Crunch class D

[Perry Babin]

Which transistor?

 

[Hexhclass]

Q21 one the PS driver board.It directly connected to pin one of the output driver board ,from there it goes through two resistors to reach Base of Q1.

 

[Perry Babin]

How many header pins do you have on the PS driver board?

 

[Hexhclass]

14 pins
Largest transistor Q21.

Are all these part of the over current protection?

pic is a similar amp i work on years ago but same.

 

[Perry Babin]

Does the relay engage?

 

[Hexhclass]

Yes

 

[Perry Babin]

With a speaker connected and oscillation, does it produce normal audio with no DC offset?

 

[Hexhclass]

It plays good audio no DC offset

 

[Perry Babin]

Post a photo of the other side of the PS driver board (if there are components on the other side).

 

[Hexhclass]

.

 

[Perry Babin]

It might have some similarity to the following. It may help.

I think you're going to have to use a combination of component checking and process of elimination to track down the faulty part.