V-1250THX subwoofer
page 15
Because the subwoofer easily reproduces 60 Hz signals (the frequency of hum), it is often blamed
for causing hum that originates elsewhere in the system. Always avoid running all speaker wires and
RCA interconnect cables near to AC cords and component power supplies. Placing wires and cables
close to AC lines often results in hum. If necessary, reroute your cables.
To identify the source of hum, remove all input cables to the subwoofer, but leave it plugged into the
AC outlet. Set the "BASS LEVEL" switch to the "VARIABLE" position. Carefully turn the "BASS LEVEL"
control up towards the "MAX" position. If you hear hum from the subwoofer, it is the source of the hum.
If you hear no hum or much less hum, the problem is in another component or a ground loop.
For ground loop problems, when the subwoofer is plugged into a separate AC outlet, try plugging
it into the same outlet as your amplifier or receiver. If that doesn't work, reverse the polarity of its AC
plug. If you cannot solve the problem, call M&K or your dealer.
5.
If you hear an unusual sound from the subwoofer when no signal or music is playing:
Try removing the input cables as described in Step 4 above. If the noise disappears, it is coming
from another component. If it does not go away, contact your M&K dealer or the factory.
6.
If the subwoofer will not play loud enough, AND it is connected to the SUBWOOFER
OUTPUT jack on a non-THX surround sound processor:
Make sure that the "BASS LEVEL" toggle switch is set to "VARIABLE." Set the "BASS LEVEL"
control to the "MAX" position. If you get bass output, but it is not enough, then the processor's output
level is too low.
A few processors/receivers/amps have very low output levels from their SUBWOOFER OUTPUT
jacks. If you do not have enough gain when using the SUBWOOFER OUTPUT jacks on a non-THX
processor, use the processor's PREAMP OUTPUT jacks. See Figures 5 and 6 (pages 10 and 11).
IF YOU NEED TO REPLACE THE EXTERNAL FUSE:
First, unplug the subwoofer from the wall AC socket. Remove the fuse cap. Look carefully at
the fuse's wire filament inside the glass. If it is broken, replace the fuse ONLY with one identical in size
and value. Using a larger fuse will void your warranty AND MAY CREATE A FIRE HAZARD. Plug the
subwoofer back in. If it does not work, unplug it immediately and contact M&K or your dealer for service.
REPLACEMENT FUSE VALUES
110 VOLT
220 VOLT
220 VOLT
(3 AG 1/4" x 1 1/4" slow blow) (5 X 20 mm IEC-127/III)
V-1250
THX
2 amp
1 amp
T 800 mA (time-lag)
