write a book here and it's not easy to remember everything, especially in the same order that it was done. Let's just skip all the
part-replacing b.s. and show some pics of the re-assembled board in its current state along with a few work-in-progress pics. Or at least
the pics I took (and just found) from a year ago. Click on the pics and read the pic descriptions to see what was done....
There were also numerous broken traces created by the king cowboy loser and those were also patched. That was done by removing parts and
physically tracing the copper trace on the board from end to end. I had all except one custom chip from this same board in a box and those
were simply put back onto the board. After everything was replaced and the damage fixed, the backgrounds were still missing. It turns out
that the Konami custom chip 051962 was bad. I replaced that chip with one taken off a different board (Punk Shot) and that fixed the
backgrounds. THAT was the actual fault on this board, a bad 051962 custom chip.
As of about May 2023 this is what I currently have and it's been sitting there on a shelf waiting for parts....
The right side of the board (butchered part) has not been touched yet because without that (missing) custom chip there's not much point. The
missing custom chip is part of the sprite circuit so without it there are no sprites. On the ROM check screen the red errors are the four ROMs
on the right side. Additionally the sound is working fine.
Forward almost 1 year and another Simpsons board came in for repair. This had the usual Fujitsu logic faults. After the Fujitsu logic chips
were replaced the board booted to this screen....
.... and this is what it should show....
The bad graphics are caused by either bad ROMs (two bottom ROMs) or a bad custom chip, either 051962 or 052109. The two red errors are the
sound ROM and sound RAM. That's because the Z80 that runs the sound program isn't running. I went over the entire sound circuit and
removed/replaced all the Fujitsu chips and also replaced the sound RAM, sound ROM and Z80 CPU, as well as pretty much every other chip in
the sound circuit including the custom sound chip at the top which was taken off another working board. I even removed and tested every
other non-Fujitsu logic chip in the sound section in case any of them were bad but everything tested ok. I did a thorough trace of the
entire sound section using the schematics as reference (many hours of work) but everything was connected like it should be as per the
schematic. The last two (bottom) errors refused to go away and the Z80 refused to run. I was almost getting ready to give up. I checked the
graphic ROMs and they were ok so the final executive decision on this board is it looks like one of the custom chips is bad. I don't think
the sound problem is impossible to fix, just that it needs a lot more time. The board is definitely not scrap and I can always go back and
look at it later. Now I have another dilemma. A little voice in my head is telling me to take that gfx chip from another board and try my
luck with spending more hours attempting to fix the no-boot sound fault. Another little voice is telling me to take the other chip I need
from this board and move it to the working board. The latter is what was done. The board with the gfx and sound fault is now missing Konami
custom chip 053247. If I ever get another junk Konami board containing that 053247 chip (or someone sends me any Konami junk board with that
chip on it) I can move it over and continue looking at the remaining faults on that board. For now the sprite chip was removed and mounted
onto the working board. Of course just moving a chip over didn't help anything and there were still no sprites hehe! That's obviously
because of all the damage on the right side of the board. Now if you know anything about The Simpsons PCB you will know there is a manual
with schematics but the two video pages for backgrounds and sprites was purposely omitted from the manual. I'm not really sure why as there
are some games around the same time that do have full schematics and the chips used on Simpsons are also on those other schematics. Meaning
the pinout is known and their basic functions are known. While not absolutely required to fix this I figured why the hell not, so I made
schematic pages for the video section. But with a special twist. The pages are not only re-drawn but done using the same Konami style from
1991. In order to do that I had to create a lot of custom schematic symbols. I also copied the logo and the title block and sheet border and
added signal names and across-sheet references for those signals. Additionally, Konami schematics show the custom chips as very long
rectangles but in order for it to be more useful as a repair aid I drew the custom chips as they are presented in real life, as squares and
with in-order pin numbers. After about 2 weeks it was completed. The pages are named VRAM, which is the background page, and OBJECT which is
the sprite page.
With the video schematic pages in hand I checked the entire circuit finding several broken traces. As I patched each trace the
MASK ROM test slowly got better (then worse hehe!) then better again until only 1 ROM was showing as bad (actual ROMs are tested good)....
This is the really funny part. That king cowboy loser pulled all the 74LS374 logic chips on the right side, added sockets with soldering
skills at the level of a retarded ant and put them back into the board, breaking a dozen traces in the process but also putting back BAD
CHIPS!!!! LOL!!! Additionally he left all the Fujitsu logic chips untouched, not even making any attempt to find the real fault! Wow, what a
triple f**king LOSER. I would have added 'brain-dead' too but that guy doesn't have one LOL! I knew exactly which chips were causing the
issue from my schematic but it actually doesn't take more than a normal brain to figure it out due to the pattern of how the ROMs are
connected to the logic. Data pins D0-D15 of MASKROM 16L (the bad ROM shown in red) is connected to the 2x 74LS374 logic chips at 10K and
12K. I manually beeped out all the pins on both chips for continuity and they were all connected. I pulled both chips and one failed....
These 8x 74LS374 logic chips were not all the same brand so it appears some of them were changed. It's highly possible the original chips
were not Fujitsu brand and were ok. Or maybe they were all Fujitsu and these chips are the replacements. It's highly likely there was
actually nothing wrong with the sprite section and the only fault was some bad Fujitsu logic chips and a bad custom 051962 chip. Either way,
with the bad logic chip replaced and all the damage repaired the board is finally fully working :-D
Now I know what you are thinking... the schematic above doesn't have a link and I didn't make the full schematic available publicly. Yes I
know, I'm just screwing with you ;-)
Since you have stayed with it and read to the very end of the repair log I'll reward you with the actual PDF schematic. For a hard copy it
should be printed on A3 paper with each page on the same piece of paper using both sides to print both schematic pages. Then fold in half
and insert into a Simpsons manual along with the other schematic pages. This should be complete and I have no plans to re-check this and
make corrections, but if I do find any other errors or omissions it will be updated and the version changed on the schematic. The current
version is dated April 9, 2024 and is available on my Reverse-Engineered Parts and Documents page. Enjoy it and be sure to let other
Simpsons fans know about it while pointing out where you found this holy grail ^_^
23rd April 2024
If you have been following along with previous repairs you will remember some Police Trainer PCBs that I worked on around July 2023. They
seem to have a common issue where the reset chip (Dallas DS1233 Econoreset) just dies and then the board doesn't boot. I wanted to try to
replace that special and not-common DS1233 with a common capacitor-resistor reset circuit but it didn't work. This board requires something
different timing-wise. After doing research and some Spice Simulations an electronic engineer friend and I came up with a circuit that does
what the DS1233 does but using only 3 common and cheap components. To test the theory I built the circuit with loose through-hole components
and wired it up point-to-point. It was very ugly but it worked. In a recent PCB order I made up a small PCB (10mm x 5mm) using
surface-mounted parts, ordered the one part I didn't have in stock and built the first one today. It works perfect and the Police Trainer
board boots up without any issues. Here's a quick pic of the circuit in-situ and the schematic.
