At first power up the board booted up into game but I immediately noticed an issue concerning the graphics, all the backgrounds were fashing :
This is a common problem on this kind of board, there are four 64 x 4-bit dynamic RAMs that very often go bad causing screen artifacts:
Probing them with a scope I found the one @IC26 with almost inactive data outputs (good signal on the left of below picture) :
Sure enough I removed the IC :
It failed the out-of-circuit testing :
A new DRAM chip fixed the issue and I was archiving the board as fully repaired but playing some games I noticed the sound was faint even if I set the volume at highest level by acting on potentiometer:
This is a common issue too because this board does use in sound section a little custom IC (in SIL package) marked 'PX4460' :
This custom IC has inside some passive parts (resistors and capacitors) needed by the typical application circuit of the LA4460 amplifer and most of times internal capacitors fail causing a low or absent sound.I could try to repair the custom or install needed parts directly on PCB (board is already prepared for this) but I opted to replace the part with a reproduction of mine :
In this way the sound was restored loud and clear.Repair accomplished.
P.S.
Here is the origanal post about the 'PX4460' reproduction I made time ago :
https://www.jammarcade.net/gals-panic-repair-log-and-kaneko-px4460-lpf6k-reproduction/
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