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HP-43120A defibrillator PS

Discussion in 'Electronic Repair' started by [email protected], Feb 17, 2007.

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  1. Guest

    I'm looking for the schematic of this medical instrument or even only
    the schematic of its power supply board (HP 43100).
    The switching mosfet is arcing between drain and source until a
    resistor fuses on the 220V AC line (usually a couple of zeners around
    the mosfet driver BJT go short too). I checked the snubber part of the
    circuit and it tests ok. The schematic would tell me if arcing
    interrupted one or more hidden traces around the mosfet circuit.
    D-S arcing sounds like no current recirculation, doesn't it?
    Thanks in advance

  2. Guest

    A common failure on that supply is high esr capacitors. Beyond that,
    you cannot get any component level information on it.
    You won't get the schematic, it was board level replacement repair and
    HP never released them.
  3. Guest

    Thanks for info, I failed to mention that I also checked ESR of all
    electrolitics. The big ones are well below 0.5 ohm and the tiny axial
    33 uF ones are below 2 ohm. It doesn't seem an ESR problem,
    unfortunately. But I'll recheck all just in case.

  4. Franc Zabkar

    Franc Zabkar Guest

    I'd replace the relevant components anyway. I recently repaired a
    timing light where a faulty HV (pulse rated?) ceramic cap tested OK
    out of circuit but behaved as if it was OC in-circuit.
    - Franc Zabkar
  5. This is a medicial lifesaving device to be used to restart a stopped

    As a retired biomed engineer I would not attempt a repair with no
    documentation available.

    Way too much lialibility involved and you want them to work everytime
    100 percent.

    Board replacement is probably best.

    And yes I have had them used on me once. Still glad it worked.
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