Kickman logic board repair question

alfonzotan

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Hi, folks... I've had a Kickman upright out in my storage shed for quite a while now, and finally got off my keister to repair it. The monitor appears to be fine, but the game won't boot. So, on to the logic board.

I have two sets of boards, naturally, neither works. I was planning on mixing and matching the individual boards (there are three in the stack), but when I took a close look at them, I noticed that both had signs of a blown capacitor on the sound card. On one of them, that cap has not been replaced (first pic below). On the other board, it looks like the same cap blew and was then replaced (second pic). The bottom side of that second board is also odd, it looks like somebody deliberately or accidentally broke one of the traces in that circuit (third pic). The underside of the first board is clean.

According to the Kick service manual, the cap in question is CP34, a 10uA, 25V capacitor. According to Bally service bulletins and a couple of online sources, that cap was often installed backwards at the factory, and thus was a known failure mode for this board.

So my question is, how to install replacement caps in terms of polarity? Looking at the board, other capacitors have rounded ends towards the "+" indicator on the board; can I assume that the "+" for CP34 is marked incorrectly? It looks that way to me (see pic 1), since the rounded end of the blown cap is pointed at the "+" indicator on the board, and as noted above, a backwards cap in that slot is a known factory flaw. If the polarity marking on the board is in fact wrong, that would mean the replacement cap on board #2 was installed correctly.

Appreciate any suggestions on getting this machine working, but please bear in mind, replacing a cap is basically the upper limit of my soldering skills, and while I did have to take Circuits in college, that was 20 years ago, and (this should come as no shock to the EE's who've made it this far) I got a "D."
 

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Trace

Follow the traces for C34 back to other components and you will be able to tell what side is positive and negative. That cap will cause a failure. White screen, not booting, etc. Be sure to check your 5VDC and 12VDC. Kick/Kick mans are very particular on voltage. Most of the 90412 power supplies are failing by now but, they are not a huge deal to repair, rebuild.
 
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