AS2518-35 MPU Battery damage repair

dasvis

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-- 1982 Bally Mr & Mrs Pacman --
My first attempt at installing a GPE battery corrosion repair kit. Not totally finished yet, still need to address some ground issues, but here are a few pics.
Any comments, or helpful tips?
39start.jpg

36start.jpg

43ratty.jpg

51stripped.jpg

67done.jpg


Have already rebuilt the rectifier board & voltages are within specs. Installed complete kit for high & low voltage on the solenoid driver board. Starting on Squak & talk board today.
 
Just a tip - check both 6821's...both of those on mine (original 6820s) had rotted and broken legs. I was able to pull them out 100% intact but almost breathing on them made the legs fall off. Had missing digits on the display, sounds not playing right, improper solenoids, etc.

Arcade chips has em and shipped quickly for what its worth.
 
Yeah, I'd replace the two 6821's, they're buggy when they're old like these (30 years old now!!!), and it's better to have known good ones in there, so when the game starts doing weird shit you know it's not the 6821's.

On your squawk and talk, make sure to recap it, particularly the smaller caps. I had a mr. and mrs. a few weeks ago, some of the sound was missing... eventually I figured out there's one 1uf cap that ALL the digital audio goes through! Replacing that 1 cap fixed all the audio issues.
 
Yeah, I'd replace the two 6821's, they're buggy when they're old like these (30 years old now!!!), and it's better to have known good ones in there, so when the game starts doing weird shit you know it's not the 6821's.

On your squawk and talk, make sure to recap it, particularly the smaller caps. I had a mr. and mrs. a few weeks ago, some of the sound was missing... eventually I figured out there's one 1uf cap that ALL the digital audio goes through! Replacing that 1 cap fixed all the audio issues.

Good point, I just ordered a kit that contains:
1 ea. 6800 Processor (40-pin)
2 ea. 6821 PIA (40-pin)
3 ea. 40-Pin Machined Socket
- Plus a couple of 20 pin machine socket strips.

What the hell, soldering those on the board is no where near as bad as I had expected that it would be.

- Yes, I rebuilt the S&T board this morning with a full cap kit from Big Daddy's. Works great!
 
Yeah, I'd replace the two 6821's, they're buggy when they're old like these (30 years old now!!!), and it's better to have known good ones in there, so when the game starts doing weird shit you know it's not the 6821's.

I would be much more confident in a crusty looking 6820 that I had tested and installed in a new socket than a "new" 6821 in an old crappy socket. I have not found PIAs to be buggy in general assuming that I have tested all the outputs. Sure they fail but I wouldn't replace them unless I had tested them and proven them to be unreliable. If you're going to replace working ICs start with the 5101 RAM and install an NVRAM adapter. The sockets on the other hand are crap. They are something that does actually wear out with time and they were not that great in the first place.

I would definitely have replaced most of those sockets. It's a lot of work and easy to short-cut around but the key to reliability is going to be with new sockets everywhere. It took me years to finally realize that.

EDIT: I didn't realize you were the guy with the display problem. That would have made things easier. I could have just said "socket" :)
 
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I would be much more confident in a crusty looking 6820 that I had tested and installed in a new socket than a "new" 6821 in an old crappy socket. I have not found PIAs to be buggy in general assuming that I have tested all the outputs. Sure they fail but I wouldn't replace them unless I had tested them and proven them to be unreliable. If you're going to replace working ICs start with the 5101 RAM and install an NVRAM adapter. The sockets on the other hand are crap. They are something that does actually wear out with time and they were not that great in the first place.

I would definitely have replaced most of those sockets. It's a lot of work and easy to short-cut around but the key to reliability is going to be with new sockets everywhere. It took me years to finally realize that.

EDIT: I didn't realize you were the guy with the display problem. That would have made things easier. I could have just said "socket" :)

Sockets & 6821 RAM on the way - thanks all for the replies.
Will post photos & an update once the repair starts...
 
The sockets on the other hand are crap. They are something that does actually wear out with time and they were not that great in the first place.

I would definitely have replaced most of those sockets. It's a lot of work and easy to short-cut around but the key to reliability is going to be with new sockets everywhere. It took me years to finally realize that.

I think that you are correct. I carefully pulled the RAM chip out of U11 & then gently pried the plastic socket housing off to reveal the guts of the thing. Yes indeed I did find some corrosion there, mostly on the battery side. Have desoldered all of the old terminal clips and cleaned the area up -- should have the new socket soon. These are really not too bad to remove once you have done a couple, just time consuming.
Thanks all for the suggestions, you guys are amazing.
 
You do pretty good work.

Ive discovered a quicker way to clean- sandblaster..

trick is to hold the pcb at a angle and keep the tip far far away from the pcb, getting just close enough to clean..


but like i said you did a pretty good job just with the sandpaper there.. man, getting that old oxidized solder out is the worst part, after that it aint so bad..

WHever i work on these bally machines i also add a ground wire that loops to each pcb and theres a eyelet at each end , you use one of the pcb screws to hold it down( after cleaning the area under with sandpaper to ensure a good contact area of course).

fixed alot of odd ground issues that way.. Yeah yeah, mabye it isnt "correct" or whatever but its a quick asy way to make your previously corroded stff a little more dependable.
 
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