Yellow dust in 70s Twin Reverb

[ToddRV]

A customer brought in an older Fender Twin Reverb for repair. Complaint is blows fuses. When I was removing the chassis from the cabinet, I noticed this yellow dust all over the tubes and tube covers and the chasis and transformers. This stuff is nasty and burns the eyes and nose. I thought fist of a blowed up cap, but the dust was not under the cover for the filter and high voltage caps. All the other caps appear visually ok , but I have not tested all of them yet. Any ideas what this stuff is and where did it come from? Is it related to the fuse blowing? The fuse blows a few minutes after the standby switch is thown and a low level signal is sent to the input.

Thanks for your responses
ToddRV

[Enzo]

Can't imagine it is involvd in teh amp problems.

That stuff is common, it is the metal finish on teh chassis breaking down over time. If I am not mistaken the finish is galvanized and this crap is zinc oxide. In my experience it doesn't cause trouble other than hurting your eyes if you rub them.