Spotting sneaky reverse leakage in diodes

[Alan]

You’ve got a board in front of you, and while those diodes might look good at first, you’re aware that a small leak can ruin the whole circuit. What quick meter tricks or straightforward tests do you use to identify reverse leakage before it becomes a problem?

 

[soldersoldier]

When you set your multimeter to diode mode, you should see about a 0.6V drop for silicon diodes. If you flip the leads and get a reading, that diode’s shot. It's a quick and reliable test.

 

[TheOhmBreaker]

I use the diode test feature and switch the leads. A good diode will let current flow one way and block it the other. If it doesn't, it’s definitely bad. It takes just a few seconds to check.

 

[theOhmcoder]

Testing diodes in-circuit can be a bit tricky due to other pathways, so I usually lift one leg if I'm unsure. After that, I just check both directions. A leaky diode will show resistance both ways, which isn’t right.

 

[Currentaffair]

For any minor leakage issues, check the reverse resistance using the highest ohm setting. It should be in the megohms or show as infinite. If it’s below 100k ohms in reverse, that's a red flag. You can also gently heat the diode with a soldering iron; this often exacerbates leakage and helps reveal diodes that are close to failing.