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 light up.

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 detected 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 mode (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 troubleshooting 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!

WARNING: The SHORT

LEDs indicate an unsafe

condition for the power

amplifier. When the short-

circuit protection is acti- vated, the SHORT LED

lights, then the PROTECT LED lights. After about four seconds, the protection circuit turns off and the amplifier resumes normal operation. 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.

PROFESSIONAL POWER AMPLIFIER

POWER

19