Help with Inverter Circuit Board Diodes (Picture)

Thread Starter

Lumenosity

Joined Mar 1, 2017
612
Hello,
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

1N4148_Diode.jpg
 

sagor

Joined Mar 10, 2019
479
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
 
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