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.
