Received a Parodius DA! PCB for repair, a shoot’em up and second title in the Parodius Series produced by Konami :
Board booted up and game was fully playable with sound but sprites were wrong:
First of all I launched a MASK ROM check which reported two bad devices @K2 and K8 :
They are, indeed, 4Mbit MASK ROMs that store sprite data processed then by the near ‘053244’ and ‘053245’ custom ASICs :
The result of the check didn’t imply the devices were really bad but also that they could be not reached.So I went to probe them and found that pin 1 of the MASK ROM @K2 was floating while same pin of the one @K8 was active :
Pin 1 is the highest address line of the MASK ROM and should be in common between the two devices whereas, at quick check with a multimeter, it was not.Hence the trace to pin 1 of device @K2 was interrupted somewhere.I added a jumper wire on solder side:
This did the trick, sprites were restored and board 100% working again.Repair accomplished.