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Guru's Reverse-Engineering Page

Guru's Reverse-Engineered Parts Page

Here you will find some schematics for parts that I reverse-engineered. Most of these were reversed many years ago and are shown on the repair logs on this site but now they are all in one place on this page to make them easy to find. A few were updated/cleaned-up recently just for this page.

I don't have time to reverse everything. These parts are just parts I needed to reverse for my own repairs.
But if you have something and you want it reversed you could send it to me and I will reverse it and make the information available here for everyone.... unlike other scumbags who take info done by others, make reproductions while telling people on forums they will share the info but actually keep everything secret and share nothing (LOL!) and then they milk the retro-gaming community at both ends with very expensive prices for PCBs that cost just a dollar or two to make LOL!

Given this info below, it wouldn't be difficult to use open-source software like Kicad to make a replacement PCB, but most of these can actually be fixed with very little effort. A lot of them fail because of a shorted SMD cap. To fix it, use hot air to soften the coating then scratch away the black coating where the big lumps are (those are the caps ;-)
Then hot air the part and remove it with tweezers then replace it by hand soldering a good part in the same place.
Problem solved ^_^

I rarely keep stock of any (I normally just fix the original part) but if you see a photo of the actual PCB I re-made then I might have some stock... you can try your luck and ask ^_^

# Description Schematic Images
001 Konami 054986A
Audio module used on several Konami arcade PCBs including Lethal Enforcers, GI Joe, Violent Storm, etc
First schematic was done in 2017. Second schematic was done in 2022 and has more detail.
Konami 054986A Schematic
Konami 054986A schematic done later with more info
Konami 054986A
002 Konami 005273
Custom resistor array used on almost all 80's and 90's Konami arcade PCBs for the inputs
Konami 005273 Schematic
Konami 005273 resistor array
003 Taito 48CR-1
Custom resistor array used on several Taito arcade PCBs for the inputs
Taito 48CR-1 Schematic
Taito 48CR-1
004 Seibu HB41
Audio module used on several Seibu/TAD arcade PCBs including Cabal, Raiden, Toki, Blood Bros and some other non-Seibu games such as Operation Wolf. The actual cost to make this was about $6.00
The part that usually fails is the 8 pin chip. This was tested and worked perfect first time. The pic to the right is the first one I built using parts salvaged from a faulty original module. The part sizes were larger than the proto module design (rev A) so I had to squeeze them in. The board has since been updated to use parts that are the same size as the original so parts can be salvaged from a faulty module. The cost to build this is about $3-$6 depending on where you get the tantalum caps from. The tantalum caps are the most expensive part and if you salvage them from the old module it will reduce the cost by 50%.
The module was built and tested on a Blood Bros PCB and works perfect :-D

The schematic (with extra repair info) and board was also updated and posted here (Rev. B, Jan 2024).
Seibu HB41 Schematic
Seibu HB41
Seibu HB41 (rev B)
Seibu HB41 - Guru Version A Prototype
005 Seibu HB45A
Audio module used on some Seibu arcade PCBs including Raiden II and *some* versions of Zero Team and Raiden DX. The actual cost to make this was about $6.00 and most of that cost was the tantalum capacitors.
This was originally reversed by 'Pacman70' (old schematic shown to the right, with corrections) and was immediately targeted by the usual 'perp' as useless and incomplete. You can read it here (mirrored locally). This is quite funny.
- Firstly the voltage on the module is completely irrelevant. The input power comes from the main board where this module is plugged in. It is of course +12V on pin 9 of the module so any voltage on the schematic doesn't affect it.
- Secondly, the comment says there's no voltage on pin 8 of the NJM4560 op amp (it's just a LM358) and the 2x 2.2uF caps. Erm, they are *clearly* connected to pin 9 of the module so they are automatically connected to the power.
- Thirdly, the comment says the resistors under the NJM2060 op amp (it's just a LM324) are missing. I suggest you get your eyes checked buddy, they are there at R4, R5, R6, R10 & R11 LOL!!!!
So this proves the 'perp' didn't reverse it because if he did he would have known all of that and a lot more. He either paid someone to do it or a different person did the reversing and he just ripped it off LOL! I suggest next time someone posts a schematic for something you just keep your big mouth shut LOL!
I reversed a module I have here and checked everything. Once the parts are removed it's actually not that complicated. I scanned the board and quickly cleaned it up in Photoshop and used that for verification when routing it. I found the only mistake on the other schematic was C6 value is missing (it's 10nF) and C5 is supposed to be wired to pin 12 of the op amp not to the center of the 2x 33k resistors. All things considered, the original published reversed schematic was a pretty good effort. Remember anything published is better than hoarding everything and publishing nothing like the 'perp' does LOL!