It uses the familiar cap-resistor components (values selected to give the correct timing) but also goes through a 74HCT14 Schmitt-Trigger
Inverter which is the key to making it work. The 7414 is also available in a single gate 74HCT1G14 which is the part I used on the little
PCB. It's designed in such a way so that the VCC and GND pins fit across a SMD capacitor. The Police Trainer board has several not-populated
capacitors so that makes for a nice clean mounting. Since it's at 90 degrees to the reset pad on the board I just soldered a short wire from
the IC output to the reset input point but the PCB I designed also has a dedicated reset output pad so it can be mounted flat on the PCB or
some header pins can be added and it can be built like a TO220 or TO92 package. Additionally there is no copper or vias on the bottom side
of the little board so it can be mounted directly onto the PCB (as shown above) without any risk of shorting anything :-)
21st April 2024
A Namco Final Furlong came in for repair from one of the big Australian arcade distributors. Like most companies nowadays who need people to
deal with the general public, it looks like they don't employ any real tech people and just take any random clueless dog off the street who
will accept minimum wage lol! They only sell stuff from a warehouse so if anything needs to be tested they send it out to someone who can
test it. That was not me but it ended up coming to me via someone local hehe! The board worked fine after just cleaning the connectors and
re-seating the boards so that was a waste of time LOL! However while I'm in this mode I figured it was a good time to look at some of the
other junk Final Furlong boards that have been laying around here for over 15 years. Many years ago several were purchased trying to get a
full system to dump (they were all partial junk lots). The first one arrived on October 28, 2008 (Wow 16 years ago!). Another one arrived
August 15, 2009. I didn't see any others in my arrival logs but there were some others too. At one point I had 6 or 7 of them here and only
1 worked. Eventually a full dump was done and then they were put on my shelf. Here's a quick pic of the first (partial) board that arrived
in 2008 and a pic of the main board without the ROM board on top....
Now it's time to try to figure out some of them. Well actually over the years I fixed a couple of them but I didn't document it
here heh! One board that came in for repair about 1 year ago was a non-working Japanese Final Furlong FF1 board. It was being operated so
it looked like new and had no physical damage. The boards are bolted into a metal rack so they generally don't have loose legs on custom
chips or random loser PCB damage. That means some random chip has failed. I couldn't fix it so I just swapped one of my working FF2
(English) boards and I kept the Japanese version board which will be dumped later. If Final Furlong was to suddenly start working in MAME
that might persuade me to dump it sooner, rather than later ;-)
These boards are incredibly flimsy and complicated so it's important to first understand what the board is supposed to do when booting. At
power on there are 8 LEDs that light up. They are connected to the outputs of a 74HC374 logic chip with all the 74HC374 inputs tied to the
backup RAM databus D0-D7 and also the C361 custom chip. BTW, this is also how the LEDs are connected on Namco System 23 (Time Crisis II
etc). If the backup RAM is bad, no boot, no LEDs. If the C361 custom is bad, no boot, no LEDs. If the top ROM board isn't plugged in, no
boot, no LEDs. If literally *anything* in the CPU section is bad, yup you guessed it.... no boot, no LEDs ;-)
So with all the LEDs lit up (meaning some quick checks and security pass) they slowly turn off one at a time until all are off. I believe
during this time the main program is being uploaded to the program RAM (2x 1M x16-bit SDRAM) which is configured as 1M x32-bit. That data
passes through more than a dozen logic chips then into the C413 custom chip then into the SDRAM. Then the main program starts running. At
this point the LEDs flash left/right like KITT (from Knight Rider TV series). After moving left/right about 12 times an IC check screen
shows briefly. This is a really quick 'life' check of several RAMs and custom chips. If everything on that screen passes it changes to
another check screen and does some deeper tests (not shown) with the result shown as OK. After everything on that screen passes the game
shows the Namco logo and then the title screen.
This board I'm currently looking at does the LED count down and the LEDs move sideways but nothing happens after that and nothing shows on
the screen. The LEDs just keep moving left/right forever. That's actually a good sign and means the board is still running. If the LEDs stop
moving it means the board has locked up and crashed, and of course there will be no clues given by the hardware about what or where the
fault is. I'm guessing this is why Namco added more extensive start-up checks to System 23 to aid with factory testing and that also helps
when repairing too but no such luxuries with Gorgon. Due to the ROM board being on top there's almost nothing that can be checked except the
area on the left side....
By pure luck when I pressed on that area I saw the first 'life check' screen!
I'm guessing there are some loose legs on the custom chips there so I went over them and sure enough found several loose legs and resoldered
them. I powered on again and now that check screen shows without having to press on the board but it's the same. There are a couple of
errors shown on the C417 custom chip RAM at 12R. I've been slowly working on all these boards over the years and noticed that RAM has
already been changed. I checked the C417 custom chip and found some loose legs so I resoldered them. Now the first test screen has no errors
and the next check screen shows....
Now I'll give you a brief explanation of this screen based on what I know (which isn't a lot lol)....
MEMORY is likely to be the main SDRAM. This is kind of stupid because if it was bad the game would be dead ;-)
TEXT is the custom C361 chip or RAM connected to it. FYI the C361 has RAM inside too (shown on the first start-up screen as location 10B). If
C361 is dead or missing the board does nothing and is dead.
PALETTE is the custom C404 Palette/Gamma chip (which btw, has RAM inside it ^_^) or the 3 RAMs connected to it.
SPRITE is the sprite chips or the RAM connected to them. I'm not exactly sure what it's checking here. There's at least 5 sprite-related
custom chips, several with RAM connected so best I can say is it's one of more of those custom chips C300, C374, C379, C381, C397 or
connected RAMs.... with most of them covered by the top board so good luck trying to figure out any sprite custom chip faults or sprite RAM faults ;-)
POLYGON is the C417 custom chip or any other 3D chip including C435 or the RAM connected to it/them.
This is where the error is but I actually already know why it stops here LOL.....
Yup! I took those 2 custom chips when repairing something else years before. I suppose it's time to put them back with some others taken off
another junk board. In this case a totally butchered Time Crisis II board where some f**king idiot cowboy loser tore off the R4650 CPU
taking half of the PCB pads with it LOL!
With the 2x C435 custom chips replaced it now shows this WAIT message....
I believe this is a non-fatal error simply because the backup RAM is not powered with a battery. I put a CR2032 battery into the holder and
power-cycled the board. All the tests on that screen say OK and the game booted. However the screen is really whacked....
I left the board for a day and had a think about what the problem could be. It was definitely a pretty serious failure of something
since there was a LOT of missing data. The next day I decided to get my 8X magnifier and go over the board looking for anything unusual. It
didn't take long to remember that these boards were junk, tossed around by losers years earlier and all damaged slightly on the bottom.
There were a lot of scratches and all looked ok until I found this....
Oooff! It looks really bad but there was actually only 1 broken trace. I patched it with some micro wire and powered on....
Wow it's A LOT better now. The 3D looks ok but the textures are bad.
There's a large number of RAMs on the right side of the board used for the textures and none of them are tested. I pushed on that area
by squeezing a finger between the main and top boards and pushing down and some of the textures looked good! I first soldered the 6 RAMs
closest to the corner. It fixed the issue but only on the right side of the screen....
I pushed on all the other RAMs but it didn't change anything. I thought about trying to manually solder the other RAM there but they are all
very close together and SOJ RAMs are annoying to solder by hand so I decided to do a full hot air reflow of all of the texture RAMs. That
fixed it!
Well almost lol! Now the area on the right side is bad again and the rest of the screen looks perfect hehe!! I reflowed those same 6 RAMs on
the corner and that fully fixed the graphics....
