Planet Audio BB2400.1

[mnhiphop101]

The high side fets are heating up. The waves between high and low side are slightly different. The yellow trace is the high side.

 

[Perry Babin]

What terminals were these taken from?

 

[mnhiphop101]

I have 1 fet per bank in. The measurements were taken from an empty fet location.

 

[Perry Babin]

Gates, drains, sources?

On which FET location?

 

[mnhiphop101]

Hs gate
Ls drain
Is there switching on more than 1 of the legs?

 

[Perry Babin]

The HS gate is going to be very different from the HS source and the LS drain (which are directly connected).

 

[mnhiphop101]

So is there a problem with those switch waves?

 

[Perry Babin]

I don't really see anything wrong but the high-side driver waveform would be more definitive if you measured it in differential mode. As is, it's riding on top of the rail-rail signal so there isn't enough resolution to see any detail.

 

[mnhiphop101]

So I just pulled the fets and I'm getting switching on the gate and source on both the high and low side. I'm pretty sure that's not normal. Is it?

 

[Perry Babin]

Is your scope still floating?

The low-side source is directly connected to ground.

 

[mnhiphop101]

I used my battery powered scope

 

[mnhiphop101]

It's been over a year since I've worked on an amp so I'm a little rusty.

 

[mnhiphop101]

Sorry I mean when I probe the gate and source on both high and low side I get signal

 

[Perry Babin]

When you probe the low-side source, where is the ground for your scope?

The low-side source is directly connected to ground. <<< This is wrong. It's tied to the negative rail. I had this thread and the JL thread mixed.

 

[mnhiphop101]

The amp seems to be working fine now. Although it was behaving in a way I've never seen before. If I didn't have an equal amount of fets in each bank it would draw excessive current. With an equal amount it runs fine. Super weird.