Performer/Roc-pro transformer

[J M Fahey]

Why do you think so?

Thousands of RocPro/Performer amps happily out there with the exact same heat sink assemblies (typically somne thick aluminum spreading heat on the whole aluminum panel) .

You have dead transistors, no doubt, but something else killed them.

A common mistake is to unbolt transistors from the heat sink assembly and turn amp on "just for a minute" , "just to check that everything is fine".

That test is usually one minute too long to kill outputs.

Annoying as it seems, board must be pulled to replace suspects, but then must be fully greased and mounted to test.

If you need to repeat everything because some problem remains, so be it

[Enzo]

What Juan said^^^^

You are assuming the output failed because of the heat sink without any evidence to support that.   Thousands and thousands of those amps are out there and not blowing up.  They use the same chassis/sink design on a number of other models too.  Lots of things cause transistor failure.  Heat can certainly be one of them, but not the only one.

[g1]

  Some of those Fenders use the heatsink "bar" that mounts to the chassis.  From what I recall, it can be mounted upside down and if so, doesn't mate correctly to the chassis.  Or there can be dried up heatsink compound that interferes with proper heat transfer.

[Enzo]

You may be right.  I have reassembled them wrong then been ticked off that I had to take it apart because it didn't fit.  But I don't recall being able to leave it in wrong, some part of it was in the way.  The main headache was I was going to have to get MORE grease on my fingers to turn it over.

[DrGonz78]

Yeah I got in a habit of drawing an arrow with a black sharpie on the side of the heat sink bar to make it easier to put it back together correctly the first time. I have an old Roc Pro 700 sitting in the shop and mine gets pretty hot. I have been meaning to pull it out and check the bias etc. The amp is in such crap condition that I forgot about it for a while now. I will have to give a good look over soon.