Now it's time to relax a bit and play it :-)
Well it's pretty hard to play it with two 5k-ohm pots lol! This is kind of a kiddie ride really. I doubt anyone can actually win. Plus they
also cheat and bump into you so you lose energy. I had it set on easy and the best I could get was 5th.
On to the next board. I previously worked on this one around June 2023 and I don't remember what I did to get it to this point but it was
probably just soldering a bunch of loose legs on custom chips or maybe changing some faulty RAMs. I found a couple of old pics showing the
board hooked up to my test harness and a cut trace I repaired near some resistors. Those resistors are on the bottom side of the board in
the video output section under the Sony CXD1178Q 8-bit 3-channel RGB video DAC. It currently shows jumbled garbage on the start-up screens
with the text shifted up about half a screen, then it hangs on the 2nd test screen (with totally unreadable text) but if I press test then
release it the game starts. On the title screen there's a lot of O's on top of everything. In game the 3D and textures are bad. ...
I'll skip the part where I waste a couple of weeks pissing with this and show what was actually wrong with it....
Yup! Another damaged trace caused by a cowboy loser. I patched that with a micro wire and that fixed everything hehe!! I won't bother
showing an in-game pic as it's exactly like the working one above. The broken trace joins to the C361 (pin 75) which generates the text
layer (and of course several other things like h-sync and v-sync). I checked my schematic and the actual signal on that previously broken
trace is A10 on the backup RAM, so while that RAM is used to save high scores it's also used for *LOTS* of other things :-)
Here's another quick log for a repair that was done around the same time (June 2023). Again I don't remember exactly what was done other
than what these old pics show. One of the PST575 reset chips is missing and a resistor on the bottom was knocked off (the green wire is a
factory bodge wire which is on all Gorgon boards). I replaced the missing parts and it booted but with lots of in-game graphical faults. The
actual fix for this was changing two RAMs at 4P and 4N, and probably also re-soldering a bunch of loose legs on the custom chips. This was
done when the Japanese board came in for repair. The one board I had that I thought was working actually didn't work so I had to go through
the junk and find one and fix it. This board was the one that got fixed and went back to the owner/operator. He got a nice 'upgrade' to the
English version :-)
Later at the same time I fixed another one so I could have one here working for testing purposes. I currently have 3 fully working Final
Furlong boards sitting on my PCB rack. There's 2 more that don't work. One is the Japanese version mentioned above which not only has a bad
main board but also a faulty ROM board showing bad graphics. Those are totally dead where the LEDs light up and start to move sideways but
stop moving and lock up without displaying anything on the screen. It seems to be sort of common as I've seen several that do this. I
haven't figured out what's causing that so far but if/when I do I'll make a log about it here.... although it's very low priority given I
already have 3 working boards :-)
15th April 2024
I went through my boards and found another Subsino game that was dumped years ago (Last Fighting, a Bomberman rip-off) with a dirty
little secret DS2430 which is now dumped and should be added to MAME soon :-)
This board is not working because the H8/3044 MCU was sent off for decapping many years ago. Unfortunately it was not done but now that I
know a bit more about these boards I realised I probably have several of the same chips on the recently dumped Subsino mahjong boards.
This is the chip from my Decap List, chip #108....
It is marked "SS9689" which matches the MCU on the mahjong boards. I took the chip off and mounted it onto the Last Fighting
board, powered on and it works. Wow! I never thought I would see this board working again hehe!
Now if the person who still has the MCU (I believe it is CAPS0ff) can decap and/or dump it, the MCU dump can be added to all the games that
use this same hardware. Alternatively I can look into dumping the chip here as it seems like it can be wired up like an EPROM and dumped
non-destructively using a similar method I used to dump the SH2 CPUs back in July 2023. I'll probably make up a special custom Guru dumping
adapter board to make the job easier, but first some research is required.
In other news, a couple of months ago I noticed an unknown Namco System 147 board on the bay, but of course it is known to me hehe! It is the last remaining
and *interesting* S147 board that is not dumped..... Pacman Battle Royale. It's a modern 4-player Pacman with enhancements played on a 16:9
large LCD screen cocktail cab. Thanks to long time MAME contributors ekorz and rtw it was promptly bought and shipped over. I powered it up
using the same I/O board that came with Pacman's Arcade Party and it actually works fine. So the seller was basically completely clueless
with no idea what the game was or how to make it work lol! This board also requires an additional A.I. PCB I/O board that is used to control
all 4 player directions so without that board it won't boot into the game but hopefully it can be made to work in the emulation when that is
eventually done.
12th April 2024
If you have been following along with recent dumps and MAME progress you will know the graphic ROM from Xiaoao Jianghu hasn't been dumped
yet. That's because it's a very unusual 32-bit ROM in a SSOP70 package. It's possibly the first and the only 32-bit ROM ever found on
any arcade PCB. After some PCB reversing and research I got the pinout and tried to dump it manually but all those wires (70 of them!) were
frying my brain. Having worked in engineering for ~30 years I came up with an idea pretty quickly so I got to work designing a custom
adapter and added it into a recent PCB order which arrived a couple of days ago. This should allow the ROM to be hooked up more easily
without having to deal with 70 loose wires. The arcade board can use 4x 1MBx8-bit EPROMs (D0-D7 on each ROM) or it can use this strange ROM
that is 1MB x 32-bit (D0-D31).... which also equals 4MB x8-bit... which by pure coincidence is the same capacity as the 4x 1MB EPROMs
:-)
My reversing revealed when the SSOP70 ROM is used 8 bits (in order, x4) go to each of the positions where the EPROM data pins D0-D7 were. So
ROM0 (D0-D7), ROM1 (D8-D15), ROM2 (D16-D23) and ROM3 (D24-D31).
Since there is absolutely no support for any 32-bit ROMs in any EPROM programmer I figured the logical way to dump it was to hook up the
first 8 data pins D0-D7 and dump it, then hook up the next 8 data pins (D8-D15) then dump it again, repeating for the other remaining data
pins D16-D23 and D24-D31. At the end there should be a full 4MB dump once the 4 separate dumps are joined together.
Here's a pic showing the custom adapter I made with it hooked up to D0-D7. The theory was I just had to move the 8
wires to each header near the ROM and dump it as a 27C080 with 4 reads to get the full dump.
As to whether it worked or not, thanks to quick work by Osso hooking it up, I'll just let the resulting emulation speak for itself ;-)
27th March 2024
The Golden Axe board that was fixed February 21st 2024 is back again hehe! When cold there are white vertical stripes across the screen and
when it warms up the whole screen turns white but the graphics are visible behind it because the screen has horizontal lines missing.
There's also some minor glitching on the sprites (missing dots/lines)
Running the test mode 'memory check' shows all RAMs are good. But when it gets to checking the color RAM the screen *almost* fixes itself!
Now it looks ok but there are tiny horizontal lines across the screen....
So it's the color RAM, right? I swapped them but it didn't change anything LOL! This is another one of those bizarre faults that is likely
to be very difficult to find. I swapped over a working ROM board but the fault remained although the sprites looked slightly better. The
fault is definitely on the main board but the ROMs have issues too. I checked the ROMs and found one of the black mask ROMs at B7 was
actually bad, giving pin contact errors on pin 10 when I read it and multiple reads gave a different CRC32 so this ROM is definitely bad.
