Schottky Diodes: DMM Test?

[Johnny_Law]

New to Schottky diodes. From reading, I gather they are low-forward-voltage, fast switching diodes, with more reverse leakage than silicon diodes. Forward voltage drop (Vf) should be around 0.35V, and they should block in reverse.

There's a plethora of info online but I haven't come across a straightforward DMM test, explained in simple terms.

I have four suspect Schottky diodes here, out of circuit .... using my DMM's Diode Test function, I measure:

Vf: All four read ~0.07V (red lead on anode, black lead on cathode)
Reverse voltage: Three read 0.5V to 0.9V, one reads OL (black lead on anode, red lead on cathode)

I gather this means they are bad ... yes? Or am I omitting a step?

(References I read before posting, maybe I missed something in these ...)
https://diodnik.com/en/kak-proverit-diod-shottki/
https://forum.allaboutcircuits.com/threads/how-do-i-test-schottky-diodes.168643/
http://www.noahtec.com/schottky-diode.htm
https://forums.ybw.com/index.php?threads/testing-a-schottky-diode.499641/
https://dcaclab.com/blog/how-to-test-a-diode-complete-guide/

 

[jhjove]

If you are correct on your lead connections and meter settings then yes, i'd say these schottky diodes are bad.

FWIW:
I recently was repairing a small 5V @2A plugin switching power supply module. This unit used 2 different schottky modules with a 3 pin form factor (2 diodes per module).
The case was a TO-220 style with the center lead the common connection (cathode) and the other two connections individual anodes.
Using my DMM; forward drops were in the .325V range for both diodes in the one module, the other module measured .190V range for both diodes. Reversed connection was overload reading. So good diodes in my case.

 

[Skywatcher]

I gather this means they are bad ... yes?

Yep, replace them.

 

[petehall347]

try not touching the probes when testing .

 

[gadget73]

thats an odd way to fail. Any time I've had one with near zero volts one way it was the same in the opposite direction. basically the junction shorted and it was like testing a piece of wire.

 

[egellings]

Sounds like they are dead shorted.