I’m so backed up in the shop and doing everything I can to stay head down and move through as much as I can, but still trying to post as regularly as I can too. Many more boards and games ahead!
On a The Machine: Bride of Pinbot board set, the original CPU was completely corroded. The client had a Rocket CPU on the shelf, so I switched over the ROM. The RAM backup had both NVRAM and battery backup, which it only needs one or the other. So, I removed the batteries, set the DIP switch to read for NVRAM, and left it in.
On the driver board, I did the usual reflows I do and replaced C2, C4, and C5. On bench test, everything worked, but the logic voltage was very low at around 4.2vdc. I opted to install a PSU5 No Noise for the LM323 which has an adjustable voltage pot. This brought it up to an acceptable 5.1VDC off the driver.
The sound board had a blown C28. This is relatively common on WPC sound boards as they undervalued these little tantalum caps. They can go rather catastrophically when they do. This one, however, blew two traces off the back of the sound board! That was a first. I patched the traces with kynar, replaced C28, replaced the two 4700uf filter caps, found C41 was also badly popped and replaced it as well. On bench test, everything sounded good, but C26 decided to give up then. So, I replaced it as well and let it sit and burn in on the test bench for awhile. That got the sound board all passing.
The other board for the day was a Baby Pac Man Vidiot board with bad/scratchy sound. The owner had done some work to it and done a good job overall. However, U32 which had been replaced, was replaced with a 74LS164N when it is supposed to be a ZN 428E 8 DAC. I had a spare Vidiot here at the shop I pulled one off of and ordered a replacement for it. I then put this Vidiot on my home-made bench test setup and tested the sound, blink config, and video output. I can test everything here but the com lines with the -33 CPU.