Testing in circuit can be a bit hit and miss as you often read whats in parallel to the transistor.
I never use the Clay test for these.. makes no sense.
Basically, the transistor only allows current flow in one direction... if you have a general understanding of how they operate then it all makes sense somewhat.
A small current is applied to BASE to "turn" the transistor on. This allows current to flow between Collector and Emitter.. Base acts like a gate that you open and close.
To test... put the DMM onto high Ohms and put the RED lead onto Base and BLACK onto either Collector or Emitter.. you should get a LOW Ohms reading... now switch your leads and you should get a HIGH Ohms reading. If you get this then this "gate(s)" is OK.
Now do the same for Emitter to Collector.. if you get low ohms, its stuffed and gone short between these 2.
If found faulty then remove and test again out of circuit to verify 100%
I actually find it easier with an analogue meter as you can watch the sweep of the needle instead of reading numbers...big sweep means high Ohms..small sweep means Low.
Can determine a transistors function in 10 secs flat this way