Of course I re-reversed everything the 'Guru way' so the schematic is now perfect and better than everything before it hehe! The footprint of the op amps covers both the 150mil and 200mil versions and the rest of the design mirrors the original (i.e. no vias). This is effectively a 1:1 identical copy but using modern technology so it is repairable now. The cost to build this is about $3-$6 depending on where you get the tantalum caps from. The tantalum caps are the most expensive part and if you salvage them from the old module it will reduce the cost by 50%.
The module was built and tested on a Raiden II PCB and works perfect :-D
Seibu HB45 Schematic
New Guru Schematic

old HB45A schematic by 'Pacman71'
old schematic
Seibu HB45A
Seibu HB45A
Seibu HB45A
Seibu HB45A
Seibu HB45A
Seibu HB45A
Seibu HB45A
006 Taito TC0070RGB
15-bit RGB DAC used on several Taito arcade PCBs including Chase HQ, SCI: Special Criminal Investigation, Operation Thunderbolt, Cadash, Ninja Warriors, Darius and many others. The legs often break off these or they get snapped in half by careless losers so it's better to just replace it with a proper solid PCB version. The actual cost to make this was about $5
Taito TC0070RGB Schematic
Taito TC0070RGB

Taito TC0070RGB Taito TC0070RGB
007 DECO CPU-7
Custom potted CPU module used on a few Data East games such as Burger Time and Zoar
DECO CPU-7 Schematic
008 DD1718PA Boost Module
Small module used to get higher voltages from a lower input voltage. This will output positive AND negative voltage. Simply change R1 to get a different output voltage.
DD1718PA Boost Module Schematic
DD1718PA Boost Module Schematic DD1718PA Boost Module Schematic
009 IGS PGM Cave bootleg cart
Full schematic for a simple IGS PGM board-set you can make that plays 3 Cave bullet-hell shoot'em-ups.... Espgaluda, Ketsui and Do Donpachi Dai-Ou-Jou.
IGS PGM Cave Hack Boards Schematic IGS PGM Cave Hack Boards Schematic
IGS PGM Cave Hack Boards IGS PGM Cave Hack Boards
010 Full schematic for a Sega SC3000 multi-cart with 4MB capacity. This holds basically every SG1000 and SC3000 game ever made.
Sega SC-3000 Multi-Game Schematic
Sega SC-3000 Multi-Game
011 Full schematic for Namco System 23 main board. This is an 8-layer board. This took around 12 hours per day full time for 8 weeks to reverse. As well as showing all the connections, all clock signals on all chips across the entire board have been measured and noted on the schematic and brief descriptions of what all the custom chips are doing, as well as some chip-related repair infos. The schematic is a single sheet approximately 2 meters square. To give you an idea how big this is, the NAMCO SYSTEM 23 text at the top is 100mm high. Yes, really. This is a preview. The actual pdf schematic is not publicly available to avoid complaints from people creaming their pants when they see it ;-)
Namco System 23 Schematic
Namco System 23 PCB
012 Taito Cadash RS-422/RS-485 Communication Schematic.
Cadash is one of the few 80's games that has basic networking built in. It can be hooked up to another Cadash board for 2 player gaming. This schematic shows how the MCU is hooked up and the wiring of the inter-connect cable.
Taito Cadash Serial Communication Schematic
013 COSMO by TDS & Mints FULL Schematic.
This game runs on Taito 3-board color Space Invaders hardware with a custom top board added. I don't recall how long this took to reverse and draw but it was at least a few weeks. This includes the special top board schematic including documenting the 8 connectors and where the 50+ wires are joined to on the main boards, as well as full schematics of all the specific Taito PCBs used on this game.
This is a preview jpg. The actual 'readable' pdf will be released later after the game is fully working in MAME. I suggest one of the known developers with many years of experience with TTL logic figures out the emulation, fixes it and more of these special schematics may be done for other games to improve the emulation.
A video of me playing the game can be seen on my youtube channel here.
COSMO Schematic
014 Atari 2600+ cart #1
Full schematic for a simple Atari 2600 cart that can select up to 16x 4kB (FIXED SIZE 4kB ONLY) ROMs using a (ghetto) 4-position DIP switch. This is a reverse of the 10-in-1 pack-in cart that comes with the A2600+. It uses a single SST39VF512 (64kB x 8-bit) TSOP32 flash ROM with only 40kB used and the remaining 24k blank (00-filled). This isn't particularly exciting and obviously we can do MUCH better with almost no effort! See the next item for something very similar but far more useful ;-)
Atari 2600 Cart Schematic
Atari 2600 Cart

