Could use some DE experts here.
DESW's L/R relay was getting flaky -- failing after a few games and firing on only flashers instead of coils. I resoldered relay pins, replaced Q29 with a TIP122 (or so I thought, the transistor I ID'd had previous, nasty work ... we'll get to that) and put the board back in. No dice.
Thought it was the relay so I Picked up a Rottedog PPB just to throw in there while doing work (this game is a big earner on location). None of this fixed the issue with the L/R relay. So: I presumed it was the PIA chip on the MPU, and, again, picked up a Rottendog MPU board to thrown in there while doing work on the other board(s).
Tonight I put in the new MPU. Things got interesting:
The L/R problems were solved! All coils and flashers fired properly.
All controlled lamps, however, weren't working.
A fuse was out above the big cap on the left (F1?). Replaced what I'll call F1 above the big cap, mounted on the backbox. This fixed controlled lamps.
Started a game. All well, but the motors were all out on the death star, bar target, and R2.
Traced motors to F2(?) above the big cap. It was blown, too. Weird. This did not fix the motors.
At this point, I thought there must be another fuse that was out that maybe I knocked out removing and testing boards or whatever. I found one, F5 on the Power Supply board. Replaced that (4A, slo blo). I also, at the same time, noticed a yellow wire connector at CN10 on the power supply board that was *not reconnected* after I removed that board. Oops.
After plugging CN10 in, and replacing that fuse, I power her on.
Q28, the GI transistor (?) spouted a 3 inch flame on my new board. Crud.
Which brings me back to "Q29" way back at the beginning. I wasn't even doing work on Q29, ever. I had replaced Q28 originally as it was loose in its sockets and had burned at some point and I just visually ID'd it and, well, made a mistake.
So I did solve the L/R problem with the new board, and I don't know how (maybe it was the PIA). But something is -and was- frying Q28.
If this is all a bridge rectifier, I just don't know what. Thanks in advance for the help!
Images attached of Q28 burned on the Rottendog, the fuses I was referring to above the cap, the fuses on the power supply board, and connector I missed.