Post by c***@gmail.comI hope you’re wrong about that
OK...
First, don't *ever* plug the amp's output
into anything besides a speaker or a "power
brake" or other attenuator device. Tube amps
need to be correctly loaded, or the power tubes
(and the sockets they are plugged into) can
wind up frying. Second, WTF is an "oregano"
tube? Is that some kind of recently-coined
slang? Correct terminology is essential for
electronics; technicians may indeed use jargon,
but only when speaking to each other. If you
want to be understood, use the right words.
So.
You say you can hear a hum when you take the
amp off standby - does this hum come from
the speakers, or is it mechanical? (You can
find out by listening to the hum as you unplug
the amp's speaker wire from the output jack;
if the hum doesn't stop when you do this, it's
mechanical - probably due to transformer lamination
buzz. If the hum does stop, that means your speakers
are at least marginally functional, and not likely
to be causing your problem. Make sure to check the
speaker wiring for loose connections.
Here's how you proceed from this point: you need
a couple of spare tubes - one 12AX7 and one 12AT7.
Take the upper back off the amp so you can reach
the preamp tubes more easily. Remove all of the
shield cans from the preamp tubes. Starting with V1,
which is the first tube on the RIGHT when viewing
the amp from the REAR, begin subbing the tubes one
by one - but before you do this, plug your guitar
into the NORMAL channel and see if you have sound.
If you do, that probably means the tube in the
ViBRATO channel is a goner. If you don't have sound
with your axe plugged into the NORMAL channel, move
the cable over to the VIBRATO channel. Still no sound?
If this is the case, that means the problem is more
than likely downstream from the preamp. Try subbing
a 12AT7 into the V6 socket - that's the one directly
next to the power tubes. (Remember to put the amp on
standby before removing or installing any tubes.) If
the amp works now, you've found the problem: bad driver
tube. Leave the new 12AT7 in that hole and you're done.
If not, sub the rest of the tubes one by one. If you
get sound when subbing a tube, that socket had a bad
one in it and that was your problem. V3 and V6 are
12AT7s; all the rest are 12AX7s. If you get the order
mixed up it's not going to hurt anything besides your
feelings - the amp will sound like ass. Check the tube
position chart for details.
Anything else besides cables, speaker wiring inspection
and tube-subbing is going to require test equipment and
someone who knows how to use it.
Lord Valve, ThD
Expert (fuck you)