ADJUSTING OUTPUT TUBE BIAS
Biasing the amplifier is a simple procedure that can readily be done by the owner.
Only a screwdriver is required. After replacing the tubes, the amplifier should be
connected to a load (your loudspeakers will work fine) and there should be no signal
applied to the amp. It should be connected to your preamplifier with the volume
control fully down. Turn amplifier on. After about one minute, turn each of the eight
screwdriver adjustable controls counterclockwise until the associated indicator LED
just goes off. Clockwise rotation may be necessary first to turn the LED on; do not
turn the adjusting screw any farther in the clockwise direction once the LED has
come on.
After the amplifier has warmed up for thirty minutes, the procedure just described
should be repeated. NOTE: It is normal for these LEDs to flash or flicker when the
amplifier is in use. This is normal and no cause for alarm.
This biasing procedure should be performed whenever the amplifier's output tubes
are replaced and also after each six months of average use.
Fuse:
The AC line is fused to protect the power transformer. This fuse will not fail in
normal operation. Failure of the fuse is a symptom of a more serious problem, so the
unit should be taken to a qualified service center. IN NO EVENT SHOULD THE
FUSE BE REPLACED WITH A FUSE OF DIFFERENT TYPE OR RATING
THAN THAT SUPPLIED BY THE FACTORY.
The power supplies to the output stages are fused to prevent damage to the amplifier
in the event of failure of an output tube. When one of these fuses opens the
corresponding channel will be dead. An LED adjacent to the fuseholder will light to
indicate a blown fuse.
Fuses: ac line - 10 amp slow blow
output stage - KTK2 (2 amp fast blow)
