Testing a transistor...

[The Buddha]

Ok simple question... how to... there is a good one and a bad one... presumably in the board... they all read the same resistance between the collector, base and emitter. So does that mean somehting else is the problem??
Cool.
Srinath.

[Wrencher]

This site has some decent info on testing procedures.
http://www.tpub.com/neets/book7/25h.htm

On some multimeters (like mine) there is a socket for testing PNP and NPN transistors. The only problem is you need to know what the transistor is and its range or at best the readings will be meaningless, at worst the tester will fry the transistor.

[JeffD]

How much time you got on your hands?

resistance wont tell you much,  but if you tested conductance it should conduct one way but not the other. (select the one that beeps when you touch the test leads together)  if it beeps you have the red test lead on a P material and black on an N material,  But if it beeps all the time its toast.


your going to have to remove the transistors from the circuit no matter what.

Like you know theres 3 leads,  EBC  

so find out the part number that is stamped on it.
go to www.digikey.com and put in that part number and look up the specsheet for the pinouts.

Your multimeter should be able to test diodes.

PNP   NPN
EBC  EBC


so for a PNP transistor it should look like a pn diode from E to B, an NP diode from B to C,  and vice versa for a NPN.

Clear as mud?