Sunn 021-3303, Instruction Manual, Page: 7 / 28

L. V7 & V9 TROUBLE - When this LED glows green, the
tubes at the V7 and V9 locations are operating properly.
When the LED glows red, this indicates a tube failure has
blown the V7,V9 fuse located on the top surface of the chas-
sis. If this fuse blows, replace it ONLY with one of the same
type and rating. 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 volt-
meter.
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 - When the LED glows green, the
tubes at the V8 and V10 locations are operating properly.
When the LED glows red, this indicates a tube failure 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. 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 in
the ON position and the ARENA/CLUB switch in
the Arena position.
2. Remove the bias controls cover box.
3. With a digital voltmeter set to its most sensitive DC volt-
age 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 neces-
sary. 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
FA I L U R E T O R E P L A C E TUBES (See Tube Replacement
Section on the preceding page).
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TYPE PR 344
PART NUMBERS 021-3303 (120V, 60 Hz) US, 021-3343 (230V, 50 Hz) UK,
021-3363 (230V, 50 Hz) Eur, 021-3333 (240V, 50 Hz) Aust,
021-3373 (100V, 50/60Hz) Jpn
POWER REQUIREMENT 360W
POWER OUTPUT 120W RMS, arena / 29W RMS, club, 1kHz sine into 8
Ω
@ 5% THD, (presence @ “1”)
INPUT IMPEDANCE 1 M
Ω
TUBES Four 6L6GC tubes (part# 053980), Two 12AX7A tubes (part #023572),
Four 12AX7WA tubes (part #013341)
FUSE T4A 250V fuse 100V and 120V versions
T2A 250V fuse for 230V and 240V versions
SPEAKER Designed for use with Sunn 412 Loudspeaker Enclosures
FOOTSWITCH 2 button, channel and effects loop switching (part# 053584)
DIMENSIONS Height: 10.2 in. (25.9 cm)
Width: 24.5 in. (62.2 cm)
Depth: 11.6 in. (29.5 cm)
WEIGHT 45 lbs. (20.3 kg)
Product specifications are subject to change without notice.