MOSFET TESTER
While working on repairs of Computer SMPS I came across a Mosfet in the starter circuit of the power supply and scratched my head on how to test this device and came across this simple setup for testing these devices as shown in the diagram. The meter prods are connected depending on the device whether it is a N-channel or P-channel device. There are two switches used SW1 and SW2 and one Capacitor C1 47nf.
When SW1 is connected to the drain, C1 charges to the supply voltage of the meter
i.e. 3 Volts with the meter in the diode test position, when the SW1 is changed over to the second position the voltage charge on the capacitor is applied to the Gate of the mosfet and the meter shows a reading indicating a good Fet. To discharge the gate voltage Press SW2 which is a push to on switch to short the gate to source and the meter indication will drop to zero Any other indication will show that the device is defective
While working on repairs of Computer SMPS I came across a Mosfet in the starter circuit of the power supply and scratched my head on how to test this device and came across this simple setup for testing these devices as shown in the diagram. The meter prods are connected depending on the device whether it is a N-channel or P-channel device. There are two switches used SW1 and SW2 and one Capacitor C1 47nf.
When SW1 is connected to the drain, C1 charges to the supply voltage of the meter
i.e. 3 Volts with the meter in the diode test position, when the SW1 is changed over to the second position the voltage charge on the capacitor is applied to the Gate of the mosfet and the meter shows a reading indicating a good Fet. To discharge the gate voltage Press SW2 which is a push to on switch to short the gate to source and the meter indication will drop to zero Any other indication will show that the device is defective
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