5
Troubleshooting
If you think your MBM-12 MK2 has a problem, please do everything you can to confirm the problem before contacting us for
service, including reading through the troubleshooting section. Many times the problem actually is caused by other items in the
system or the MBM-12 MK2’s interaction with those items. Much of the time, the service department will not be able to repro-
duce the error.
Problem
Cause
Solution
Humming or
buzzing noise
MBM-12 MK 2
goes into STANDBY
mode while
material is playing.
No output from
the MBM-12 MK2
(the LED does
not light up).
You have an amplifier problem.
Your speaker wires or interconnects are
the cause.
A light dimmer or other triac based (SRC)
device is on the same AC circuit.
You have a problem with other equipment.
The source is not providing enough signal.
AC power is not getting to the amplifier.
The amplifier’s fuse is blown.
• Disconnect all interconnects from the amplifier. If still
hums, call/e-mail technical support.
• It is possible that some cables have a poor or broken
ground due to poor construction, oxidation, or damage.
Also, poorly shielded cables can potentially pick up
noise. Try another interconnect or speaker wire. Also,
move the signal cable away from AC cables, power
transformers, or other EMI sources.
• Use an AC line filter or plug the unit into a different circuit.
• If hum goes away when interconnects are disconnected,
the hum is coming from the rest of your equipment.
Add them back one piece at a time. The one that causes
the system to hum is the source of the hum.
• The unit is going into STANDBY mode during the quiet
passages. Try turning the source signal up. On a Dolby
Digital receiver, turn the SUBWOOFER level up in the
SPEAKER SET-UP menu. After you turn the signal up,
turn down the volume knob on the MBM-12 MK2 to
compensate.
• An alternative is to turn the MBM-12 MK2’s ON/AUTO/OFF
switch to the ON position. It does not use any more
power and does not affect reliability.
• Check that the power cord is plugged in securely at both
ends and make sure that the power outlet the MBM-12
MK2 is plugged into is working.
• Check the fuse. The fuse is located on the amplifier, near
the power plug. Unplug the power cord and remove the
fuse holder with a flat head screwdriver. If the fuse is
blown, the output transistors are probably damaged.
Call/e-mail technical support for authorization to send
the amplifier back for service.
