Got a very intermittent (20-200+ games between, average 150+) issue where during gameplay, I hear a beep, the all segments of all displays light up, and if I don’t turn it off quickly enough, it will blow F2. I’ve seen the kickback lock on and believe be heard the knocker kick off when this happens, too.
Checked all coils and their diodes test good. Haven’t gone to the point of replacing the diodes yet given the intermittent nature.
Generally, it happens relatively soon closer to initial power on, but can happen a couple dozen games in. Can play for hours after it happens without issue. Can also play dozens of games from a cold boot and never see the issue.
I’ve verified at TP2 that it has exactly 5.00 volts (even at cold power on) and have reseated the connectors from the power supply. There are several chips that have been socketed as part of repairs, so gave those a good push to ensure they are seated well. Running the CPU checks (SW2) returns a 0 and it goes into attract mode.
Didn’t do this in the past since I powered it off ASAP, but the most recent occurrence I left it running long enough to open the backbox. The CPU board showed a 7 on the LED on the CPU. After replacing the fuse, I played another 50 games without incident. Pinwiki only cites codes 0-5 for the System 11 (prior to 11A) boards, so not sure if that corresponds to U54 failure like with later System 11s.
I haven’t yet pulled the board to reflow connector pins (my initial guess) but wondering if folks have any other ideas. Not that I want issues, but wish this were a bit more consistent so I could get to root cause.
Many thanks in advance!