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Thread: Need help w/ PSU for a Compaq SystemPro XL

  1. #21
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    That trace is not intact, it's vaporized. If there's still continuity, it's either because the soot left behind is conductive, there's a tiny sliver of trace left, or one of those mosfets/diodes died and went short circuit. In any case, that PSU just became a whole lot more difficult to repair because there are more faults to find and repair now.

    I'd stop wasting time on that thing and find a modern PSU replacement that will fit in the shell of the existing PSU. A Pico PSU like this:

    https://www.ebay.com/itm/223039942462

    Could be modified to work with your system pretty easily. You may need a -5v rail, which can be done by using a LM7905 and hanging it off of the -12v rail. The power draw is so low on -5v that it should be OK.

  2. #22

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    Quote Originally Posted by GiGaBiTe View Post
    That trace is not intact, it's vaporized. If there's still continuity, it's either because the soot left behind is conductive, there's a tiny sliver of trace left, or one of those mosfets/diodes died and went short circuit. In any case, that PSU just became a whole lot more difficult to repair because there are more faults to find and repair now.
    I agree. Luckily I have two more of them which don't have "Shadow Lord Caused Damage" but are still not working. I am going to start with the ESR meter and checking the diodes again...

    Quote Originally Posted by GiGaBiTe View Post
    I'd stop wasting time on that thing and find a modern PSU replacement that will fit in the shell of the existing PSU. A Pico PSU like this:
    Problem is not even the case. The issue is the weird mobo connector. The Compaq uses its own special connector and a ribbon cable to the motherboard. If it used a straight AT or ATX connector I would have done that already...
    Current Wish List: 1. IBM 7531 Industrial Series PC 2. NEC MultiSync XL (JC-2001) Monitor 3. MicroSolutions MatchPoint AND/OR UniDOS card 4. Compaq 14" VGA CRT Monitor (the one that came with the SystemPro). 5. Stacker HW CoProcessor Board MCA BUS. If you have any of the above for sale please PM me. Thank you!

  3. #23
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    Quote Originally Posted by Shadow Lord View Post
    The Compaq uses its own special connector and a ribbon cable to the motherboard. If it used a straight AT or ATX connector I would have done that already...
    Chop the connector off and chop the ATX connector off a power supply and match wires to voltages. I've had to do it several times for proprietary PSUs, and I'm currently working on a Mac SE FDHD which needs the same treatment.

  4. #24

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    Quote Originally Posted by GiGaBiTe View Post
    Chop the connector off and chop the ATX connector off a power supply and match wires to voltages. I've had to do it several times for proprietary PSUs, and I'm currently working on a Mac SE FDHD which needs the same treatment.
    I may not have been very clear: The PSU has two separate connectors. One is a Molex type connector and looks like to be responsible for power delivery. But there is also a thin ribbon cable going from the PSU to the MB. That would be much harder to decode with no basis of reference.

    Systempro XL Connector.jpg
    Current Wish List: 1. IBM 7531 Industrial Series PC 2. NEC MultiSync XL (JC-2001) Monitor 3. MicroSolutions MatchPoint AND/OR UniDOS card 4. Compaq 14" VGA CRT Monitor (the one that came with the SystemPro). 5. Stacker HW CoProcessor Board MCA BUS. If you have any of the above for sale please PM me. Thank you!

  5. #25
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    Didn't even notice that ribbon cable. It looks like it may be to monitor the power supply rails, the wires are too small to draw any current from.

    I'd try what I said in the above post and see what happens without the ribbon cable connected. The worst case scenario is the machine won't turn on because it can't monitor the power rails.

  6. #26

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    Quote Originally Posted by GiGaBiTe View Post
    Didn't even notice that ribbon cable. It looks like it may be to monitor the power supply rails, the wires are too small to draw any current from.

    I'd try what I said in the above post and see what happens without the ribbon cable connected. The worst case scenario is the machine won't turn on because it can't monitor the power rails.
    As a last desperate hail marry I am willing to consider this but I would really love to get one of my three PSUs into working condition...
    Current Wish List: 1. IBM 7531 Industrial Series PC 2. NEC MultiSync XL (JC-2001) Monitor 3. MicroSolutions MatchPoint AND/OR UniDOS card 4. Compaq 14" VGA CRT Monitor (the one that came with the SystemPro). 5. Stacker HW CoProcessor Board MCA BUS. If you have any of the above for sale please PM me. Thank you!

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