Hey all,
Can someone tell me how to test power MOSFETs to see if they are damaged?
Old fashioned bipolar transistors, I know how to test. Mosfets? Any experienced troubleshooters\repair folks out there, please chime in with what you think might be helpful. If they are shorted source to drain, that's easy. Gate to drain or source, easy. But if not so obvious, is there something I can do besides desolder and replace to be sure???
I have an unfortunate accident victim - an old Tripath amp - and I am trying to figure out how bad it is and whether it is worth repairing.
Thanks for whatever you can share.
mr coffee
Can someone tell me how to test power MOSFETs to see if they are damaged?
Old fashioned bipolar transistors, I know how to test. Mosfets? Any experienced troubleshooters\repair folks out there, please chime in with what you think might be helpful. If they are shorted source to drain, that's easy. Gate to drain or source, easy. But if not so obvious, is there something I can do besides desolder and replace to be sure???
I have an unfortunate accident victim - an old Tripath amp - and I am trying to figure out how bad it is and whether it is worth repairing.
Thanks for whatever you can share.
mr coffee
67 reads later and no replies... trying to read between the (absent) lines...
So should I assume that if nothing is shorted out, the MOSFET is probably OK???
mr coffee
So should I assume that if nothing is shorted out, the MOSFET is probably OK???
mr coffee
That is a good place to start.
The problem with testing Fets is they all bias at different points. Some, with a DVM, show short circuit for a few seconds after switching the gate on slightly, others don't.
If not short, they are probably not damaged.
The problem with testing Fets is they all bias at different points. Some, with a DVM, show short circuit for a few seconds after switching the gate on slightly, others don't.
If not short, they are probably not damaged.
For integrated FETs you can only judge from the symptoms. If you got full DC at the output while disconnected filter amp draws lot current, the output stage is most likely fried.
Assuming a N-channel FET...
Remove from device, connect source/gate together. Set a DMM to diode test mode and measure in both directions between source/drain. You should see a diode drop from source->drain and open circuit from drain -> source.
Now hook up a 9V battery or bench supply to the FET, positive to gate, negative to source. Drain <-> source should measure 0.0V in both directions with the DMM in diode test mode.
Remove from device, connect source/gate together. Set a DMM to diode test mode and measure in both directions between source/drain. You should see a diode drop from source->drain and open circuit from drain -> source.
Now hook up a 9V battery or bench supply to the FET, positive to gate, negative to source. Drain <-> source should measure 0.0V in both directions with the DMM in diode test mode.
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