This is a known thing now... mask ROMs are dropping like flies and it's only going to get worse as time passes. I swapped that out for an
EPROM programmed with the correct data and it seems to have made the sprites look better but it didn't fix the white screen problem. I
plugged the ROM board into a different working Golden Axe main board and it looks perfect so the ROM board is 100% ok. It is important to
narrow down the fault to a specific board because you don't want to be working on a board that isn't faulty as that just wastes time and can
create more problems by messing with something that doesn't need to be messed with.
As they say, if it ain't broke don't fix it ;-)
System 16B has 3 big custom chips that do almost everything.
315-5195 - CPU related functions, memory controller, main glue logic etc. If this is bad the board will be dead.
315-5196 - Sprite Generator
315-5197 - Tile Generator
There's also a few logic chips (74LS244/245/374) that separate the various buses. Since the RAM passes it looks like they are ok but the
actual RAM test is likely to be very simple because it's fast (meaning it does/checks almost nothing) so it doesn't reveal a RAM that could
be marginal. These boards are also annoying because the top ROM board has to be in place otherwise it only shows a black screen so probing
has to be done on the back side of the main board. I probed around and eventually came across the 6116 (2kB x8-bit) RAMs at G2, G3, G4 and
G5 which appear to have a stuck pin 22 which is A9. I suppose it would be a good idea to consult with the schematics to see what those RAMs
are doing....
The schematic shows they connect to the custom sprite generator chip 315-5196 and pin 22 is actually grounded so that's normal. These RAMs
are connected in pairs. When shorting various adjacent pins together I noticed when pin 22 was shorted to pin 21 on RAM G4 or G5 the white
lines completely disappeared!! The sprites were of course fully glitched with horizontal lines because pin 21 is the RAM write enable
pin....
At this stage it looks like either RAM G4 and/or G5 is bad or the custom chip 315-5196 is bad. I don't see anything else involved but just
for a test I piggybacked all of the logic chips and all of the RAMs one by one (extremely annoying having to remove and replace the ROM
board 50 times) but piggybacking didn't make any difference. I pulled and tested the two RAMs. The RAM is tested in my chip tester by
writing (binary) 00000000, 01010101, 10101010, 11111111. In hexadecimal that's 00, 55, AA and FF. Then it goes onto more exhaustive checks
including count+/-, RND(256) and March U and March Y tests. If all of the tests pass you can be 1000% certain the RAM is good. The RAM at G4
failed but not immediately. It passed the 00 write but failed on the 55 write. I replaced both RAMs for known good chips and powered
on....
It works!!! This is another lucky board that lives to play again. Game NOT over heh! So there's something to learn from this, never trust the
built-in RAM test because it is almost always very basic ^_^
Now we can use this to check something in MAME. MAME ROM set goldnaxe3 has a comment in the source saying the ROM check fails on two ROMs.
This board is the same version so I checked it in the test screen memory check and it says "GOOD" for all ROMs. I read the ROMs and they
match MAME. So that likely means the decryption key for that set using 317-0120 FD1094 CPU module has to be bad and someone needs to check
the decryption key file.
25th March 2024
A Sega System 16A Shinobi board came in for repair.
The game is running with correct sprites but the background graphics are messed up. This board has a lot of Fujitsu logic chips. I went into
the test screen and ran the memory test and all RAMs passed. Unless you're very familair with this hardware (I'm not) there's no easy way to
find this problem but I figured it was probably on the bottom board. I probed around and found the background RAMs by shorting data lines.
This is the general area to look. I used my logic probe to check many chips (mostly focussing on the Fujitsu chips) and when I got to IC82
(74LS244) I found a totally dead no-signal on pin 15. I piggybacked it and that brought most of the graphics back so I pulled and swapped the
chip for a known working chip....
I powered on again and it was exacttly the same as before! I tested the old Fujitsu chip in my chip tester and it passed. I probed the chip again and
when shorting pin 15 to pin 14 it brought up the same almost-fixed screen. Pin 15 was still dead with a completely missing signal so it had
to be a broken trace. I had a quick look at the System 16A schematics. It's the usual poor quality crap done by the usual clueless cowboy but maybe
I'll be lucky.
The schematic shows pin 15 is an input (AD8). Checking the other pages doesn't show where these lines go because the other page is
chopped off on the left side! Yeah good work buddy! I manually traced it and found it went to a via just above the logic chip. I traced that
and it went no where so this is definitely the bad trace. This area of the board is a bit weathered. Scratching off the mask revealed a tiny
break in the trace. Tracing the other side shows it goes to 315-5012 pin 8 and all the other inputs from the 74LS244 at IC82 also go to
the same Sega custom (pins 4-10). I patched the trace, powered on and it's working ok now. That was a lucky one as it could have been a lot
worse.
21st March 2024
Some more Mahjong work-in-progress thanks to quick work by Osso....
Shizhan Sanguo Ji, GMS, 1998
20th March 2024 .....it's sleuthin' time!
While working on the last mahjong board dump I noticed a comment in the MAME driver (subsino2.cpp) that there's supposed to be a small
(unknown) EEPROM on the board but it's not dumped. The comment says it's used for protection and uses a 1-wire circuit to read it. I pulled
out my Bishou Jan board and compared it to the Xiao Ao Jiang Hu board....
They appear to be *identical* other than these minor differences...
- The teft board has a surface-mounted SSOP70 ROM, right board has 4 EPROMs. Under those EPROMs is the SMD pads so either can be used. I'll dump the SSOP70 ROM later after I figure out the pinout.
- The left board has a JAMMA connector and (earlier) 18-way Mahjong connectors and the right board only has the 28-way Mahjong connector
(JAMMA is present but masked off/unused).
The bottom right side of these boards has a bunch of parts that are not populated and they are both the same so that's normal. There's also
a Hitachi H8/3044 microcontroller (has 32kB internal ROM) but there's an EPROM on the board for it. If there is internal ROM it's not
important since the emulation is working as-is without it. Checking over the entire board didn't reveal any other obvious visible EEPROM so
where could it be???? After some extensive searching I found something hiding in the sound section with the surface scratched off!!!! Now
that looks suspect LOL!
It's masquerading as a transistor hehe!! The PCB even identifies it as Q3. I don't think so, bud ;-) The driver comment says the program
sends an identify command and when that passes (Device ID=14h) it reads out 64 bits of data. Experience tells me it might be a DS2430 and I
have previously dumped these devices. The datasheet says with the flat side of the TO92 IC facing me, pin 1 (ground) is on the left.
Checking the pins on the PCB shows pin 1 is tied to ground, pin 3 is tied to a resistor (removed by me in the above photo) and pin 2 is tied
to the 2SC945 transistor behind it. After looking through some Dallas 1-wire databooks I found the Family Code for the DS2430 is 14h. I
suppose the Family Code and Device ID is the same thing so that's a match. It's time to test the theory.
I first checked to make sure I'm barking up the right tree. I removed the 10K resistors (which connect the IC to a Subsino custom chip) and
powered on. With R4 removed the game still works but with R5 removed it now only shows the following screen....
This means the protection check has failed.... looks like I'm on the right path hehe!
I pulled the IC and plugged it into a random socket into pins 1 and 2 as instructed by the info that my EPROM programmer gives. It gave a
good read so I repeated the process with the other board....
btw, the same DS2430 IC is inside some Konami DIN5 dongle plugs used for protection and can be dumped the same way.
