Name:    Terry
Email:   musicmanamp@yahoo.com  
Subject: Noisy 212-HD One Fifty
Thread:  291
Time:    Sat, 1 Dec 2001 01:16:48 UTC

Well Chris You are going to have to pop the hood!
#1 If it is a OP-Amp 1458 That would be a cheap fix. Move the three you have and see if makes a difference.
#2 Have you checked the bias 25MV DC across the 3.9 OHM emitter Resistors amp on high power, no signal.Will Email you bulletin if you need it may help!
#3 Check the wires from master pot to board or the pot could be bad.
#4 It could be one of the .1/100volt disk capacitors or 25/400 or 50/150 or one of the other capacitors.