zener diodes

[kardenm]

Can anyone tell me? Is there a way to test (check) a Zener diode??

[MonMotha]

The "diode check" setting on most digital meters can usually be used.  Should read ~0.7V with the red lead on the anode and black lead on the cathode, and it should read approximately the rated zener voltage (maybe a little lower) the other way.

[kardenm]

Thanks. How can I tell what the rated zener voltage should be? Which end is cathode or anode?  Mine tests 0.00 volts in both direction on the diode check setting.  I guess that means it is bad??

[kardenm]

It's a "7.5BM" (from schematic), a 7.5v zener diode. I guess that means it should reab 7.5v in the other direction.?

[MonMotha]

Zener voltage rating is the primary rating of the part.  "7.5BM" sounds like probably a 7.5V zener, yes.  The end with the stripe is the cathode.

If you're reading 0V in both directions, it's probably failed shorted.

[kardenm]

Thank you MonMotha.