Help with Inverter Circuit Board Diodes (Picture)

Thread Starter


Joined Mar 1, 2017
Today I am working on an inverter board and trying to determine the problem.
I have tested all the MOSFETS and found them all to be ok.

In fact, the only problem I can find with the board appears to be diode related.
The problem is that it will not power up and presents a short across the fuse terminals.

There are a number of 1N4148 diodes that give odd readings. In one direction of the diode test with my VOM they read approx half a volt.
in the opposite direction nearly 1.5 volts. Since it shows voltage in both directions I assume they are bad.

I removed one of the diodes as shown below.

Is my assumption correct?

Thank you



Joined Mar 10, 2019
You can only measure the diodes when they are removed from the circuit. How did that 1N4148 test after you removed it?
A 1N4148 is a small diode, and would blow if any amount of power was applied to a bad diode of that type. Another possible cause is a shorted MOV (surge protector). Something similar to that blue thing next to D13