Appendix A: Service Information - Mackie MX Series Owner's Manual

Appendix A: Service Information

If you think your MX Series amplifier has a problem,
please check out the following troubleshooting tips
and do your best to confirm the problem. Visit the Support
section of our website (www.mackie.com/support) where
you will find lots of useful information such as FAQs
and other documentation. You may find the answer
to the problem without having to part with your amplifier.
Troubleshooting
No power
• Our favorite question: Is it plugged in? Make sure
the power cord is securely seated in the IEC socket
and plugged all the way into the AC outlet and that
the AC outlet is live [check with a tester or lamp].
• Our next favorite question: Is the power switch on?
If not, try turning it on.
• Make sure the line cord is securely seated in the line
cord socket and plugged all the way into the AC outlet.
• Are the power LEDs on the front panel illuminated?
If not, make sure the AC outlet is live. If so, refer
to "No sound" below.
• If nothing is illuminated, and you are certain that
the AC outlet is live, it will be necessary to have your
amplifier serviced. There are no user serviceable parts
inside. Refer to "Repair" on the next page to find out
how to proceed.
No sound or low output
• Loudspeaker cables or connectors are not wired
correctly or they are faulty. Check all cabling, referring
to these instructions for the correct connections.
The best way to check a suspect cable is to swap
it with a known good cable. Read the loudspeaker's
input panel to verify correct cable connections.
• Loudspeaker is not working. Connect the loudspeaker
cable to a known good loudspeaker leaving all
equipment set to the same levels. If the problem
disappears, the loudspeaker is probably not working
correctly.
• Is the level knob for the input source turned all the way
down? Verify that all the volume controls in the system
are properly adjusted. Look at the level meter
to ensure that the mixer is receiving a signal.
• 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
14
MX Series Professional Power Amplifiers
LEDs should be blinking to indicate that signal
is present.
• If the speakers are wired for bridge mode, make sure
the amp mode switch is set to bridge.
• If the amplifier has become extremely hot, the thermal
protection circuit may have activated. Allow the
amplifier to cool down and normal operation should
resume.
• Make sure the mixer does not have a mute on
or a processor loop engaged. If you find something
like this, make sure the level is turned down before
disengaging the offending switch.
• Has it shut down? Make sure there is at least six
inches of free space behind each MX amplifier.
Poor or distorted sound
• The power amplifier is clipping. The signal level
is exceeding the limits of the system and you must
reduce the level from the mixer or signal source.
• The loudspeaker(s) are being overdriven. Turn down
the volume to see if the distortion goes away. If not,
review the owner's manual for the loudspeakers
to ensure that they are a proper match for the
amplifiers.
• Ensure that no equipment in the signal chain is being
overdriven. For example: input(s) or summing bus
in the mixing console, equalizers, etc.
• Is the input connector plugged completely into
the jack? Be sure all connections are secure.
• If possible, listen to the signal source with headphones
plugged into the console. If it sounds bad there,
the problem is not in the amplifier.
Poor bass performance
• Check the polarity of the speaker cable connections.
You may have your positive and negative reversed
at one end of one speaker cable.
• Poor bass performance may be the result
of bad AC power. See the section titled 'AC Power
Requirements' on the previous page for further details.