I recently purchased a Big Game pinball (early Stern) as a parts machine to fix my Cheetah. When I got it home, I reseeded the rectifier board turned it on and the game started right up! It started a game and almost all switches and lights worked, I couldnt' believe it.

I then decided to remove the battery and put a battery pack on the MPU. went to radio shack and bought the same battery pack and diode 2n4001 that's on my Cheetah and installed it the same way. Went to turn on the game, and now it wont. It runs through the boot up and makes all the 7 chimes, but when I hit the start a game button, nothing. It has credits loaded. A ball is in the kickout hole, although I don't think this is necessary on old Sterns'.

When I run the diagnostic tests, all solinoids fire and almost all lights light up. it just won't start the game, and I can add credits.

once again, it worked fine for about 4-5 days. Worked just great until I added the battery pack. I have since removed the battery pack and still same issue.

one more thing, I noticed that the MPU has a little bit of solder from the negative terminal on the board where the (-) side of the battery connects when I added the battery pack. When I look at the traces on the board, it looks like this shouldn't be a problem but its the only thing that has changed so I wanted to mention it. I included a pic.

Thanks for any help!

BarakandI, Thanks for the reply!

I am a bit of a noob at repairing and with vocab/terms. Ill try cleaning all the connectors tonight. You're talking about the .156 molex connectors, correct?

Do you think the MPU is fine with the solder or the slightly removed paint near the (-) socket? Did my pic even upload? I didn't see it.

About Cheetah vs. Big Game. Since Big Game started, I think its no longer a parts machine I plan on fixing them both if I can.

I'll post any updates...

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Thanks Schertz! The step by step pics are really helpful!

I just managed to post my pic. Can you see where the paint is coming off and some of the solder is in there. I removed as much as I can and I now think all that's left is the metal underneath the paint. I hope its ok. I think so.

I tried the "poor man's" fix and that seemed to do it! I now have to order a Molex crimper...I see that Marco has one for $25, is that a good one? Do I have any other options?

I plan on reflowing all the solder on the header pins. I'm getting better at that.

Want to make sure I am getting the terms right...the "header pins" are the male pieces already on the MPU and the "connectors" are the female pieces on the wires?

Thanks Jason and BarakandI for the insight and fast responses!

Many thanks!