Sig; Protect; Short - Mackie M-2600 Owner's Manual

SIG

SIG (short for "signal present") is the lowest
step in the meter ladder. It senses the signal
prior to the GAIN control, so when SIG is lit,
you know the M•2600 is receiving signal. If it's
the only meter LED lit (meaning the other meter
LEDs are not lit), the M•2600 is receiving a
very weak signal (below –20 dB).

PROTECT

If the PROTECT LEDs are on, the M•2600's
output section has shut down. That, of course,
means you won't hear anything until you rectify
the situation. Three things can cause the
PROTECT circuit to engage:
• Powering up the M•2600. A built-in delay
circuit saves your speakers (and ears)
from the thumps or pops that can some-
times occur when powering up a system.
During this 4-second delay, the PROTECT
LEDs light up.
• A short circuit (or near short) in either of
the outputs. Both the PROTECT and the

SHORT

LEDs light up.
• The temperature in the M•2600 has risen to
an unsafe level. The PROTECT and the
TEMP STATUS HOT LEDs
The M•2600 amp draws its
ventilation air in from the
front and out through the
side panels. The amp
needs plenty of fresh air to
stay cool. DO NOT BLOCK
THE VENTILATION PORTS. See "Thermal
Considerations," on page 29.
SHORT
If this LED comes on, the M•2600 has de-
tected a short circuit in either of the outputs,
meaning that the positive (+) and negative (–)
speaker wires are touching, or a speaker itself
is shorted out. Such a condition causes the
M•2600 to engage its PROTECT
(when a signal is present), muting all signals
at the amp's outputs.
This short-circuit LED is a Mackie exclusive
(until the other guys "borrow" the idea) and
can save precious minutes of your trouble-
shooting time. Without it, you'd still have
speaker and amp protection (via the PROTECT
circuit), but you wouldn't be able to determine
the source of the problem. But with the SHORT
LED, the M•2600 comes right out and tells you!
lights, then the PROTECT LED lights. After
about four seconds, the protection circuit turns
off and the amplifier resumes normal operation.
light up.
If it senses the shorted condition again, the
cycle repeats until you fix the problem.
Typical causes for a "short" indication would
be either a shorted speaker cable or too many
speakers connected to the amplifier (i.e., the
load impedance is too low). If a "short" is indi-
cated, please check your cables. If the cabling
is OK, then reduce the number of speakers
driven by the amplifier.
mode
WARNING: The SHORT
LEDs indicate an unsafe
condition for the power
amplifier. When the short-
circuit protection is acti-
vated, the SHORT LED
19