I have a customer in here with a Sunn 1200S tube amp head. It is huge – with (2)GZ34s as rectifiers and (4)6550 outputs. This one has tremolo and reverb - I mention this because some of them don't. It appears to be ultra linear outputs as well.
Anyhow I am pretty sure the power tranny is bad. It came in missing one rectifier and a fuse. I brought it up slowly with a variac and as the power gets all the way up the tranny would vibrate/buzz a bit and after a few moments (not immediately) the amp meter on the variac pegged and it blew the fuse. I tried this with just the rectifiers in the circuit (I disconnected the heaters as well as with it on standby) and it did the same buzz (not through the speakers but the power transformer) – and I shut it down before it popped the fuse. Without the rectifiers it is fine. The rectifiers test good (one is new) and the sockets don’t appear to be torched.
Where and how much to get a replacement for the power tranny? How much to get it repaired?
Any advice here? I hate to tell the customer it is not worth repairing I am trying to determine if we are fixing this amp or not.
Thanks.
John.
