Mains Fuse
-
"
blowing
"
:
Unplug amplifier from the wall AC.
Remove the power tubes
(see precautions section)
. Install a
new
2
Amp
"
slow blow
"
fuse
(1 Amp "slow blow" 240V)
.
Plug into the wall AC and turn the amp
on
(with
no
power tubes in the sockets)
.
Should the mains fuse continue to "blow", your amp will need to be serviced.
If the fuse
does
not
"
blow
"
, and the amp lights up, turn amp off, and install a
new
set of matched EL84 power
tubes. Turn the amp back on. If the fuse does not blow, play the amp and monitor.
Amp Lights Up
-
No Sound
:
Check the speaker connection at back of amp and at the input of the speaker cabinet. Bypass all
pedals and effects and plug your guitar into only the amplifier. Check the guitar cable and / or
try another guitar.
Check the power and the pre amp tubes and make sure that they are installed correctly and that
the filaments within each tube are lit.
Note
:
sometimes audio tubes can look operational
- (with
the filaments lit) -
but be defective in not passing signal. This is rare, but can occur.
Check / test / replace - the
H
.
T
.
fuse for continuity with a digital Ohm meter. It may be blown.
Amp is making a
"
Humming
"
,
"
Hissing
"
,
"
Feedback
"
or
"
Crackling
"
-
sound
:
This is most likely a bad pre amp tube. Pre amp tubes can develop problems over their life span.
They may be operating flawlessly, and they may also test fine on a tube tester, but for what
appears like for no reason, can suddenly begin to make a
"
hissing
"
or a
"
crackling
"
sound. They
can begin to feedback or have microphonic or
"
ringing
"
symptoms.
(See previous section titled:
ECC 83, 12AX7, 7025, and CV4004)
, or develop
filament
"
humming
"
- which is a low
background hum, often mistaken for a problematic filter cap. Filament
"
humming
"
is much
more common with new, modern available pre amp tubes. Unfortunately, you will most likely
have to replace one of more of your pre amp tubes with any of these problems. This is another
reason we stress purchasing n.o.s. tubes - they are less likely to
"
go bad
"
.
Fluorescent and neon lights, rheostat wall dimmers, and some appliances may cause your amp
to contain a
"
hum
"
or
"
buzz
"
sound. An internally shorted guitar cable or using a speaker cable
for a guitar cable can also create a
"
buzz
"
sound through your amp.
Over time, the input jack may occasionally make a
"
crackle
"
sound when you extract your
instrument cable from the front panel of your amp. This is usually due to a dust / contaminate
build up on the input jack’s ground shunt. This would require that the inside of the input jack be
cleaned professionally. We recommend using
DeoxIT
®
Gold
G5.
Copyright 1999-2017, Komet
Amplification. Group, L.L.C. May not be reproduced in any form without express written consent from Komet
Amplification.
