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HP-43120A defibrillator PS

Hello, 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

Francesco

Reply to
francesco.messineo
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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.

Reply to
dkuhajda

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.

Francesco

Reply to
francesco.messineo

On 17 Feb 2007 05:09:49 -0800, snipped-for-privacy@gmail.com put finger to keyboard and composed:

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

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Please remove one 'i' from my address when replying by email.
Reply to
Franc Zabkar

This is a medicial lifesaving device to be used to restart a stopped heart.

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.

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

Reply to
Hugh Prescott

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