X-Men (Konami) PCB repair

Recently I've been sent an original Konami PCB for repair.The board was not in mint condition, it was heavily reworked, a lot of ICs (RAMs, ROMs, TTLs) were socketed and replaced.

Board was marked as working but with missing sprites, that was indeed what I got when I powered it up :

I entered in TEST MODE and performed a MASK ROM check which reported all the sprites devices as not good :

Object are handled by two custom ASICs (in QFP120 package) that work as pair, the '053246A'  (which generates the addresses to the MASK ROMs) and the '053247A' (which draws the sprites) :

Looking at schematics made by 'jotego' from MiSTer (thanks to him!) I checked the connections between these custom ICs and the rest of the board, everything was correct.But when I went to probe the '053247A' I found some stuck outputs :

These are the color and priority bits sent to the '053251' (the priority control custom IC) :

The '053247A' was most likely faulty so I decided to replace it, luckily I had a donor board to take the part from. 

Desodered the defective part with hot air :

Installed the spare :

The sprites came back :

Another successful repair.

Namco 'CUS120' reproduction

A couple of years ago I donated 'furrtek' a Namco 'CUS120' custom IC.This part is found on System 1 hardware (Pac-Mania, Splatterhouse, Dragon Spirit, Galaga '88 to name few games that run on this arcade system) and comes in a QFP64 package :

This custom IC a sprite/tilemap mixer and also generates addresses to the three palette RAMs :

After some time 'furrtek' decapped the chip and imaged the die extracting its logics and drawing schematics .

He designed also a replacement and sent a sample to 'frsj8112' for testing.Unfortunately there was some issue :

The project was stalled for some time until 'Apocalypse' took care of it.At that time I designed a replacement too :

I did testing of the code prepared by him (the replacement is powered by a programmed CPLD).After some attempts he pinpointed where the problem lied and sent me a new code that worked perfectly.Here's testing on Splatterhouse and Pac-Mania PCBs :

Once again a huge thanks to 'furrtek' for his invaluable work (chip decapping, die tracing and schematics drawing) and to Apocalypse for his troubleshooting and fix.

'FLIP-FLOP' - a Sharp X68000 FDD emulator

This was an old project I was working on from time to time but never had the chance to finalize due to different reasons.Now finally I came to a final revision of my Sharp X68000 floppy disk drive emulator.

For the uninitiated the X68000 is a home computer created by Sharp Corporation. It was first released in 1987 and sold only in Japan.This machine is quite popular among videogame enthusiasts since it reproduces arcade experiences like no other home machine (it was used, indeed, by Capcom as development platform of many games)

Many different designs of 'FLIP-FLOP' X68000 FDD emulator have been done since the time of a rough prototyping (which worked pretty good)

This is the final revision of the emulator board :

'FLIP-FLOP' connects to external FDD connector of X68000 and emulates one single drive at once.For now it can be plugged only to tower and PRO models of X68000 but Compact models will be supported later, too

Night Slashers repair log

 Got an almost mint Night Slashers PCB for repair:

For the uninitiated Night Slashers is a horror-themed beat 'em up game developed and published by Data East in 1993.

Hardware overview :

Main CPU : ARM (@ 7.0805 Mhz), Zilog Z80 (@ 3.58 Mhz)
Sound Chips : Yamaha YM2151 (@ 2.01375 Mhz), OKI6295 (@ 7.627 Khz), OKI6295 (@ 15.255 Khz)

 

As usual, I did a visual inspection and found two missing 'RCDM-I1' custom resistor arrays (used for inputs) :

I replaced them with reproductions of mine :

As said, the board was in very good condition but it displayed only a static garbage screen on boot:

The main CPU is a Deco processor (156 - encrypted ARM) whose pinout is unknown, anyway I was able to locate the WORK RAMs (four 32K x 8-bit Sharp LH52250AN-70L)

Probing the data lines of them revealed some stuck signals.I decided to replace them all with new ones (bought on eBay) :

The board finally booted into game but the screen was all covered by garbage graphics :

There are a couple of surface mounted custom ICs that handle playfields graphics, they are marked '74' and '141' :

The soldering oof the '141' was suspicious to me :

  So I did a reflow and this fixed the issue :

I played a game and no other problems were found so the board was 100% working again.Another repair accomplished.

Mystic Warriors repair log

Got a mint Mystic Warriors PCB for repair (an action game released by KONAMI in 1993) :

On power up the POST reported many bad devices :

 

In the details the devices @5F-3F-5D-7D-6B represented almost the whole sound system :

• 5F = first '054539' PCM 8 Channel custom chip
• 3F = 32K x 8-bit SRAM
• 5D = second '054539' PCM 8 Channel custom chip
• 7D = 8K x 8-bit SRAM
• 6B = Z80 ROM (27C010)
  

  The sound system is ruled by a Z80 CPU (Z80E in this case)

When I went to probe it I found all the outputs (address and system control lines) were silent, this could be a sign the CPU is internally faulty hence I desoldered it :

I tested the CPU on another board and I had confirm it was really fauty so I replaced it :

 

With a good CPU the board passed the initial test but the screen was yellow tinted :

A yellowish screen means the blue color is missing.The signal is generated by one of the three '054573' custom SIL (one for each RGB color), the one @U50 :

Tested the output with a logic probe revealed a stuck signal :

 I removed and replaced the component with a reproduction of mine :

This fixed the lack of blue color and board completely.Another repair accomplished.

Demon's World repair log #3

Recently I received for repair this Demon's World PCB (a platform game released by Toaplan in 1989,  known also as Horror Story)

The owner told me that the board originally was missing the chip marked 'GXC-04' so he bought the replacement I designed time ago :

 You can read more about this custom chip and my replacement here :

Toaplan 'GXC-0x' reproduction

But, even with the replacement fitted, the board was not working so he decided to send it to me to have a look.Indeed the board was not booting, only a raster of wavy lines on the screen at power-up :

As usual I did a visual inspection of the board and found a deep scratch on component side :

Testing the continuity with a multimeter revealed four broken traces, I promptly patched them with some AWG30 wire :

This made the board booting up finally :

The game was fully playable with sound but sprites were corrupted :

Sprites data are stored in four 28 pin 1Mbit MASK ROMs :

 

I dumped them and one device turned to be empty :

This was a clear sign it was bad and needed to be replaced.In place of of these 28 pin 1Mbit MASK ROMs you can use non-JDEC 32 pin 1Mbit EPROMs (like 27C1000, 27C301 and other).The PCB is already set up to accept 32 pin EPROM as you can see from below picture  :

 So it was only matter to install a bigger socket and program a proper EPROM (Hitachi 27C301 in my case).This is what I made :

This fixed the sprites issue :

 No other issue found so board 100% working again.Another successful repair.