I tested Bishou Jan in MAME using my new dump and the game works so that proves the dump is good.
So the secret IC is just a DS2430.
Anyway, job done and mystery solved :-D
In other news, these just came in thanks to quick work by Osso....
San Se Cai Shen (Three Color Plutus). GMS, 1999
19th March 2024
Here's some more mahjong work-in-progress thanks to quick work by Osso.
Jin Xiu Zhong Hua (BMC 1996) (dumped. preliminary, not working yet)
Update: The remaining Mahjong boards have been dumped.
Check the PCB Arrival pic below (in the news 18th March) to see the boards identified.
WIP pics here soon, maybe....
18th March 2024
A bunch of Mahjong boards arrived, thanks to Dyq and little0.
A lot of these are on very unusual hardware. They will be dumped over the next few days although one of them might take a week or two to
figure out. I dumped one quickly that looked like it might be an easy addition; Being an IGS game there's the usual protection causing issues but here's a couple of early work-in-progress pics
thanks to quick work by Osso....
Chaoji Da Man Guan 2 Plus, IGS, 2000
Update: I just dumped another one of the Mahjong boards for a game named "Tong Zi Maque". It's the small yellow PCB on the bottom left of
the pic above. The main program ROM doesn't contain any valid Z80 code and there's no plain text in the ROM. The ROM and Z80 databus are
connected to a CPLD so it's highly likely it's encrypted and emulation is not possible. At least not anytime soon. Just a FYI ;-)
I also wired up the board but it's not working, just showing a bunch of garbage on screen. There's not much to the board, 2 big square PLD
chips, some ROMs and 2 RAMs. The RAMs had a bit of corrosion on them from a leaky nicad battery (one RAM is battery-backed) so I pulled both
RAMs and they tested bad so I replaced them hoping that it would start working but it's still dead. There doesn't sppear to be anything
else wrong with the board so highly likely this died due to losing the battery-backed decryption key which likely was inside the DS12887 RTC
module.
10th March 2024
Firstly some dumping-related news. In that large pile of Namco System 147/148 boards was a System 147(B) version of Animal Kaiser which I
dumped a couple of days ago. It was quickly hooked up in the Play! emulator and appears to be working ok. The dump was Version 1 (shown on
the title screen as just 'Animal Kaiser') but it appears with a simple ROM byte change all 6 versions can be made to show. The other
versions would have been enabled with a special card scanned in the card reader and then a byte in battery-backed NVRAM would have been
written there to configure the version that runs. So basically Namco designed this game complete with 6 versions already done so that they
would be able to sell numerous nearly identical versions of the same game with zero effort to maximize profits LOL!
I've also dumped Pacman's Arcade Party but that hasn't been looked at yet by the Play! emulator guys. Hopefully soon I'll have some
work-in-progress pics of it.
Now onto a repair. Since I now have a working Zero Point board for reference it would be a good idea to try to fix a
dead Zero Point board that's been laying around here for over 10 years. This one is dead and shows a screen full of garbage. It's missing
the audio amp and another 24 pin chip (Yamaha YM3812) which I replaced before taking the folowing pic....
But before I do that I wanted to point out a small modification that needs to be done on this game when being used in a JAMMA cabinet.
Check the following pic...
The speaker hook-up on this board is non-standard. It is able to output to two speakers. As far as I know it's just dual mono, not a stereo
output. The original amp has two inputs and two outputs but both signals appear to be identical. Anyway, when connecting a standard JAMMA
cab to the board I previously fixed, the sound was muffled/distored slightly. I thought it was a side effect of using the alternative
amplifier IC but it's an actual fault. According to the manual the JAMMA speaker+ pin is the same but the speaker- pin is NOT ground, it's
speaker2+!!! A ground has to be connected separately to each speaker from a proper ground location. If not the sound is distorted due to the
speaker- not being ground. I can bet a lot of operators back in the day didn't realise that and just used it as-is and just thought the
sound was crap on this game or didn't even notice the distortion hehe! To fix that permanently I cut the trace to the JAMMA speaker- pin and
joined the other end to ground so now the sound is clear and loud :-)
The 68000 clock and reset signals are present. Most of the logic is dead so this is a very difficult problem to find. I'll omit the part
about randomly probing around for half a day and getting no-where and skip to how I found the issue. There are 4x 74LS245 chips located just
above the 68000....
The chip on the right (closest to the 28 pin RAM) is directly connected to the 68000 and that chip connects to the 74LS245 to the left of
it. Those 3x 74LS245 chips on the left side are all disabled due to the signal on pin 19 being completely missing. It's not high or low it's
just not there. That is of course an obvious fault since that pin should be either high or low or pulsing high/low. Pin 19 is the active low
enable so it has to be low otherwise the chip does nothing. I traced pin 19 and it connected to a 24 pin PAL labelled "04". PALs generally
have inputs on one side (in this case pins 1-11 & 13) and outputs on the other side. Probing the PAL shows the input side is active but all
the outputs pins are dead. I pulled the same PAL off the other working Zero Point, fitted a socket, plugged it in and powered on. The
display was slightly different but not by much so that didn't fix it. However the PAL was now active on the output side. I was randomly
probing around and touched the PAL near the (previously missing) YM3812 labelled "02" and the graphics on the screen changed. Inspecting
that PAL revealed someone had been playing around in that area and desoldered the PAL, but then just put the PAL back into the holes and
didn't solder it in. It was just sitting there floating LOL! I soldered the PAL in, powered on and this came up....
Wow! The graphics are messed up but it's working!! Ok well I guess I'll have to try to backup that PAL at some point but for now I'll leave
the good PAL in there and try to fix the remaining faults. This board has a bunch of square CPLD chips that are used to generate the
graphics. I pushed on the chips and sometimes the graphics showed on screen. This is of course a common issue with large square chips in
sockets so I removed all the chips, cleaned the legs and socket and put the chips back. That appears to have fixed 99% of the
faults....
I swapped all the square chips from the working board to the faulty board and it didn't make any difference so I put them back. The sprites
are good so the problem is on the backgrounds only. Sometimes when it booted there were vertical lines on the screen across all the
backgrounds but sometimes most of the vertical lines were gone and it was 99.99% good with only a few random pixels out of place. Pushing on
the board sometimes partially fixed it but sometimes made it worse. When lightly touching the square chip above ROM 5 the lines almost went
away completely. This means the problem is not a chip but more likely a bad connection or partially open via, likely due to corrosion. The
lower right side of the board is not in great condition and the bottom side looks even worse with a lot of potential track rot. The square
CPLD chips previously had a bit of water damage on them so there might be some corrosion either under the square chips or under the ROMs.
Like usual that probably happened after the board died from the bad PAL and was thrown in a damp shed by the usual cowboy loser. I suppose
I'll have to remove all of that stuff and take a look. I'm definitely not going to spend days/months on this but I'll give it a few hours
and see what happens. I started by removing the square chip above ROM 5....
There's no damage under the chip. Some of the nearby vias look slightly corroded but they all connect to the square chip. I traced all the
pins on the background ROMs. It looks like a single square chip doesn't have enough pins to handle all 4 ROMs so two chips have been used.
