Hey RingMaster!

I had a similar problem with my BOP, one of the many pins in my home collection. One day I turned on the BOP power switch and heard a big buzz noise. The system had returned to "factory settings". I changed the batteries on the CPU board in the back box. I then opened up the coin door to try and reset my game utilities settings. The Enter/Test key would not work. I took the CPU board out of the game, looked it over good, but I could not find any problems visually. No burnt marks, not broken traces, not missing components. I did find some green crud on the upper legs of some of the chips directly below the battery holder, but nothing major and I simply cleaned them up.

I put the board back into the back box and reconnected the plugs and ribbon cables. The same problem occured. I removed the plug on the bottom left side that traced to the enter key and tried shorting pin #9 against ground (this pin traces to the enter/test key). Nothing. (I also shorted another pin that traced to volume up just to make sure I was shorting to a good ground and this worked).

After reading your comments above, I pulled the CPU board out again, heated up my fine soldering pencil and touched each soldered in pin from U13 on the underside of the CPU board - just enough to remelt the solder. I did the same for the chips that had crud on them that were located under the battery holder. I put the board back in the back box and viola! The BOP enter/test switch was back in action! It has been working for several weeks now with no problems.

I had successfully tried this trick several times before. Sometimes the chips are not well soldered to the pads at the factory and just need a little touch up. I do still have the problem with the loud buzz at start up. I'm sure I need to replace all of the big caps on the power board - they're bloated!

Thanks for your information! It was helpful in isolating which chip to look at - without having to use a logic probe - and it confirmed my suspicions that the problem was related to a chip on that board.

BTW - after getting the enter key fixed and shopping the playfield I played the game and got the Grand Champion High Score!