I have a power amp circuit with mosfet output transistors. The amp was damaged by dropping it. The amp blows fuses and the power transformer is fine. Do I check these transistors or do they normally fail open circuit?
My experience with Mos-Fets is they are difficult to test with just a meter. Its better to put them in a simple test circuit and vary the gate voltage to see if they behave as they should.
Different types of Mos-Fets require different biasing but basically changing the bias voltage should change the current through the device.
There should be virtually ZERO gate current.
Different types of Mos-Fets require different biasing but basically changing the bias voltage should change the current through the device.
There should be virtually ZERO gate current.
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If an amplifier has been dropped, the first call would be to carefully check all connections for broken solder joints.
Failure mode is almost always a near or total short for common vertical power fets.
Use a bulb tester and fault find in the normal way.
Use a bulb tester and fault find in the normal way.
If you can achieve zero D-S current with G bias then they might be OK
If you can identify the MOS-FETs then we can be more specific as to how to test them.
If you can identify the MOS-FETs then we can be more specific as to how to test them.
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The FETs dont fail from a drop. More likely u have a short somewhere in the voltage supply circuit.
You probably have a cracked circuit board or trace. Mosfets usually fail shorted from over voltage, over heating ( excess current ) or excessive gate voltage. I have rarely seen them measure open unless their plastic covering had exploded due to the initial short.
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