The top two ROMs 5 and 6 connect to the top square chip and the two bottom ROMs 7 and 8 connect to the square chip immediately to the left
of those ROMs. These ROMs are equivalent to 27C160 EPROMs. Check the pinout below. Roughly they are connected like this...
To diagnose it roughly it's not necessary to know where the connections go, only that those pins for each ROM connect to those square chips.
With all the data pins traced, everything was connected except ONE pin... ROM 6 pin 20 which is D3. This would be much more difficult
without another working board but since I do have another working board I checked the ROM missing signal on my good board and found it is
supposed to connect to the top square chip on pin 47. The first pic below shows that signal routed to ROM 6 pin 20. The via just above
ROM 5 pin 23 is connected on both sides and is tied to the square chip so the trace on top that runs under the ROM sockets is broken somewhere.
I'm not going to remove the ROM and patch the trace so I just added a wire on the bottom side of the board joined to the via and the ROM 6 pin
20 then powered on....
WOW!! That fixed it and now everything is perfect. It was really just luck that the damage was isolated to only one pin.
I found a uPC1241H amp chip, soldered that in and sound is perfect too so now I have two fully working Zero Point boards :-D
3rd March 2024
A few more Namco System 147/148 boards arrived.
2 more junker Animal Kaiser boards and (FINALLY!!) one of the good games on this system.... Pacman's Arcade Party, which is basically PS2
Namco Museum 50th Anniversary. The owner asked me to look into repairing the Pacman board since it is currently dead so there might be a
future repair about it.
Of course they're all non-working due to having crap blown over the board from the fan and then it corrodes and dies.
Remember to keep your boards clean, people!
Update: Fixed the Pacman's Arcade Party board and ALL the other S147/S148 boards I have here. They all appear to develop the same common fault LOL!
I'm still looking to get hold of the last remaining known good game on this system.... Pacman Battle Royale. It's a cocktail type cabinet
with 4 players on a 16:9 screen with modern and enhanced graphics. There are extra power-ups including one that lets the player eat the
other players hehe! Looking at vids on youtube shows it's a really fun game so we need to get hold of it before they become extinct.
If you can help with that, contact me.
Update: Got hold of a Pacman Battle Royale PCB.
A Zero Point (Unico 1998) board came in for repair. The game is mostly working but the graphics are totally screwed up and there's no sound...
There are 2x DIP28 62256 SRAMs near the bottom of the board which are for the foreground and background layer tiles. Piggybacking both RAMs almost
fixed the graphics so I changed out both RAMs....
I tested them later and as expected they were both bad.
Now the foreground and background graphics are good but the sprites have horizontal lines through them....
It's a bit difficult to see in the pic but the bottom of the P should be solid whereas it looks partially transparent now showing the green
background through the P. The horizontal lines likely means some logic is bad because horizontal lines through sprites is unusual. The
normal fault is vertical lines which means a sprite ROM related fault or logic connected to the sprite ROMs. I probed around and piggybacked
a few chips and the only chip that affected the horizontal lines on the sprites was a 74LS374 at the top of the board near a bank of
SRAMs....
But piggybacking all of those chips (including the RAMs) did nothing. The bank of 6116 SRAMs at the top are for the sprite screen display RAM.
There is another bank of 6116 SRAMs just above PAL 09 (check the larger board pic at the top for that PAL location) and those are sprite tile
generator RAMs. If the sprites are scrambled then those RAMs could be bad. In this case the sprites look ok just with lines through
them so it has to be related to the bank of SRAMs at the top. Probing those RAMs showed the top two RAMs had a nasty/dirty sounding signal
on pin 22 (both RAMs are tied together). The datasheet shows that pin is A9. I traced the pin and it was tied to pin 11 of a nearby
74LS161..... GS-branded (Goldstar crap!). I noticed that the same signal was also on the same chip on pin 10! I checked the
resistance between pin 10 and pin 11 and it was around 3.7 ohms. It looks like the two pins are shorted together. I pulled the chip and it
tested bad on pin 11 (stuck low) so I replaced it :-)
To my surprise it didn't change anything and the fault remained! At this stage I can't trust any of the shitty Goldstar chips so I pulled
and replaced the remaining 5x 74LS161 chips. One of the 161 chips tested bad on pin 13 but all chips were replaced. Never put GS chips back
on a board even if they test good!
So with the sprite problem fixed it's time to look at the sound. There is a LM324 op amp chip located near the audio capacitors. Probing the
4 outer pins (1, 7, 8, 14) gave some audio on my logic probe piezo speaker. This means the sound is working correctly. Touching a wet finger
to the pins on the main power amp IC did not make any pop sounds. I checked the main power amp and it was burning hot so it's probably
blown. This is an unusual amp type and I didn't have a spare in stock (SEC KA22065 with PCB silkscreen KIA8207 which is likely a compatible
part). I removed the amp IC and underneath there were alternative holes silkscreened 1241. This is likely to be a NEC uPC1241H amp IC which
I had plenty of spares in stock. I soldered a new one into the board and that fixed the sound :-)
21st February 2024
A Sega Golden Axe board came in for repair from a local friend....
The game is working but the colors are screwed up. The test mode CRT check shows it better VS MAME....
The graphics look ok so the issue appears to be at the final output color mixing stage. Let's check the schematics...
This page shows the RGB output section. The way to diagnose this is to find the RGB outputs and trace backwards, checking each part until
something bad is found. There's not a lot going on here. The outputs connect through a resistor DAC, then to 2x 74HC273 logic chips, then to
the color RAM then to 2x 74LS245 logic chips that connect to the main program data bus (which is working fine). I have previously gone into
the test mode and run the memory test and all RAMs pass so it's not the color RAM. These boards are a bit annoying because the ROM board has
to be on top to test it so it's difficult to probe stuff while the power is on so I just skipped all of that. I piggybacked the 2x 74HC273
chips and powered on and it almost fixed the issue so I removed them and swapped in some new 74HCT273 chips. The original chips are branded
NEC and both tested bad with some outputs stuck which is not unusual but interesting in this case as both are bad and these are the only NEC
chips on the board. Maybe a bad batch of chips so something to watch out for in future when repairing System 16 boards....
I re-tested the board and everything is good....
9th February 2024
While I'm playing with Midway Y-Unit hardware I decided to attempt the resurrection of a dead Smash TV board that was in really bad
condition. Looks to have been left outside in a damp shed which (like usual) probably happened after the board stopped working....
Basically every socket is rusted and the legs of all the socketed chips are rusted.
The really funny thing is I've probably seen it before, about 23 years ago. This board was likely to have been present and sold while I was
working part time (between 1999-2005) at Filtek Australia because there's a card attached to the board...
Well actually I wouldn't say 'working'. It was more like playing with stuff and getting access to anything I could lay my hands on and
dumping it, and occasionally fixing some stuff. A lot of the arcade games in MAME came from boards I dumped at this same place from the
massive pile of crap they had stored over the years. After years on a long journey with an abusive nasty old mean and clueless owner it has
finally returned to its rightful home LOL!
I first removed all the socketed chips and washed the board in the sink using a small paintbrush to scrub off the dirt then I rinsed it with
clean water and left the board outside to dry in the sun for a few hours....
The result was a spectacular transformation from a piece of crap into an actual good looking arcade board. I removed and replaced
several sockets, cleaned the chips with fine sandpaper then plugged in the chips and I was surprised to see that it works hehe!!