Atari 2600 Cart
015 Atari 2600+ cart #2
Full schematic for a simple yet much more useful Atari 2600 cart that can select up to 256x 4kB ROMs using 2x 16-position hexadecimal rotary switches. This rotary switch is what should have been shipped with the A2600+. It uses a single 16M-bit (2MB) TSOP48 flash ROM. 256 x 4kB = 1MB but I have plenty of 29F016 flash ROMs in stock so that's what I'm using. Since the ROM is pre-selected this cart will work with the A2600+ unlike most other multi-carts that don't work because the 2600+ is a ROM dumper and tries to dump the ROM then run it from local RAM.
Atari 2600 Cart New Guru Design Schematic
Atari 2600 Cart, New Guru Design

Atari 2600 Cart, New Guru Design
actual PCB produced
016 Atari 2600+ cart #3
A nice Atari 2600+ multi-cart that uses a RPi pico to defeat Atari's non-support of multi-carts lol. The pico emulates a 4k, 8k, 16k or 32k ROM and the switches allow hard selection of a bank that the A2600+ can't detect so it just loads the ROM thinking it's a standard cart with the pico seamlessly taking care of bankswitching. This is a work-in-progress with my usual hex rotary switches added and also using proper level shifter chips. Additionally a 74HC165 is hooked up to read the switches using only 4 GPIO pins. Previously 4 GPIO pins were being used to read a 4-position DIP switch resulting in a maximum of 16 games selectable. Now with 2 rotary switches the maximum selection is 256 :-D
This will need code changes to make it work with the 165 but it seems the guy who was doing the original project coding has dropped off the side of the planet like a lot of random people do :-/
If I ever get this working I'll post full schematic and gerbers but at this stage it's a non-working prototype preview.
Atari 2600 pico Cart, New Guru Design

017 The Simpsons Video Schematic (THE MISSING PAGES)

These are the missing video section schematic pages (2) for Konami's The Simpsons arcade PCB. It is drawn using the same Konami style from 1991 so that it blends seamlessly with the existing partial schematic to make it complete. It also includes the same logo/title block, sheet border, signal names and across-sheet signal references. 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 in real life, as squares and with in-order pin numbers. Print onto a single sheet of A3 paper (use both sides) and insert into your original Simpsons manual for completeness. The schematic is large so zoom in to at least 300% to read it.
As for repairs, aside from all the nasty Fujitsu logic chips used on these boards that fail, note the most common custom chips failures are a bad 053247 (sprites) or a bad 051962 (backgrounds). These customs contain internal RAM and if you know anything about PCB repairs you will know RAM failure is the most common fault on any PCB. If you have major sprite or background faults use the schematic to check the address and data pins and most likely you will find some dead pins. Of course do that AFTER you have checked/replaced the ROMs/RAMs and connected logic.

