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Owner’s Manual
Owner’s Manual
Appendix A: Service Information
• Is the SHORT [4] LED lit? Turn the POWER off,
check the speaker connections and make sure that
there are no strands of wire shorting across the
speaker terminals.
• Is the OVER TEMP [5] LED lit? Make sure there is
cool air available at the rear of the amplifier. Make
sure there is room at the front of the amplifier for
warm air to exit. Allow the amplifier to cool off.
• Is the PROTECT [3] LED lit? The power trans-
former may have overheated and shut down the
amplifier. Turn the amplifier off and wait until
the transformer cools down (it could take several
hours).
• Are there fuses in the speaker or in-line fuses in the
speaker wire? Check ’em to see if they’re blown.
• Make sure the speakers are working properly.
One side is way louder than the other!
• Do the amplifier’s meters [2] read the same on both
sides? If not, your source signal may be delivering
an out-of-balance stereo signal.
• Are both Gain [1] knobs set to the same position?
• Are the speaker(s) impedances matched?
• Try swapping sides: Turn off the amp, swap the
speaker cables at the amp, turn the amp back on.
If the same side is still louder, the problem is with
your speakers or speaker cabling. If the other side
is louder now, the problem is with the mixer, the
amp, or the line-level cabling.
The stereo music sounds kind of sideways,
and the bass frequencies diminish when
standing center, but get louder as you ap-
proach one side!
• Check the polarity of the speaker cable connec-
tions. You may have your positive and negative con-
nections reversed at one end of one speaker cable.
As soon as the music gets loud, the amp
shuts down!
• Check the amplifier’s meters [2]. Be sure that OL is
not lighting up frequently or continuously.
• Can the amp breathe? The M-Series amplifier draws
its ventilation air in from the rear and out through
the front. It needs plenty of fresh air to stay cool.
Do not block the ventilation ports.
• Is the SHORT [4] LED lit? If so, you’ve got a dead
short somewhere in your speaker setup, or the total
impedance of the load is too low. Turn the amp off
and rectify that right away.
Warranty Service
Details concerning Warranty Service are spelled out in
the Warranty section on page 27.
If you think your M-Series amplifier has a problem,
please do everything you can to confirm it before calling
for service. Doing so might save you from the depriva-
tion of your amplifier and the associated suffering.
These may sound obvious to you, but here are some
things you can check. Read on.
Troubleshooting
No Power
• Our favorite question: Is it plugged in? Make sure
the AC outlet is live (check with a tester or lamp).
• Our next favorite question: Is the POWER [6]
switch on? If not, try turning it on.
• Is the light in the power switch illuminated? If not,
make sure the AC outlet is live. If so, refer to “No
Sound” below.
• The AC line breaker on the rear panel has popped.
To reset the breaker, turn the power switch off,
push in the button on the breaker, and turn the
power switch back on.
If the breaker pops again, disconnect the speakers
from the amplifier and repeat the above procedure.
If the breaker pops again, there may be a problem
with the amplifier. Refer to “Repair” on the next
page to find out how to proceed.
No sound!
• Are the Gain [1] controls turned all the way down?
Slowly turn them up and see if you hear anything.
• Is the signal source turned up? Make sure the
signal level from the mixing console (or whatever
device immediately precedes the amplifier) is high
enough to produce sound in the amplifier. The SIG
LEDs [2] should be blinking to indicate that signal
is present.
• If the speakers are wired for BRIDGE mode, make
sure the AMP MODE [8] switch is set to BRIDGE.
• Is the X-OVER [11] switch set to LPF? If so, you are
only getting the lowest frequencies (below 150 Hz)
through the speakers. Set the X-OVER switch to the
FULL position to verify sound is present.