I was looking at the back of my Peavey 260 head; I need to replace the power cord, as it has seen better days, & I noticed that there is a white residue around the output transistors, or at least around the plastic cap. Anyone ever seen anything like this?
Maybe it isn't anything from the transistors themselves, but just a "gunk" from lack of cleaning, etc. It just made me suspicious..
And then I came across this from another site;
This is because
an electrochemical reaction takes place when electrical currents flow through a junction of
dissimilar metals. The result of this reaction would be the creation of a white, powdery
residue that actually inhibits electrical flow. By using brass, with its high copper content, we
avoid the build-up of this residue and the resulting deterioration of performance...
Think that may be it?
And, my second question; The transistors are RCA 62792 (4 of them, discontinued) I see it crosses over to a 2N3055, readily available, cheap price. Should I go ahead & replace these now before I notice any trouble? What kind of job is this? How involved?
Sorry to say I have never replaced any of these! Gotta start somewhere, I guess. :oops:
It is probably thermal grease, which is used to improve heat transfer from high power components like power transistors.
Does it look a bit like this or this?
The white stuff in those pictures is the thermal grease.
Being grease, it may have collected a bit of dust over the years (or partially dried out), making it look powdery.
If that's it, nothing to worry about.
And, I've never seen transistors leak anything (other than smoke). Generally transistors don't go bad slowly. If they go bad, they do it all at once, sometimes spectacularly.
I wrapped a newspaper ’round my head
So I looked like I was deep
If everything works, why not just spray them and brush it off with a small paintbrush, or spray with silicone?
Like a bird on the wire,
like a drunk in a midnight choir
I have tried in my way to be free.
Kent - It does look like the pics. Guess that must be what it is.
Blue Jay - I haven't used the amp in awhile. I was thinking that maybe the white residue was a sign that something was wrong with it.
Guess I will just replace the power cord & try things out.
Thanks guys! :)
