[TechAssist] Re: Power MOSFET - Huge Flash
- From: becyn <becyn@xxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Fri, 29 Jul 2005 11:18:03 -0400
bad transformer?, possibly bad drive circuitry (railed high).?
I beleive that chassis has a driver IC. If so, run it without the fet.
you should see a burst of pulses when ac is applied, then shutdown to a
zero volt condition at the gate drive.
Jim McVey
McVey Alltronix
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Newburgh N.Y. 12550
"If it doesn't play...
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Bil Green wrote:
>I replaced a shorted MOSFET (driver in SMPS) and other parts
>(listed below) and as soon as the set was plugged in there was a
>huge flash (arcing) observed at the MOSFET and it shorted
>immediately.
>
>There is carbon between the metal clip and the plastic front (not
>the backside, and there is no crack visible in the plastic) of
>the MOSFET. I don't want to power it up again until I have a clue
>as to what is likely causing this (the original one didn't do
>this).
>
>I did use a TDA4605-2 (instead of -3) for U14101, and I can't
>imagine this caused enough voltage (thousands?) to create this
>large arc.
>
>With less AC voltage the set probably won't start so I rather not
>use this method.
>
>RCA PTV
>model P61929
>chassis PTK195ST
>
>Q101 (MOSFET) shorted
>U14101 melted
>R14125 burned
>
>Replaced 3 other resistors as recommended (checked OK)
>
>Bil
>
>PC 1000
>M-Pulse 5000 magnetic pulse generator
>http://magpulser.com
>Mammoth Lakes, CA
>760-924-1000
>
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