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Thread: Motherboard corrosion repair questions and advice

  1. #1
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    Default Motherboard corrosion repair questions and advice

    I recently bought a MiTAC IH4077H board on eBay for $26 + tax and noticed a fair amount of corrosion on the keyboard port (the shield), top SIMM-72 slot, RS-232, Parallel, and floppy I/O ports, jumpers, resistors, capacitors, on a couple of chips, by the battery (terminal adjacent to the keyboard port), and parts of the AT PSU slot.

    I have plenty of distilled white vinegar and could use something to scrub the board with instead of using nylon brushes, which are a big no-no for the electronics. My question is, would soaking those spots affected by corrosion in vinegar suffice and would also recapping and replacing resistors and other items along the way with trace repairs if the traces are too far gone?

    Picture of the board (seller's photo) - Click on the image to get the full image that is the regular size:

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  2. #2
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    First, get rid of the barrel battery and have a look at the traces under and around it.

  3. #3

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    What about the traces on the inner layers? There's no way to see or repair them, is there? I've found that multilayer boards with as much as or even far less corrosion than the one pictured here are usually impossible to get working again. Surface traces are hard enough to fix. Those on the inner layers are impossible.
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  4. #4
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    One can but hope. The words of our senior engineer still echo in my head "a printed circuit board is no place for a battery". That was almost 50 years ago.

  5. #5

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    Quote Originally Posted by Chuck(G) View Post
    One can but hope. The words of our senior engineer still echo in my head "a printed circuit board is no place for a battery". That was almost 50 years ago.
    Prior to the silly notion of putting batteries on pcb's somebody came up with the idea of putting cylindrical shaped objects with perishable rubber seals filled with a similar corrosive electrolyte onto pcb's, they called those "electrolytic capacitors" but everybody knew they were a lot like batteries in terms of destructive power when they spewed their guts out. Surface mount electros are particularly bad as we all know.

    Then if that was not enough, somebody came up with the idea of putting batteries into sealed memory IC modules (like the Dallas NV rams) and they sealed them in there with good epoxy resin, which was thoughtful. Except when the battery goes flat and you lose the data, its very inconvenient and created a kind of "built in obsolescence" that sent many a good piece of lab gear to the dump.

    I wonder if its possible with enough high intensity transillumination & magnification to see the tracks in the middle board layers, I have not tried this, but it might be worth a go.

  6. #6

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    Quote Originally Posted by Hugo Holden View Post
    I wonder if its possible with enough high intensity transillumination & magnification to see the tracks in the middle board layers, I have not tried this, but it might be worth a go.
    Even if this were somehow possible how would you go about repairing those now, made-visible, inner layer traces? Knowing where the damage lies is one thing but being able to make a suitable repair to it is quite another.
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  7. #7

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    Quote Originally Posted by Stone View Post
    Even if this were somehow possible how would you go about repairing those now, made-visible, inner layer traces? Knowing where the damage lies is one thing but being able to make a suitable repair to it is quite another.
    Access through vias? Newer complex boards use buried vias - the older ones usually don't.

  8. #8

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    Quote Originally Posted by mcs_5 View Post
    Access through vias? Newer complex boards use buried vias - the older ones usually don't.
    Maybe, but we're discussing vintage boards in this thread, aren't we?
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  9. #9

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    Quote Originally Posted by Stone View Post
    Maybe, but we're discussing vintage boards in this thread, aren't we?
    Yes. So there's hope

    The vias are probably still tiny. But at least accessible.

  10. #10

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    Quote Originally Posted by mcs_5 View Post
    Yes. So there's hope

    The vias are probably still tiny. But at least accessible.
    Are you (personally) able to do repairs via vias?

    Have you ever done this type of proposed repair?

    If you have actually done this you are wasting your talents and should be doing laparoscopic brain surgery instead.

    And if you're just speculating...
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

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