Noise - HK Sound House 600

[dhaman]

Hello, I have this PA system on the table. I'm working on hi-fi mostly this is first PA system.

ISSUE: There is huge noise on tweeter even if volume is down.

I'm trying to do something with power amp.
I added 22pF parallel to R27. but it not helps.

Do you have any idea what can be upgrade to do low noise ? Thank you for any ideas.

Schematics of poweramps: schematics.png
Service manual: hughes_kettner_lucas_600_service_manual.pdf

 

[MAAC0]

What kind of noise ?

 

[rayma]

There is huge noise on tweeter even if volume is down.

Make sure the output Zobel resistors are ok, and not burned up.