Quoted from The_Great_Man:When I was replacing the large capacitor - C10 - on the power supply, I spilled a small piece of solder - maybe 1/8" x 1/4" on the capacitor. I left it because I was not sure I could remove it. I did not think much of it but maybe that is causing some problems. When I just checked that capacitor with my DMM - I did not get a reading. Any thoughts on that screw up/
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Just getting caught up on this thread.. Getting solder on that cap like that is not a problem. Just be sure to check for other possible areas that may have splashes. You can gently scrape this one off .. make sure power is off and it doesnt fly elsewhere in the machine.
As for your other questions..
Technically you can boot the MPU without the driver board attached, but the stock ROM chips may prevent from getting anything useful out of it.
Additonally, the built-in diagnostics in games of this era are known to be incomplete.. ie a RAM/CMOS test does not test the entire chip, only a few locations within it, and therefore can give false positives.
If you want to eliminate the driver board temporarily from the equation you can disconnect it and then use the Pincoder Adapter/ROMs to test components on the MPU board:
https://pincoder.ca/index.php/2020/07/10/adapter-2020-06-23-0506
You can also download the ROM images and documentation from the Download menu on the main page:
You will find a .txt file for each test/ROM image that shows you how to run the tests.
With your game, it sounds to me like a RAM chip issue. The adapter/ROMs will test both RAM chips individually so you can isolate which one has any issues.
The CMOS/5101 test will test the ENTIRE 5101 (or NVRAM since you have it) and the coin door must be open for this test only.
Now that you have an NVRAM you should use the "clear_cmos" test (with coin door open) to clear out any data in the NVRAM chip, then run the original factory ROM and power on. This will bring you into audiit mode. Power off, then on again. This should bring you to attract mode and you can close the coin door.