Hi guys,

I'm repairing a Dolly Parton, which has stood uncovered in an open shed for the past 16 years.

After some preventive maintenance and fixes I got the game going without any major issues. One of the feature lights wasn't working and the 5101 socket is a bit flaky. I went to troubleshoot the light issue and was in for a nasty corrosion surprise on the back of the lamp driver board.

I took out the battery a while ago and it hadn't leaked if I remember correctly. I'm starting to question that now since there is some corrosion near where the battery once was (see R134, R29, and the capacitor next to R23). But the worst damage seems to be near the mounting brackets and screws on both boards?

I have dealt with alkaline corrosion in the past, but nothing like this. I believe these boards have a NiCad battery on them, is it the same procedure? Did this even get caused by the battery? Hope someone can point me in the right direction on how to proceed with this one.

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The lockdownbar holder and transformer mounting bracket have some corrosion on them, but they're by far not as bad. Actually the machine is in pretty good shape considering the situation.

Maybe a previous tech has replaced a corrosion-damaged MPU at some point and didn't bother to clean/replace the mounting brackets, screws and check the lamp driver?

The damage on the lamp driver board is towards the mounting bracket, and not below the battery. The component side is totally clean.

The strange thing is, the corrosion is also on the mounting screw on the top right corner of the MPU. I was also leaning towards galvanic corrosion, but you'd think it would be all over the backbox.

Maybe "its the best of both worlds"?

Edit: to add, i've tried putting some vinegar on the affected metal brackets (not on the PCB's yet), to see if it would have any effect, and it does seem to clean it up a bit over time, but without the satisfying hissing sound you normally get

Thanks for the solid advice everyone, I'm confident i can fix the issues with the MPU and mounting brackets in a decent way now.

I'm not yet sure what I'm going to do with the lamp driver. It's magically fully working right now apart from a broken scr...