Roar Quad 15, Руководство пользователя

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10. T
UBE REPLACEMENT
& B
IAS ADJUSTMENT
Warning! RISK OF ELECTRIC SHOCK! Service and replacement of tubes shall be performed by qualified service
personnel only!
10.1 P
OWER TUBE REPLACEMENT
The rear panel of the Quad15 is equipped with a small cover that can be removed to replace the two 6V6 power tubes.
A stereo jack socket is placed between the tube sockets for easy access to measure bias current for the power tubes,
which is done by adjusting the trimmer placed above the bias jack socket. (Small screw driver required).
1. Pull out mains chord and wait for 1
minute.
2. Remove rear cover. (4mm allen key)
3. Turn the bias trimmer all the way
down (anti-clockwise).
4. Replace power tubes with new 6V6
tubes.
5. Connect a mono jack cable to the
socket between the power tubes.
Plug the jack in all the way to
measure left power tube V6. Pull
the jack half way out to measure
the right power tube V7.
Alternatively
use a stereo cable or make your own bias test
cable. Tip: V6, Ring: V7. Sleeve: Ground.
6. Turn on power.
7. Measure voltage on the jack cable
between tip to sleeve and ring to
sleeve. 1mV corresponds to 1mA.
8. Turn up the bias trimmer until the
bias voltage reaches ~ 25 to 30 mV.
After a couple of minutes, check
that both power tubes
read ~ 25 to 30 mV.
Note: If the meter reads more than 30 mV despite the bias trimmer is
turned all the way down (anti-clocklwise), turn off power immediately.
The Quad15 is primarily designed for modern 6V6 types of power tubes which typically allows
an absolute maximum plate dissipation of 14 watts. Some types of 6V6 tubes might have
lower plate dissipation ratings, where lower bias current is recommended. (6V6 tubes with
maximum plate dissipation of 12W or lower, recommended bias current is ~ 25 mA).
Unlike other tube amplifiers, the Quad15 is equipped with a short-circuit proof power supply
that prevents faulty power tubes from damaging the circuit and blow fuses. If a tube shorts,
the HV supply will go into current limiting mode, protecting the amp and be ready to accept
a new set of tubes without replacing a fuse. Quick and easy, ready for touring.
10.2 P
REAMP TUBE REPLACEMENT
The Quad15 is equipped with the following preamp tubes:
Preamp tube Type Placement Function
V1 ECC83 / 12AX7 Preamp board near input jack All channels
V2 ECC83 / 12AX7 Preamp board mid position Overdrive, Rhythm & Lead
V3 5751 Preamp board Rhythm & Lead channel
V4 ECC81 / 12AT7 Rear chamber Effect loop
V5 ECC83 / 12AX7 Rear chamber Phase inverter
V1, V2 and V3 is placed on the preamp circuit board. Here it is necessary to remove the Quad15 out of the
Rackcombo/Head/Rack and remove the top cover using a Philips head screwdriver.
1. Pull out mains chord and wait for 1 minute.
2. Remove top cover. (Philips head screwdriver)
3. Replace preamp tubes. Make sure to mount the tube retainer correct.
4. Mount top cover before plugging in the mains
Adjust bias trimmer with screwdriver