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37222Compaq Deskpro 386/25M Power Supply

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  • chetwyndplace
    Aug 21, 2014
      The Compaq Deskpro 386/25M that I have posted about in a few other messages here through the year just had a power supply failure.Hoping I could just create a modern ATX power supply adaptation, I removed the power supply from the system and testing, only 1 of the 24-pin is providing any voltage.

      However, nothing about this power supply seems standard in any way.

      The pin-outs on the 24-pin connector that connects directly to the motherboard don't seem to match anything I can find online, even on the fantastic site http://pinouts.ru

      Here's what I've come up with so far, mostly based on tracing the connectors on the PCB board back from the standard connectors for peripherals and hard drives.




      Please see my Google Drive-hosted pictures of the power supply here, as well as some links to relevant but unhelpful search results.

      Compaq Deskpro 386/25

      I tried making my own adapter from a modern ATX power supply already, just leaving unconnected the connectors I mark in purple as "mystery", but I get no video-out or boot sequence from the motherboard.

      I find it worthy to mention that the one pin I identify as +5v and the "only pin with voltage after failure" causes some LEDs on the motherboard to light up, and without it, the motherboard is dead, even with the known +5v and +12v pins connected to a modern ATX power supply.

      The board says

      Board No. 002021-001
      Diagram No. 002020
      Spare No. 129069-001

      All Google searches turn up only ancient parts-house listings for way-overpriced hardware. All pinout searches seem to direct to 24-pin connectors that can't possibly be right, based on my tracing the PCB connections to known standard peripheral connectors.

      The power supply is under the fan shown in the lower right of this overview of the 386 PC:


      I've also posted this at Compaq Deskpro 386/25M Power Supply

      Thanks everyone!  I'm really enjoying this community.