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checking transistor using digital MM.
1: select diode check range
2: fix one lead of DMM (say +ve red lead) with right most terminal of transistor
3: connnect -ve lead (black) of DMM with centre terminal.
4: if DMM show any reading then u have find one PN junction.note that reading.
5: now connect -ve lead with 3rd terminal of transistor.
6: if this also show any reading it means u have found 2nd junction also .note reading of this junction also .
7: the terminal where u connect +ve lead is the base of transistor. and other two terminals middle and left most terminal is collector and emiiter.
8: now u have to differentiate between collector and emiiter.
9: base-emiiter junction has slighlt more resistance then collector.
10: the terminal which has high value is emiiter and other one is collector.
11: if line 6 is not true then fix +ve lead of DMM with middle terminal and check other two terminal with -ve lead. if DMM shows reading with both terminals then follow line8,910..
12: if middle terminal show reading with one terminal and dont show with other terminal then fix +ve lead with 3rd terminal of transistor and repea process.
13: if +ve lead dosent give u any result then repeat this process by -ve lead of DMM.
In Metal can types, the pins are arranged circularly. Just see a Tab in the rim. In NPN type, the pin close to the Tab is Emitter, the opposite one ,the Collector and the middle one, base. In PNP type the pins are reversed. Pin close to the Tab is Collector.
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