Power supply issue

[mnhiphop101]

What's causing the wave on 1 of my ps sections to look like this? All the other sections look perfect. The wave going in is perfect.

 

[Perry Babin]

make/model amp?

Drain, gate?

 

[mnhiphop101]

It's a dd m4a.

The signal on the gate looks good
That is the drain

 

[Perry Babin]

What's the resistance from the drain leg/tab of the FET to the B+ terminal?

 

[mnhiphop101]

1 ohm

 

[Perry Babin]

Compare to the sections that are working normally.

 

[mnhiphop101]

They read the same. That's why I'm so baffled. Everything that I've checked is the same

 

[Perry Babin]

Are the source legs all at ground (read 0 ohms to ground) on those FETs?

 

[mnhiphop101]

Yes
also I was wrong when I said there was 1 ohm from drain to B+. its actually a direct short

 

[Perry Babin]

I don't see anything that is could be other than defective FETs if you have a good gate signal on the gate leg, 0 ohms to B+ on the drain and the source legs are 0 ohms to ground. There is a very small chance that the transformer could be defective but that's very unlikely if there is no excessive FET heating.