There are no plans to update this but if any errors or omissions are found/fixed there will be a note about it and the new version will be posted here.

Initial Release: April 9, 2024.

Update (1) May 20, 2024 - Increased text sizes to match the original when printed at the intended A3 size.
The Simpsons Video Schematic (THE MISSING PAGES)
018 UnoCart with serial header

This is a normal Atari 2600 UnoCart (multi-cart using STM32F407VGT6 MCU) with the serial pins brought out to a header and the BOOT0/BOOT1 pins as jumpers to enable the bootloader for serial programming mode. The original design has open-source firmware but for some very strange reason the developer never released an official PCB design/gerbers even though he did produce a small PCB that fits inside an original Atari 2600 cart shell shown at the top of the official manual LOL! Instead he told people to use a ST Discovery board and a silly breakout board he made available. That was of course, a mistake LOL! So then a bunch of people figured it out, copied it and made their own PCB and started selling the UnoCart but only with the SWD programming pins available (most likely because they didn't fully understand the STM32, thus requiring a proprietary STLINK/V2 programmer) and skipping several other programming methods built into the bootloader. Finally now we have something that can be programmed exactly like the Gotek Flash Floppy drive... at a PC/desk using a cheap serial-USB adapter and 4 wires. The Unocart is a cheap alternative to the proprietary, locked up, expensive and not-available Harmony/Melody multi-cart. It can run any cart (except a few homebrews but there's actually no need to use a new bankswitching method as there are already plenty out there that can be used for software development.... think for an extra 30 seconds...) and supports all the common bankswitch methods up to DPC. Pitfall II runs but the sound emulation is not the best with some notes off-pitch and the music speed a bit too fast compared to an original cart, but it's playable. When I set up a compile environment I'll make some tweaks, recompile the firmware and see if I can improve it. Until then it's usable as-is.
The PCB shown to the right has been re-created by me based on a couple of small photos posted by the designer. This is the unreleased small PCB that fits inside a standard Atari 2600 cart shell shown on page 1 in the manual.
This specific Guru version has some changes and enhancements and is very close to Guru-Level perfection. Of course it's also no longer 'unreleased' lol.
I should make this use a smaller STM32 chip as this huge 100 pin chip is rediculous since over half of the pins are not connected. A STM32F410CBU3 in QFN48 package might be the one to use but I have to look into it.... so many projects to fix hehe!
The Simpsons Video Schematic (THE MISSING PAGES)
Unocart 2600 with serial programming header

PCB Gerbers (coming soon)

FW: UnoCart 2600 V18
FW: PlusCart 2600 2.3.17
UnoCart 2600 Manual
019 SIDKick pico

A really nice (almost-open-source) MOS6581 / MOS8580 SID replacement using a (very cheap) Raspberry Pi pico and a carrier/adapter PCB. The design is pretty good but like most hobby projects the board routing needs work. I built one and it works great. The problem is, as-supplied, it falls into the same category as the original... it will fail eventually and won't be available in the far future due to not being fully open-source. While the firmware is 'mostly' open the hardware info is hoarded like usual. Now it's a couple of steps closer to being open-source ;-)
With the official fully open RPi Pico Schematic and this info it could be possible to make an all-in-one custom DIP28 Pi+SIDKick board. Maybe by removing the level shifters and replacing them with 1k resistors as was done on the official A2600+ cart. It's a pity the developer didn't use a STM32. Another commercial SID replacement (ARMSID) uses a STM32F410CBU3 (QFN48 package). The STM32 series has 5V tolerant I/O so the level-shifters could be removed, thus making space for the on-board DAC, or just use a common tiny SOT-package opamp like the commercial SID does. Oh well, back to the old drawing board ;-)