Wow talk about lucky!! I played a game and some sounds were missing. The title screen has a Smash TV logo that drops down from the top and
makes a boom sound then it slides out to the right and makes a whoosh sound. The whoosh sound was there but the boom sound was missing and
also the power-on self test 'bong' sound was missing. In the test mode when moving up/down on the menu items the 'clang' sound was also
missing. I ran the game in MAME and pressed the tilde (~) key. This brings up a menu that has selections for adjustment of various things
including volume of each sound chip. I reduced the volume of each listed chip to zero until it sounded the same as the real board. It ended
up being the MC1408 DAC. These boards are all very simple and are actually the very same sound board used on Williams System 11B/C pinball
games with what appears to be little or no changes. The sound at power-on is the same classic 'bong' sound heard when powering on all Williams and
Bally pinball machines from around 1989 onwards. This is the board I have that came with the Smash TV main board....
The board number is 5766-12130-00 REV. - D
I have another sound board here from a High Impact. It's nearly identical....
This is board number 5766-12702-00 REV. B
I swapped that over together with the ROMs. I first had to replace the amp IC because I had taken both of them when fixing some other games
years ago (pic above shows it after adding the amp IC). I didn't have a TDA2002 but I found one TDA2003. Checking the datasheet shows it's
the same pinout as the TDA2002 with a higher wattage rating so it's compatible. One is enough for testing since the wiring harness only has
one audio volume pot wiring connector plugged in.... these boards need the volume pot connected otherwise there's no sound at all (same as
Mortal Kombat, NBA Jam etc). I soldered the amp IC into the board, powered on and it was opposite.... the power-on bong and title screen
bang sounds were present but the whoosh sound was missing. I checked the board. It looks clean but the axial electrolytic cap at C11 is
missing! The schematic shows C11 is connected to the C1-55536 IC on pin 3 which is the output pin so the whoosh sound is generated by that
chip. The only other visible changes are the ROM sockets which have 32 pins to allow for larger ROMs but the original Smash TV 27C512 EPROMs work
fine (note the orientation and position!). Some of the white jumpers are also in slightly different positions but nothing needs to be
changed. I found another new cap and soldered that in and the sound board works perfect! I could just leave it there but I want to know what
chip is causing the fault on the other board. There's a fairly easy way to check all the sound amplification-related chips and find the bad
chip. With a wet finger simply touch the bottom pins on the MC1408, C1-55536, 1458 (x4) and the YM3012 (and if all sound is missing also
touch the TDA2002 main power amp). A faint pop sound should be heard. I got the pop sound on all chips except the MC1408. This chip requires
negative voltage on pin 3. It measured -5V so that was ok. The output on this chip is pin 4. I had previously measured the voltage on that
pin on the working board and it was around -0.637V and drops slightly when audio is playing. On the suspected faulty chip the voltage was
around -0.78V and didn't move when audio was playing. I swapped out the MC1408 taken from the working board...
I powered on and I heard the bong sound and figured it was fixed. But after about 30 seconds I heard the bong sound again. It continued to
repeat about every 30 seconds! Maybe I screwed something up somewhere or maybe something else has gone bad. It seems like the board is
resetting. I checked the reset pin on the 68B09E (pin 37) and sure enough it went low then high just before the bong sound, meaning it's
watch-dogging. I need to check where the reset comes from on this board. Unfortunately there are no Midway Y-Unit manuals with
readable sound board schematics. Since this board is used on Williams System 11 I googled and found a System 11 schematic which just
happened to be for Banzai Run. The board layout diagram shows the part number as "5766-12130-00 Bare P.C. Board". So this is a perfect match
for my board. Niiiiice! The part number on the schematic is "D-11581". The schematic is 100% readable. Many years ago when working at Filtek
I scanned a LOT of pinball manuals (probably over 100 including a near-full set of Gottlieb manuals ^_^) and Banzai Run was one of them so
this might actually be one of my schematics. I'm pretty sure it is because it's a 600DPI greyscale scan and that's the same settings I use
hehe!
Anyway, the schematic shows the reset comes from the main board on pin 18 of the data connector J4. That means the main board can't 'see'
the sound board. The bong sound is automatically generated by the sound board only so that explains why that sound is heard and no other
sounds are generated. I was just about to go in deeper and look for the cause when I noticed the red stripe on the flat data cable didn't
line up with pin 1 marked on the board. OOPS!!! I quickly swapped the cable around before anyone noticed LOL!
Ok I'm dumb. So with the cable around the right way everything is working perfect. So the only thing I found bad on this game was the MC1408
DAC on the sound board? That's weird! It looks like this board was fully working and just abandoned at some point in the past by the
previous owner and was actually working fine until it got wet LOL! Not to worry, now it's in good hands and I will take good care of it :-)
A bit later I was checking the game in MAME and I noticed something. While doing the sound board repair I have been going into the sound
test to check it so I'm very familiar with how it looks. In MAME in the sound board test a screen shows with some text "SOUND BOARD TEST".
Comparing that with the real board shows....
It's different!!! WOW!! The real hardware shows additional text with the name of the sound that is being played. Could this be a bug in
MAME? I checked all the versions and none of them show the sound names. So yeah looks like I found a bug with MAME vs the real board and for
20+ years no-one noticed it hehe!
While playing the game I came across another weird thing. The real cab uses two joysticks with firing on the 2nd joystick so firing opposite
directions simultaneously is impossible since it's a joystick. However with the real board plugged into any JAMMA cab the firing
up/down/left maps to buttons 1-3. While playing I accidentally pressed buttons 1 and 2 together.... that's an impossible up and down firing.
The screen blanked out grey and eventually reset itself back to the title screen. I tried it again and this time when the screen was grey I
pressed the on-board reset button. A screen showed and I had a WTF moment hehe! I googled and found by pressing reset while in a game it
activates the cheat warp #3 stage skip.
It's documented on the net, search "WARP #3 ACTIVATED = SECRET KEY".
You can trigger it in MAME simply by starting a game, wait until the enemies start coming at you then press F3. The game checks something in
the NVRAM and sees it's an in-game crash so gives the player a skip and bonuses then continues from the next level. However in an arcade
that would never happen since the PCB reset button isn't accessible so this cheat will never happen in operation. The game will simply reset
after about 5 seconds back to the title screen. It also seems to remember it happened and doesn't crash again even when multiple fire
buttons are pressed together at the same time. Since holding buttons 1 & 2 (fire up + fire down) doesn't crash the game in MAME and the
screen doesn't blank out it means that something isn't emulated correctly. So that's another thing that no one noticed for 20+ years ;-)
Another FYI thing, I tested out trying to convert any of these Y-Unit boards to a different game. Unfortunately it's not possible. I
discovered that there are several revisions of the main boards. Normally it would not be a major issue but the revisions are located around
the various game-specific PLD (i.e. protection) chips. As well as that there are some additional wire mods on the bottom of some of the
boards. I suspect that the PLDs that are game specific have been programmed based on those game-specific board revisions and wire mods. This
means swapping in a different game is nearly impossible unless the board modifications are studied in detail and documented for EACH game
and EACH board revision. Basically it's too much work so it's not going to happen. So if you are going to try to replace a board with one
that is damaged and unrepairable be sure you replace it with exactly the same board revision and apply the same wire mods otherwise it's not
going to work. In my case I was trying to get Mortal Kombat working on a High Impact board. The best I could get was I had the game
working but all of the 8Mbit mask ROMs tested bad on the power-on test. In-game graphics were scrambled and there was no way to know exactly
what was causing it despite adjusting some of the wire mods to suit the traces on my working Mortal Kombat board (which actually had no wire
mods). So be kind to your boards and don't leave them in a leaky shed for ~20 years and if you are lucky they will stay working for many
years.
