Playboy
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I am looking for opinions on whether or not this board appears repairable, the damage goes up both sides of the board but most heavily in the lower area where the battery was. I have never done board repairs, no opposed to trying, I'd love to keep everything original in the game, but if the board is a lost cause I'll move on and get an alltex board for it. Thanks for any and all opinions.
Quoted from ForceFlow:This is looking promising for removing corrosion: https://pinside.com/pinball/forum/topic/stripping-battery-corrosion-with-a-strong-acid
Thanks for the link, looks like i'll be making a trip to the store. I did vinegar on it today so hopefully that helped a little, until I can hit it with the stronger stuff.
Update: I have done a couple sessions of cleaning the corrosion off and this is what it's looking like now. I used a computer power supply to boot the MPU up. The LED will only go up to 4 flashes, so missing two more and I know the 7th won't occur being out of the game.
Quoted from barakandl:Nice job stripping the corrosion. No 5th flash is complaining about U11. It is definatly in the corrosion area. I imagine U11 socket is damaged. Those fairchild PIAs do not hold up to well either, the legs tarnish really bad over time.. You may lose some legs on u10 / u11 if you pull them from the sockets. But you can try and clean up the pins on them.
Thanks for the lead on what to look at first!
Quoted from barakandl:Nice job stripping the corrosion. No 5th flash is complaining about U11. It is definatly in the corrosion area. I imagine U11 socket is damaged. Those fairchild PIAs do not hold up to well either, the legs tarnish really bad over time.. You may lose some legs on u10 / u11 if you pull them from the sockets. But you can try and clean up the pins on them.
pulled out U11 out with no issues, got its legs all nice and clean, they were black from dirt. But I could tell that some of the leg sockets were filled with black junk also, any good way to cleaning those out? I put the chip back in to try it, but still only 4 flashes. Maybe the junk in the sockets is causing poor connection. The corrosion doesn't appear to have gotten under U11, it does look like U8 got some under it. I need to clean U10 yet its legs are all black from dirt also at least the exposed parts.
Quoted from ForceFlow:You will need to replace the socket. It's pretty much a must on these boards.
Should I do all the sockets? Going to likely order a corrosion repair kit from great plains along with a bunch of other things from them for the other boards.
Quoted from barakandl:Unless you are highly skilled at replacing chips and sockets i would go at it very slow. Start with just U11 socket.
It is possible the PIA is faulty too, they have pretty decent failure rates. The one in U10 is identical to U11, they can be rotated.
Luckily I have a friend with access to proper desoldering tools and willing to help with the desoldering. I haven't invested yet in a Hakko but its on my list. Should every component that was touched by the corrosion be pulled and replaced just to ensure or reduce possible future issues?
Quoted from ForceFlow:You will need to replace the socket. It's pretty much a must on these boards.
updates:
replaced the sockets for U11, U10, U8, and replaced U14 since corrosion had reached some of its leg, I also replaced the PIA. The mpu now completes all six flashes on the bench. Next question is, should I go and replace all the other components that the corrosion touched or just remov the old solder and resolder them with fresh? I had already removed all the old headers and will be installing new ones since they originals were so tarnished. Any other "house keeping" things I should do?
Quoted from Arcane:Now that you know that your board is good, I would try to carefully (emphasis on carefully) replace all the bad looking parts. At least you know you will have something reliable down the road. By spending a little bit of money on new parts and some time, you can save yourself $200 of Alltek board and keep the pinball machine in its original state, which is very rare nowadays.
Yves
Thank you. What is the best solution for the ground plane, it is bare copper after cleaning all the corrosion off. I've seen people state to either flow solder over it or clear nail polish to seal it. Is one better then the other? When you say bad looking parts, do you mean if the corrosion went up the component leads replace them? After cleaning the board with the toilet bowl acid almost all the small components that were "touched" by the battery leak have clean leads, at most numerous are light on solder now at the board surface because the corrosion and cleaning process removed a good amount of bad solder. That's why I wasn't sure if I should just remove the old solder and put fresh in or just for the sake of being super thorough replace each component. I picked up a Hakko so i can desolder much easier now. It made quick work of the header pins, I love it. Thanks again for all input, this is my first mpu repair job and I love the tedious nature of it.
Quoted from Arcane:Now that you know that your board is good, I would try to carefully (emphasis on carefully) replace all the bad looking parts. At least you know you will have something reliable down the road. By spending a little bit of money on new parts and some time, you can save yourself $200 of Alltek board and keep the pinball machine in its original state, which is very rare nowadays.
Yves
Update:
The board is basically done just need to clear coat the bare copper. Completed a corrosion kit plus replaced several other components. All new header pins, replaced sockets for U8, U11, U10. Did the ground mod for J4 pins 18&19. Bench test boards does 6 flashes. Now I will be pulling out the power supply/rectifier board to do maintenance on it. Some pictures of the board now, not superb work I'm sure but was my first time working on a pinball MPU. And I know I still need to clean up the rosin residue.
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