Sep 262018
 

Received from Germany this mint Liquid Kids PCB (on Taito F2 hardware) for repair:

Board was working fine except for sprites, they had jailbars through:

First of all I dumped the two 4Mbit MASK ROMS which store sprites data, they turned out to be good.This part of graphics is almost entirely generated by a custom ASIC marked ‘TC0200OBJ’ which showed some sign of previous rework on my board :

We can see pinout and implementation of this custom in the Final Blow schematics :

Probing with a scope its outputs data pins revealed some unhealthy signals (shown on the right on the below snapshot, good on the left)

I decided to remove and replace the ASIC:

Soldered the spare :

The jailbars were gone.Job done.

 Posted by at 11:21 pm