February 3rd 2024
After repairing the previous Mortal Kombat I figured I could try to fix a totally dead Mortal Kombat board I've had lying around for
possibly 10-15+ years. Now that I have a working board for reference I was hoping it could be helpful for repairing my board. It's not
totally dead-dead, it shows the start-up 'rug' pattern but it looks very strange and then the screen goes black. This looks like a
protection check failure. I swapped over all of the socketed chips. To my surprise it came up....
Wow it's mostly working!! After pressing any button the game screen came up and the game is running with huge graphical issues....
I swapped back the chips one by one and eventually found the bad chip. Unfortunately it was the 40 pin protection chip
"5346-40025-8".
I looked through my boxes of random old chips and found another similar chip without a label. This was an Altera EP910
whereas the original chip was an Intel P5C090-50. These two chips are compatible. I swapped in the chip and powered on and got the
same test error screen so it looks like the chip is good. That was super lucky!
I will keep the bad chip for test and practice purposes for a future decapping effort. The chips are EPROM-based with a separate protection
fuse, very similar to an i8751 MCU so deprotecting these and dumping them might be similar.... decap, mask off the EPROM with paint (except the
protection bit area), UV erase it and then read out the EPROM. We need to get hold of all of those protection chips on Midway Y-Unit boards
because they are at risk and need to be decapped so they can be re-programmed to a new chip for repair purposes (and to improve emulation)
otherwise when they die it's game over permanently.
Getting back to the repair, now to fix the other errors. The red chips are RAMs. They are a very strange type of multiport RAM with a parallel access mode and a serial
access mode. The exact chip on this board is V53C261 which I previously had not seen.
Here's a list of compatible RAMs that can be used on these Midway Y-Unit boards....
Hitachi HM53461
Fujitsu MB81461
Texas Instruments TMS4461
Micron MT42C4064
NEC uPD41264
Vitelic V53C261
I swapped the 3 bad RAM chips for known good chips and that fully fixed the main board. I plugged in the Mortal Kombat sound board
I repaired back in October 2022 and everything works perfect so that's another board rescued from the junk pile :-D
28th January 2024
A couple of boards came in for repair....
Mortal Kombat
The game works but colors are messed up. The obvious place to start is the color RAMs which are located at U5 and U23. I piggybacked U5 and this showed on screen....
Look like the RAM at U5 is bad. Nothing showed up as bad before because Midway used red text for the errors. They should have used a color
that wasn't red, green or blue so that error text always shows heh! Anyway, I swapped it with a good chip and that fixed the
problem.
Blood Bros.
The game works but the music is missing. To diagnose this I first scoped the YM3014 DAC on pin 2. This is the analog output. There was activity on the scope so the DAC appears to be working. The issue is going to be the HB-41 hybrid module. To test that I bypassed it by jumpering pin 2 of the DAC directly to the main audio amp....
The music was audible, but obviously it's going to be distorted because the signal level is wrong (too hot), but this proves the digital
audio section is working correctly. Checking the pinout on my HB-41 schematic
(available on my Reverse Engineering Page) shows the audio from the DAC goes into pin 17 of the
HB-41, through an op amp, out on pin 16 of the module to the PCB and back into the HB-41 on pin 5. I jumpered a wire from module pin 17 to pin 5
(or DAC pin 2 to module pin 5) and music was also audible and even didn't have any distortion heh! This proves the 1st op amp on the HB-41 is bad, and of course I already knew that
because that's the part that most often fails on the HB-41 ;-)
The quick fix is to simply jump a wire from the module pin 17 to pin 5 and that should be more than good enough to fix it. It depends on
which part of the 1st op amp fails. For this particular module half of the 1st op amp was ok (OKI M6295 sound effects) and only the music
was missing, but it might require joining module pins 13 and 16 together if the whole 1st op amp was dead (I need more dead boards/modules
to experiment with hehe!). In my case I replaced the module with my re-production HB-41 and that fixed it :-)
26th January 2024
A few weeks ago when repairing several Space Invaders boards I mentioned the L-board I have would be a good candidate to reproduce. That has
now been completed. As per my usual stance on these things the board is 100% 1:1 identical to the original without any signs of being a
reproduction, although obviously it looks new so can't be mistaken for an original board ;-)
The trace layout was initially based on an original Midway PCB schematic and a scan of the board was used as a guide to trace over the
copper. PCB softwares are very good now and have lots of ways to verify things. The schematic and PCB trace layout are synced, and with the
additional PCB scan as reference I quickly discovered that the actual PCB had several changes vs the schematic. So I updated the schematic
to match the PCB. That means now there's a proper Midway Space Invaders schematic that matches the real PCB for the version using 8x 74LS151
chips for the shifter circuit. All parts are common off-the-shelf parts so it's 100% fixable no matter what happens :-)
The PCB image is very large (approximately 11MP) so view it full size and browse around to see the detail :-)
I might do some minor cosmetic tweaks to this just for my own satisfaction but as-is currently this can be considered 99.99999% complete.
Obviously I can not actually test the PCB yet since it hasn't been made but the gerber files will be made available here soon (most likely
in the next post) if you want to play with it yourself :-)
The schematic will be held for a few more days until I triple verify PCB vs schematic just in case I missed something non-obvious, but then
it will be made available. Update - Schematic is verified 100% and schematic pic/link above is active. Hopefully someone familiar with MAME and discrete circuits can fix MAME's terrible Midway Space Invaders sound
for the fire circuit which currently sounds like it might do when squeezing a duck's nuts hehe!
10th January 2024
A couple of items arrived for dumping....
- Black Rose Rapid Fire Grand Prix QLD (Konami Endeavour). The EPROMs were already dumped
and in MAME. The flash ROMs are now dumped and should be added to MAME soon.
- Aristocrat MK7 main board. The BIOS EEPROM can be dumped but this is basically useless and
will never work in MAME since it uses an Intel Celeron M 440 (launched 2006, SL9LF, 1.86GHz / 1M / 533),
Intel 82945GME Graphics/Memory Controller and a bunch of protection chips including a SIM
card slot and Altera Cyclone II FPGA. In the PCIe-x16 slot was a dual DVI card with a couple of Silicon Image
SiL1364ACNU chips but no dumpable parts. The video is generated by the Intel SLA9H Video
Controller and sent to the DVI outputs via the PCIe-x16 card.
Update: Here's a couple of screenshots from MAME thanks to quick work by Osso....
The remaining undumped Konami Endeavour games are Russian releases and unlikely to be dumped so
this is probably the last Endeavour game that will be dumped by me unless some other
Australian versions are found. Additionally, no one seems interested or has 10 minutes to fix the last
remaining issue of getting past the cabinet door switches so all Konami Endeavour games
are still unplayable :-/
For previous news back to and including 2015 check the top menu 'Old News' link.
You can find a mirror of older offline news on the Wayback Machine. Probably ;-)
<-- Please Donate :-)
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.....it's sleuthin' time!
