With a Digital multimeter checking of NPN transistor is easy and as follows:
Set the meter to a diode check. And put the +ive lead on the base of the transistor and -ive on the emitter, it should show for a good transistor a drop between 0.4V to 0.8V and put the -ive lead on collector, same should show. (only difference with minor voltage say B-E=0.560V then B-C=0.540V). If you reverse the leads then no drop should be displayed for a good transistor. And also check C-E leads, it is also not show any drop if transistor is good (provided there is no diode internally connected between C and E).
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