8
L. V7 & V9 TROUBLE - This LED indicates tube failure
or trouble at the V7 or V9 tube locations. When the
LED glows green, the tubes are operating properly.
When the LED glows red, this indicates a tube failure
which has blown the V7,V9 fuse located on the top
surface of the chassis. If this fuse blows, replace it
only with one of the same type and rating. NEVER
use a fuse with a higher current rating as this could
damage the equipment and present a serious
safety hazard. Next, replace the tubes in locations
V7&V9, check and adjust the bias and balance. If the
amplifier repeatedly blows fuses, it should be taken to
an authorized Fender service center.
M. BIAS - This trim adjustment is used in conjunction
with the BALANCE (item O) and the bias test points
(items N) to set the output tube bias.
N. GND, V7&V8, V9&V10 - These are bias test points
used to measure output tube bias and balance with
a digital voltmeter.
O. BALANCE - This trim adjustment is used in
conjunction with the bias test points (items N) and the
bias adjustment (item M) to set the bias balance
between the power amp tube sections of your Model T.
P. V8 & V10 TROUBLE - This LED indicates tube failure
or trouble at the V8 or V10 tube locations. When the
LED glows green, the tubes are operating properly.
When the LED glows red, this indicates a tube failure
which has blown the V8,V10 fuse located on the top
surface of the chassis. If this fuse blows, replace it only
with one of the same type and rating. NEVER use a
fuse with a higher current rating as this could
damage the equipment and present a serious
safety hazard. Next, replace the tubes in locations
V8&V10, check and adjust the bias and balance. If the
amplifier repeatedly blows fuses, it should be taken to
an authorized Fender service center.
Output Tube Bias Adjustment Instructions
1. Turn on your Model T and let it warm up for at least two
minutes with the STANDBY switch (item M, page 5) in the
ON position and the ARENA/CLUB (item D, page 6) switch
in the Arena position.
2. Remove the bias controls cover box.
3. With a digital voltmeter set to its most sensitive DC
voltage scale, measure the voltage between the GND and
V7,V8 test points (items N) and adjust the BIAS control
(item M) for a reading of .06 VDC (60 mVDC).
4. Connect the digital voltmeter to the V7,V8 and V9,V10 test
points and adjust the BALANCE control (item O) for 0 VDC.
5. Replace the bias controls cover box.
Notes
1. Make bias and balance adjustments ONLY when
necessary. If you are unsure about setting bias and
balance, take your amp to the nearest authorized Fender
Service Center.
2. For optimum sonic performance, set bias to .06 VDC
then set balance.
3. If the output tubes can not be balanced, check the bias
setting and/or replace the 6L6GC output tubes.
4. The power tube trouble LEDs are NOT indicators of worn
tubes. If your tubes are worn and sound weak the LEDs
may still glow green. The trouble LEDs turn Red only after
tube failure has already occurred. DO NOT WAIT FOR
TUBE FAILURE TO REPLACE TUBES. (See Tube
Replacement Section, page 11).
MODEL T REAR PANEL FUNCTIONS, CON’T
LMNOP
