Most of the time, if you’ve done a lot of them, repairs on WPC era games when it comes to boards are relatively straightforward; however, sometimes you get those that make you go the extra mile. This was a case of the latter.
The batteries on the CPU had began to corrode, but thankfully were isolated to the batteries and holder themselves. Once removed, I put on NVRAM at the client’s request and replaced the little 100uf cap on the CPU as well as reflowing the logic voltage input header.
I was told that the solenoids weren’t working, but flippers were, and that all fuses were good. On an older Bally, there’s a pretty straight forward possibility for a symptom such as this, but on a WPC game, that’s a pretty uncommon occurrence if not a fuse or power related.
They asked me to put a PPU5 no noise LM323k replacement on the board, which I did. For the cost, it’s really not a bad move these days. I replaced C2 and C4 as well.
C2 is a huge issue at this point if original. This one didn’t look too bad on the surface, but I smelled the old familiar fishy smell of electrolyte when I removed it. It had actually already gotten the LM7812 bad enough that I needed to remove it and sand down the traces and replace it as well.
Where this went the step further was once it was on the test fixture. No solenoid or lamps were working. Neither was the orange string of the general illumination even though continuity and the fuses were good.
Even though it wasn’t painfully obvious by looking at it, the electrolyte from C2 had crept under U1 damaging the blanking signal from U1 to the other 74LS374 chips down the line. It had also damaged the data signal that went down to the orange strand of general illumination circuitry.
After removing and sanding down U1’s traces, fixing the two lines that were broken, socketing and putting U1 back in, and sealing it all, the game passed all driver board tests.