the mixer and the loudspeakers. You may have
your positive and negative connections reversed
at one end of one cable, causing one loud-
speaker to be out-of-phase.
Poor sound
• Is it loud and distorted? Make sure that you’re
not overdriving a stage in the signal chain.
Verify that all level controls are set properly.
• Is the input connector plugged completely into
the jack? Be sure all connections are secure.
Noise
• Make sure all connections to the active loud-
speakers are good and sound.
• Make sure none of the signal cables are routed
near AC cables, power transformers, or other
EMI-inducing devices.
• Is there a light dimmer or other SCR-based
device on the same AC circuit as the HD1521?
Use an AC line filter or plug the HD1521 into a
different AC circuit.
Hum
• Try disconnecting the cable connected to the
main input jack. If the noise disappears, it
could be a “ground loop,” rather than a problem
with the HD1521. Try some of the following
troubleshooting ideas:
• Use balanced connections throughout your
system for the best noise rejection.
• Whenever possible, plug all the audio equip-
ment’s linecords into outlets which share a
common ground. The distance between the
outlets and the common ground should be as
short as possible.
Repair
For warranty service, refer to the warranty informa-
tion on page 15.
Non-warranty service for Mackie products is avail-
able at a factory-authorized service center. To locate
the nearest service center, visit www.mackie.com, click
“Support” and select “Locate a Service Center.” Service
for Mackie products living outside the United States can
be obtained through local dealers or distributors.
If you do not have access to our website, you may call
the Tech Support department at 1-800-898-3211, Mon-
day-Friday, during normal business hours, Pacific Time,
to explain the problem. Tech Support will tell you where
the nearest factory-authorized service center is located
in your area.
Appendix A: Service
Information
If you think your Mackie product 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 send your Mackie
product away.
Troubleshooting
No power
• Is it plugged in? Make sure 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.
• Is the power LED on the rear panel glowing
green? If not, make sure the AC outlet is live. If
so, refer to “No sound” below.
• The internal AC line fuse may be blown. This is
not a user serviceable part. If you suspect the
AC line fuse is blown, please see the "Repair"
section next.
No sound
• Is the input level control for the input source
turned all the way down? Verify that all the
volume controls in the system are properly
adjusted.
• Is the signal source working? Make sure the
connecting cables are in good repair and
securely connected at both ends. Make sure the
output volume (gain) control on the mixing
console is turned up sufficiently to drive the
inputs of the speaker.
• Make sure the mixer does not have a Mute on
or a Processor loop engaged. If you find some-
thing like this, make sure the volume/gain is
turned down before disengaging the offending
switch.
• Is the thermal indicator lit red on the rear
panel? Make sure there is at least six inches of
free space behind the HD1521.
Poor bass performance
• Check the polarity of the connections between
10
HD151
HD15
21
