Hi all, Can anyone help me, i need to test a tip3055 in circuit of a power supply i dont know if it is working. I have an el cheapo vom. how do i go about this thanks for any help

 

You have to remove the 3055 or at least disconnect two of the three pins from the circuit in order to perform simple resistance checks.

 

In circuit? As in, without removing it from the PCB?

 

Put some reasonable amount of load resistor on the power supply. 10% of its ability will work. Measure from ground or common to the collector to see if you have main voltage available. Next measure ground to base to see if a drive voltage is present. Finally measure ground to emitter to see if its voltage is about .5 to .7 volts less than the base voltage.

 

Thanks to all i thinki have it now