I thought I'd post this in case it helps someone in the future..
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Scramble board boots to yellow screen:
- Found a few visibly broken traces on main board, repaired them.
- No clock at Z80 CPU on main board.
- 6MHz clock out of the 74LS368 inverter at 7A is toggling, but has a very low amplitude, especially where it goes into the 7474 flip-flop at 7M.
- Socketed and replaced both the 74LS368 inverter at 7A and 7474 flip-flop at 7M .
Now the screen shows the blinking stars in background, but with static garbage characters on top instead of the grid pattern:
- Socketed the main board Z80, hooked up the Fluke - ROM sigs are all good, RAM and VRAM are good.
- Poked around a bit with a logic probe.. while doing this I noticed that the custom IC at 6J on top board is quite warm, but apparently this is normal. Input signals never toggle though.
- Traced those signals to the 8255 PPI at 1D on top board. Holy crap, that 8255 is hot as hell. Socketed and replaced it.
Board boots normally now, gameplay works fine, but no sound:
- Board is missing 2SC2320 transistor, VR200 pot, M51516L amp, and there are a few cut traces in that area. Looks like previous owner removed all those components and rewired the audio output to an external amp board.
- Replaced those missing components (including the heat sink, which I found sitting in the bottom of the cabinet) and fixed the broken traces. Sound works again.
===
Yay, my Scramble is now back from the dead!
I can't wait to get the cabinet restored so I can start playing it.
===
Scramble board boots to yellow screen:
- Found a few visibly broken traces on main board, repaired them.
- No clock at Z80 CPU on main board.
- 6MHz clock out of the 74LS368 inverter at 7A is toggling, but has a very low amplitude, especially where it goes into the 7474 flip-flop at 7M.
- Socketed and replaced both the 74LS368 inverter at 7A and 7474 flip-flop at 7M .
Now the screen shows the blinking stars in background, but with static garbage characters on top instead of the grid pattern:
- Socketed the main board Z80, hooked up the Fluke - ROM sigs are all good, RAM and VRAM are good.
- Poked around a bit with a logic probe.. while doing this I noticed that the custom IC at 6J on top board is quite warm, but apparently this is normal. Input signals never toggle though.
- Traced those signals to the 8255 PPI at 1D on top board. Holy crap, that 8255 is hot as hell. Socketed and replaced it.
Board boots normally now, gameplay works fine, but no sound:
- Board is missing 2SC2320 transistor, VR200 pot, M51516L amp, and there are a few cut traces in that area. Looks like previous owner removed all those components and rewired the audio output to an external amp board.
- Replaced those missing components (including the heat sink, which I found sitting in the bottom of the cabinet) and fixed the broken traces. Sound works again.
===
Yay, my Scramble is now back from the dead!
I can't wait to get the cabinet restored so I can start playing it.

