20
• Are
the
MAIN MIX
Fader
and
SUB
Fad-
ers
turned up?
• If it’s one of the
MAIN OUT
s
, try un-
plugging all the others. For example, if it’s
a TRS
MAIN OUT
, unplug the associated
XLR outputs. If the problem goes away, it’s
not the mixer.
• If it’s a stereo pair, try switching them
around. For example, if a left output is
presumed dead, switch the left and right
cords, at the mixer end. If the left speaker
is still dead, it’s not the mixer.
Noise
• Turn
the
channel Faders
,
EFX 1 RE-
TURN
and
EFX 2 SEND
down, one
by one. If the sound disappears, it’s either
that channel or whatever is plugged into
it, so unplug whatever that is. If the noise
disappears, it’s from your whatever.
Power
• Our favorite question: Is the
POWER
switch on?
APPENDIX A: Service Info
GENERAL PRECAUTIONS AND CONSIDERATIONS
When setting up for a show, oftentimes you
are plugging into an AC power distribution sys-
tem you know nothing about. You may even be
faced with 2-wire outlets that are missing the
third safety ground pin. It’s a good idea to have
a three-wire AC outlet tester in your toolbox
so you can check the outlets yourself to make
sure they are wired correctly. These testers will
tell you if the polarity of the hot and neutral
wires is reversed and if the safety ground is
disconnected. Don’t use an outlet if it is wired
improperly! This is to protect yourself as well
as your equipment.
If you fi nd that you must plug into a two-
wire outlet, you will need to use a two-wire to
three-wire adapter (cheater plug). These come
with a metal tab that you put underneath the
center screw that holds the AC outlet faceplate
in place. This center screw
must
be grounded.
You can check it by connecting the adapter to
the outlet and then plugging in your handy-
dandy AC outlet tester.
NEVER bypass the AC
plug’s ground pin. This is
dangerous!
AC Power Distribution
The majority of AC outlets encountered in
homes and clubs (in the U.S.) are served by a
240VAC center-tapped service entrance trans-
former. This provides two phases of AC power
on either side of the center tap, at 120V each.
If lighting is used in a show, it is preferable
to power the lights from one leg of the service,
and power the audio equipment from the other
leg. This will help minimize noise from the
lights coupling into the audio (particularly if
SCRs, or light-dimmer switches, are used).
In order to minimize ground loops, the safety
grounds for all the outlets should be connected
to a common (“star”) grounding point, and the
distance between the outlets and the common
grounding point should be as short as possible.
If you think your Mackie product has a prob-
lem, please check out the following trouble-
shooting tips and do your best to confi rm the
problem. Visit the Support section of our
website (www.mackie.com/support) where
you will fi nd lots of useful information such as
FAQs and other documentation. You may fi nd
the answer to the problem without having to
send your Mackie product away.
Troubleshooting
Bad Channel
• Is
the
ASSIGN
switch set correctly?
• Is the channel Fader
turned up?
• On mono channels, try unplugging any
INSERT
devices.
• Try the same source signal in another chan-
nel, set up exactly like the suspect channel.
Bad Output
• Are
the
SUB ASSIGN
switches set cor-
rectly?
