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Thread: 5150 early revision motherboard rescue

  1. #1
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    Default 5150 early revision motherboard rescue

    5150 16-64k board, corroded with mouse feces and battery juice from a quadboard. Mmmm, delicious.

    DSC00376.jpgDSC00375.jpgDSC00374.jpgDSC00373.jpgDSC00372.jpgDSC00371.jpg

    Will it boot? Going to try it ... but first, a cleaning and close examination.

    It is outfitted with the '78 Intel CPU w/ interrupt bug and the 10/19/81 BIOS and 64k.

  2. #2

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    Good luck!
    Should work after a clean and inspection.
    Can't imagine what that multifunction card looked like if it leaked all the way down there.
    In my 5150, I had a multifunction card (DFI MF-100) that had somehow corroded all the traces off the back of the adjacent IBM CGA card. Corrosive vapuor? Or perhaps the machine was stored on its side. I did manage to fix the CGA card, and the multifunction card too, after repairing some traces and replacing the battery with a button cell holder.
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  3. #3
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    Does not POST ...

    After a good cleaning, the board looks much better, but I could not get it to POST at all, even with minimal 16k RAM configuration. The board looks fine though, so no doubt it will can be saved.

    Likely culprits? A few of the logic ICs have legs which are very badly rusted. Not only do they look terrible, it is possible one or more of the rusted ICs are not working. I may just go ahead and replace these chips before doing anything else. Bank 0 is not socketed, so if the lack of POST is due to bad ram , I'll also have to socket and replace Bank 0. I think I'll start with the logic ICs first. I also need to check conductivity on the 2 corroded bus slots as these should be checked for shorts too. No blown caps apparent, but these should probably be checked for shorts too.

    As for the Quadboard ...

    There was some corrosion which I cleaned, but a few of the edge pads are damaged. I was able to get the card to work (w/ RAM error of course) if it is positioned at the right spot in the slot, but the pads being damaged are causing problems for this card. Maybe a candidate to try pad repair or use it for parts. It is an early rev quadboard with the black bracket.

  4. #4

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    Quote Originally Posted by chris_nh View Post
    Does not POST ...

    After a good cleaning, the board looks much better, but I could not get it to POST at all, even with minimal 16k RAM configuration. The board looks fine though, so no doubt it will can be saved.

    Likely culprits? A few of the logic ICs have legs which are very badly rusted. Not only do they look terrible, it is possible one or more of the rusted ICs are not working. I may just go ahead and replace these chips before doing anything else. Bank 0 is not socketed, so if the lack of POST is due to bad ram , I'll also have to socket and replace Bank 0. I think I'll start with the logic ICs first. I also need to check conductivity on the 2 corroded bus slots as these should be checked for shorts too. No blown caps apparent, but these should probably be checked for shorts too.

    As for the Quadboard ...

    There was some corrosion which I cleaned, but a few of the edge pads are damaged. I was able to get the card to work (w/ RAM error of course) if it is positioned at the right spot in the slot, but the pads being damaged are causing problems for this card. Maybe a candidate to try pad repair or use it for parts. It is an early rev quadboard with the black bracket.
    Supersoft diagnostic ROM can diagnose bad RAM in bank 0. Try that. You'll need to program the diag ROM to a 28C64B/27(C)64 and make a lil adapter to go from 28-pin to 24-pin. I've used this to determine the bad RAM chip in bank 0 on a 5150 board.
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  5. #5
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    Thanks, yeah I might try that. I need to get a ROM programmer anyway, so this might be a good excuse. Is there a diagnostic rom that I can use without an adapter?

  6. #6

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    Quote Originally Posted by chris_nh View Post
    Thanks, yeah I might try that. I need to get a ROM programmer anyway, so this might be a good excuse. Is there a diagnostic rom that I can use without an adapter?
    Well the original Supersoft diagnostic ROM would come on an original 24-pin 8Kx8 ROM.
    But 24 pin 8K ROMs aren't a thing anymore. The easiest way of using the diagnostic ROM is to use a common 27(C)64 EPROM or 28C64 EEPROM, and adapting the pinout.

    I make and sell such adapters in my store in my signature. They can include the ROM too. But it will take a little while to get to you with the cheapest shipping option.

    If you're confident in replacing chips etc, then I'm sure you can whip up the ROM adapter on some prototype board with a 28-pin IC socket and some machined header pins.
    The pinout for adapting the ROMs is on miniszerodegrees.
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  7. #7

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    Quote Originally Posted by chris_nh View Post
    Does not POST ...

    After a good cleaning, the board looks much better, but I could not get it to POST at all, even with minimal 16k RAM configuration. The board looks fine though, so no doubt it will can be saved.
    Cleaning won't help with any traces that may have sustained damage. There's a lot of corrosion on one or two slots and it could easily have caused damage to traces under the connectors.
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  8. #8
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    Default

    It seems really like a trade off between which method is less work ... it might be easier to just socket the 9 chips in bank 0 and put in a known good set of chips, than to make up an adapter, burn a rom, etc. just to troubleshoot. I dunno ... I think the logic ICs are a good place to start first anyway because the legs are quite bad and I suspect the corrosion got into the chips. If that doesn't do the trick, then I'll get into bank 0.

  9. #9

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    Take a look at the pinout. The pins almost line up. Ana adapter is simple.

    Investing in a programmer is recommended. Get something like the TL866II Plus.

    For speed, you may be able to get an AT28C64B EEPROM, and maybe an Arduino, and Google a programmer, or find someone with a programmer.

    I wouldn't have the heart to snip off 4116 DRAMs unless they were confirmed bad. I'd leave it to a last resort. Unless you have a proper desoldering station to remove those chips intact. A solder sucker will give you grief with that multilayer board.
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