Currently this is a 2nd-pass at the schematic and PCB. The lazy ground copper fill was removed and many traces re-routed and cleaned up. There could be further changes to this later but it's probably at or nearly at 'Guru-Level' perfection now.... at least routing-wise. Really a shame not using a STM32, it could have been perfect. I contacted the developer and he wasn't interested in making a proper version using the STM32 which leaves it wide open for others to fill the void. It wasn't long before someone moved in and it's called KungFu SID. Unfortunately still work-in-progress so not a full replacement right now, but in time it should improve and this will be the default SID replacement to get. Eventually I'll re-do this one with a proper PCB using a smaller QFN package but it's too early since it's not done yet.

The original SIDKick project is here.
SIDKick Schematic
SIDKick Schematic

PCM5102A DAC Module SchematicPCM5102A DAC Schematic
SIDKick pico PCB
020 Pi JAMMA

This is an interface board allowing a RPi 3B or 3B+ to connect to any standard JAMMA arcade cabinet. The software shows some games which can be selected with the joystick and played. The software is a bit janky and needs work but it is usable. The trace routing was also the usual amateur mess. I took the existing janky board and made it better, using more common parts and removing some parts that do nothing. Additionally, the original was using a silly AN7511 mono amp chip that costs $15 LOL! I removed it and used a cheap stereo amp module. For any game that outputs stereo I now get sound out of both left/right cabinet speakers if it is wired for stereo. If there is only 1 speaker it outputs dual mono. Either way, now there's a choice. It also uses a cheap chinese HDMI to VGA converter box to convert the Pi's HDMI video output to RGB so it works with any 15kHz arcade monitor with settings to output standard 31.5kHz VGA to an LCD monitor. There was also many routing changes/clean-ups, removing holes for a bunch of parts that are not populated, fixing the Pi mounting holes to be the *actual* standard and documented spacing 58mm x 49mm and removing a lazy jumper wire (LOL!) and re-routing that trace on the PCB. The updated schematic, BOM and gerbers will be published later after my new version is built and tested.
Schematic/BOM (coming soon)

PCB Gerbers (coming soon)

021 Midway Space Invaders

1:1 *exact* reproduction of the Midway Space Invaders L-board. This is an officially released version that Midway called the cocktail version. It uses an L-board that has all TTL logic and doesn't use the uncommon shifter chips so it can be repaired no matter what the fault is. I suspect Midway were having trouble sourcing those shifter chips and redesigned it to use common logic instead. Lucky for us since that makes it 100% reproducable. Primarily this was made to convert a bunch of junk Midway 8080 games to Space Invaders. But the official schematic has some errors so this schematic fixes them and is 100% accurate to the real PCB. Maybe someone will look at it and fix the bad fire sound in MAME ;-)
Midway Space Invaders
Midway Space Invaders
Midway Space Invaders

PCB Gerbers (coming soon)

022 MB834100 mask ROM to AM27C400 EPROM Adapter

This adapter can be used to replace any MB834100 mask ROM on any PCB. They were common on Taito boards but it will work for any game that requires a mask ROM with the same pinout. You might see scumbags selling these for $$ but if you're smart you'll just make your own adapter for $2.
MB834100 to AM27C400 Adapter
MB834100 to AM27C400 Adapter
MB834100 to AM27C400 Adapter

PCB Gerbers

023 Sound Blaster MCA reproduction

This is a modern reproduction of the Sound Blaster card for IBM Microchannel PCs. I didn't reverse this, I only modified it slightly to make it look more authentic:
- Tidied up the IC location texts
- Removed all the silly b.s. texts and silly logo
- Added a proper Sound Blaster logo
- Added proper board numbers / copyright texts
- Added chip part#'s to all ICs for easier building

This was done for Epictronics and you can watch a Youtube video about it here.

The original project is here (SB1.0 repro) and here (SB MCA repro). These have of course been backed up locally in case they are taken offline ;-)

Sound Blaster MCA reproduction

PCB Gerbers

  More coming soon.....    

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