Found some free to time to dig through a box of Crystal Castles boards we accumulated over the years. Most of these were straightforward repairs, but I'm not complaining, here you go:
Boots, coins up but Start Buttons don’t respond (12/17/19)
- Inputs at buffer chip at 11C seemed to be behaving normally.
- Swapped Pokey chip at 3D to fix the problem.
White Screen, Swirl sound on boot (12/17/19)
- Board sounded close to working, had a white screen like other boards on boot and the swirl sound at boot, but stopped there.
- Quick inspection show rom at 1N was a revision 205 rom, other roms were 300 series revisions. Installed 305 Rom at 1N and board booted properly.
Garbage on Screen (12/17/19)
- Board was beeping on booted, beeps indicated bad ram at 4E.
- Replaced 4416 at 4E to fix the board.
Dead, Reset Low (12/12/19) –
- Poked around reset circuit, noticed Q2, 2N3904 transistor tested differently than a known working board.
- Replaced, Q2, reset line now high, board still not working.
- Swapped 6502A, board booted up. Reinstalled original 6502A, board also worked. Reseating 6502A fixed problem.
Watchdogging, Garbage on Screen (12/12/19)
- Swapped 6502A with known good processor. Board works!