'NMK-903' reproduction

Thanks to the brilliant job of 'Furrtek' and 'Recreativos Piscis' another custom IC has been reproduced and preserved.

The 'NMK-903' is a small custom IC (in QFP44 package) found on arcade NMK PCBs from the 90s: 

Tracing and schematics of internal structure was done by 'Recreativos Piscis' starting from die shots made by 'Furrtek' who decapped the chip, too :

I designed a proper board (powered by a small CPLD) as replacement of this custom IC using castellated half holes :

The reproduction worked fine at first test :

A big thank again to 'Furrtek' and 'Recreativos Piscis' for their unvaluable work.

Konami '0005291' reproduction

After the last reproduction of the Konami '0005293' I reversed another custom IC from GX400 hardware, the one marked '0005291'.This part comes in an unusual 64 pin quad in-line package (abbreviated as QIP-64 or QIL-64) :

It functions as tilemap generator, here's snippet from Nemesis schematics :

After studying the behaviour of the original custom chip and gathered all info about it found on the net I started my task for create a replacement.This was quite a pretty challenge because I had also to recreate the original QIP footprint.After some time I developed a board powered by a CPLD :

The reproduction worked flawlessly at first shot :

Another step to a full re-engineering of the Konami GX400 hardware, stay tuned for next project.

War of Aero - Project MEIOU repair log

Got for repair this (never seen before) War of Aero PCB, a shooter released by ALLUMER in 1992.

Board was in very good condition :

But it was dead, no sign of life on power up.As first thing I went to check with a logic probe the 68000 CPU (in SDIP64 package) and found the clock input was stuck low :

I traced the clock pin back to a 74HC368 that drives the 16MHz signal generated by the nearby DIP14 oscillator :

Probing the output of the oscillator with a scope confirmed it was dead, no square wave from it :

I promptly removed the part :

And installed a spare :

This brought board back to life :

No other issues found so another board succesfully repaired.

Konami '0005293' reproduction

Another custom IC from Konami GX400 hardware has been reversed.After the '0005292' I reproduced time ago I took into account the '0005293' that can be found always on VIDEO board of this arcade system.  

It shares same SDP64 package :

Technically this custom IC is a priority handler, pinout can be found on Nemesis schematics :

For my task I made use of Salamander bootleg (where this and the other custom ICs have been reversed with the use of 74 series logic gates ) and gathered all info found on the net about the '0005293'.Prototyping was encouraging so I came to this replacement :

After some adjusting of the code and adapting the timing to the hosting hardware the testing of the replacement was successful on my boards :

X-Men (Konami) repair log

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.