Tube Amps / Music Electronics
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|3/4/2006 9:16 PM|
|John D||Blue Voodoo basically dead|
I just bought a Crate BV120H as a project. I thought the problem would simply be a socket problem as that seems common. I should get a schematic probably Mon. or Tue. Right now all that works are the lights for power and standby. There is not even a hum coming out of the system.
The basic problem is no heater at any tube. I've tested where the PT connects to the PCB board and I get 6.95VAC but I get nothing at pins 9,4&5 of the 12ax7 tubes or 2&7 of the 6L6( I assume the pin outs are basically the same as EL34s ). Shouldn't it be just 2 parallel circuits with no other components that goes to the filaments? I can't trace the etchings from the bottom side of the board but I don't see any obvious cracks. Any ideas?
Secondly I wonder about the B+ voltage. On the 2 other heads I've worked on, they had a much lower voltage in the pre amp section. I read 494V at the power tubes and the same at pins 1&6 of the preamp tubes. Is that normal?
Last, how in the hell do you get the PCB board out. It is fairly tight to both sides of the chassis and on both sides it has pots and jacks soldered underneath and protruding through the chassis. Do you have to bend the chassis?
Thanks a bunch, John
|John D Now I've really gotten myself confu... -- 3/4/2006 11:38 PM|
j.vegas sorry to here about your BV120H.i h... -- 3/7/2006 3:18 PM