Fender bandmaster reissue r69 keeps burning up

[Corben]

Anybody come up against this. Its the voltage tap for the preamp tube plates i believe. The resistor smokes with out any tubes in the sockets. I checked to see if the tube sockets had any shorts in them couldn't find anything. Checked to see if maybe the jumpers shorted to traces underneath them, found nothing. I checked the filter cap for capacitance, esr, and dc Resistance. it tasted normal. Thinking about running the filter caps and coupling caps on my sprague high voltage cap tester. or maybe it just be easier to pop in new coupling caps.
Thanks for any help guys.

[stokes]

If you are talking about the dropping resistor in the B+ rail and it is cooking with no tubes the most likely cause would be a leaking filter cap,the one after this resistor.Just disconnect it and see if the resistor stops cooking,it should.I would suggest changing all the filter caps in that amp.I've seen too many problems in newer Fenders lately caused by the crap caps they use these days.

[Corben]

yeah i guess theres no definitive test for filter caps. i tired ac and dc resistance, and a capacitor meter it tested good on all that. hope thats it ill see if i haveanother 22uf 500volt anywhere

[Mark Black]

Does that version have reverb? (I couldn't find any info or schematic on "Bandmaster Reissue").

If so a reverb driver transformer shorted to ground could be another possibility...

[Enzo]

It has a reverb, but it is the DSP kind. It is a largely solid state amp/hybrid, the VM series. Schematic below.

If R69 burns up then C38 is instantly suspect. The cap is operating at 400v. The volt or two from your ohm meter will not tell you if the cap gets super leaky at anything over say 10 volts. And your typical cap meter, same story. It may well work as a perfectly good 22uf cap at 2 volts, but at 400 it could be a different story.

A simple test, unsolder one end of C38 and lift it from the board. Power up without tubes. Still blows fuses? If so, then the cap was not the problem, if the fuse now holds, the cap is the bad boy.

[kounta]

same problem

hi there, i have the same problem , change c39,c38,c37,c46 and it's always the same r69 burn !!! can you help me ??

[52 Bill]

hi there, i have the same problem , change c39,c38,c37,c46 and it's always the same r69 burn !!! can you help me ??

Welcome. Have you tried new output tubes? Just pull them out and see if the resistor stops burning.