Battery corrosion on CPU chip ? ? ?

CykoMF

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Question for the experts here. See below.
I'd like to post this photo and get some opinions about it.
I.E. Think this is the cause? & What can I do about it?

attachment.php


In case you haven't been following my ongoing battle to resurrect this Godzilla machine, located in another thread.
Here's a little background...

Sega machine with the AA batteries mounted on the board, leaked, cleaned up, socket replaced, still having problems. Noticed this acid corrosion sandwich.
 
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Get a new game ROM, and hope you got the rest of the damage off of the cpu.

The crap from the batteries will keep on eating and spreading. Can be tough to eradicate.

John Wart likely has the game ROMs http://www.pinballroms.com/ or you can downlaod them from stern's website if you burn your own ROMs.

LTG :)
 
electrons flowing through dissimiliar metals can act like a battery over time even if there is no battery. the metal of the socket and the board traces coupled with the chip legs, all kinds of funny things can happen with electricity. oxidation is seen a lot as the cheap ass metal just can't handle the trillions of electrons flowing through it and the metal starts to scale or break down and create resistance to electron flow and make the chip short/open/not work. the excellent conductive metals like copper, is probably too soft for the chip legs and gold/ silver too expensive for that matter although i have seen gold legs on EPROMs quite a bit. aluminum might be too soft too or not last a long time i dont know, maybe they are aluminum. could be whoever made the chip was trying to save money and got a bad batch of pot metal from somewhere and its breaking down faster. lasted long enough in their eyes i guess

funny how the other chips in the picture look brand new
 
I have used diluted vinegar with a cotton swab to neutralize the acid.

The quicker you address it, the less problems you have.



Good luck!
 
Assuming that's a new socket that you just replaced, you can likely clean up any residual crud off that EPROM with a toothbrush, and diluted vinegar as suggested. Rinse it off afterwards, let it dry, and if nothing else you've helped prevent further damage. Any crud is going to be on the outside, so odds are good that you can clean it up sufficiently.

Otherwise, if you have access to a burner, you can verify it checks out, and otherwise burn a replacement - but if the EPROM was bad, I don't think the game would be booting.
 
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This is CPU,not Game ROM

If so, it would be the first CPU I've seen in a pinball machine with 32 pins.

Looks like a game ROM to me. Labeled CPU because it's the one that the CPU runs. As in, not the sound ROM.

I would try a new game ROM but that one doesn't look that bad. The best thing to do with a bad MPU is use Leon's test ROM and go through everything.

EDIT: Also, when dealing with batteries it's important to note what kind of battery leaked. If you're dealing with lead-acid batteries vinegar is not going to neutralize the corrosion. That will only work with nickel cadmium batteries.
 
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If so, it would be the first CPU I've seen in a pinball machine with 32 pins.

Hell, I don't think I've ever seen a 32-pin CPU........on anything!:D

To the OP, that's not a factory socket. Someone has replaced that....might want to look over their work.

Edward
 
Hell, I don't think I've ever seen a 32-pin CPU........on anything!:D

To the OP, that's not a factory socket. Someone has replaced that....might want to look over their work.

Edward

Yeah, that socket is not from factory. I sent it to him after I had a battery game eprom issue on a South Park. Same symptoms. I had no continuity from chip leg to test point. Thought is might me a socket issue due to battery acid damage. Looks like it might just be the game eprom. I would check the continuity of the legs of the chip to test points on the board and order a new chip. That one looks a little rough. If the chip continuity test okay I would remove chip, neutralize, let dry and replace with new chip. Just my two cents. I think you are getting close!
 
Hey Guys,
Thanks for the input!

I did give it a vinegar doush about a year ago when I first discovered the leakage.

Also changed the socket (THANKS MES!)

I tested for positive continuity from the top of the chip legs to each of the test points, on both sides of the board.

I also went back and 'sweated' each connection, just in case, to eliminate any chance of cold joints. Still no change.

I pulled the funky chip and gave it another cleaning, soaking it down with vinegar water followed with a careful wire brush scrub. It's a little cleaner but still no change.

Just ordered a replacement chip from John Wart.

Fingers crossed!
 
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