page 14powered subwoofers
.
MX-70B:
The MX-70B gives a very high level of performance in a compact cabinet. Therefore, it is likely
to be installed in both vertical and horizontal locations. To avoid having its inverted driver exposed in
installations where the cabinet is horizontal, the MX-70B has two speaker grills.
If your MX-70B has a solid grille over the inverted driver, leave this grille in place. The
MX-70B is designed so that the sound eminating from this driver comes from the opening in the front
baffle. The solid grille cover insures that this is the case.
12. TROUBLESHOOTING
Your M&K Subwoofer amplifier circuit provides high reliability, and, if necessary, easy modular
replacement of parts. This guide will help you to solve or diagnose most problems that can occur with
your Subwoofer. In the event that a fuse blows, you must replace it with a fuse of the correct value
to avoid a fire hazard and to maintain your warranty protection.
1. If your Subwoofer has no output:
a. Make sure that the Subwoofer is plugged into an AC outlet.
b. Check the "BASS LEVEL" control and make sure that it is set above the
"MIN" position. Rotate it clockwise if it is set to the "MIN" position.
c. Check the red LED on the Subwoofer's back panel. If the LED is not lit,
check the AC fuse next to the LED. Unplug the Subwoofer before
changing the fuse. See instructions on Page 16. If the element inside the
fuse is broken, replace the fuse. If it blows again, contact your dealer or M&K.
d. If the red LED is lit, try this test: Turn the "BASS LEVEL" control to
"MIN". Plug a standard RCA cable into the "FROM PREAMP" jacks.
Lightly touch the plug at the free end of the cable, while slowly turning the
"BASS LEVEL" control clockwise. If you hear noise from the Subwoofer when
you touch the cable, the Subwoofer is functioning. Look elsewhere in your
system for the problem. If you hear no noise, contact your dealer or M&K.
e. Make sure that the input cables are OK. Double check your connections. If
necessary, replace any defective cables or speaker wires.
2. If, after operating the woofer at high volume levels for a long time, the woofer
cuts out or becomes intermittent:
Your Subwoofer has a protection circuit that protects it from overheating. After
hours of continuous operation at extremely high volume levels, this circuit may
kill the power to the Subwoofer. When it activates, the sound may switch in and
out rapidly, with a fluttering sound. If this happens, unplug the unit and let it sit for
at least half an hour. After that time, plug it back in. It should operate normally.
If you find this happens frequently, contact the factory for advice.
3. If you are using the "FROM AMPLIFIER" terminals, and the Subwoofer has very
little output: