Working on Future Spa. Stupid me. I did the upgrades to the SDB, new electrolytics, ground mods, and tied TP1 and TP3 together. Well, actually I tied TP1 and TP5 at first and blew the 5V-4A fuse on the power supply. Then I found the jumper I had installed wrong. So I fixed the jumper, now TP1 and TP3 are tied together, but when I power up, I get a solid LED on the MPU board. No flashes or flickers, just solid. The voltages on the TPs are reading in range. What have I ruined?

Well, it's been powered down for an hour so everything is cold.

Removed all the socketed chips from the over voltaged board (see picture) and put them in a known good board and installed in Future Spa. All works correctly so I have concluded all the other boards in Future Spa are good. All the removed chips are good. So the issue is with the pictured board that saw the over voltaged 5v circuits. Can someone suggest where or how to test further the remaining components?

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Should I put all the socketed chips back in before check u15 u16?

On my logic probe, the pulse light turns solid when checking 8 and 11 on U15. Checking my other game that has booted up properly, my probe reacts the same...solid pulse light on pins 8 and 11.

I took all the socketed chips from the over voltaged board and installed in another MPU board. That board boots fine.

Clarification: Checking U15 pins 8 and 11 the pulse light was on on both boards I tested, but on the bad board the green "level" light was on at the same time, whereas on the good board the "level" light was off.

Replaced U15. Game boots! Only weird thing is I have this board in Star Trek now and only playing chime sounds, not all the weird sounds. I've set the dip switches for sounds like I had before in Star Trek. Any thoughts on this appreciated. EDIT: problem solved. Dirty dip switch.