JBL MPC - Manual (Page 15)

14
AC Power
The MPC amplifiers are available for 120 or 220–240 VAC, 50 or 60 Hz operation. Each
amplifier is factory configured for the line voltage of the market into which it is sold.
Operation
Before first turning on the amplifier, turn the gain controls off—i.e., fully counterclockwise—
until you confirm the amplifier is operating properly.
MPC200 & 200T
Upon turning on the AC switch, the POWER LEDs will light and the amplifier will mute for
3 seconds. After this turn-on sequence, the amplifier should work normally.
Turn up the gain controls until the speakers produce the desired sound levels. The gain
controls should usually be kept in the upper half of their ranges for full performance and
most precise adjustability.
The POWER LEDs indicate the operation of each channel. The red CLIP LEDs indicate
overdrives of their respective amplifier channels.
The mute circuit cuts off the sound as soon as you turn off the amp and mutes for 3 seconds
when you turn on the amplifier. This blocks turn-on and turn-off thumps.
MPC300, 300T, 600, & 600T
When the amplifier is turned on, the red PROTECT LED on each channel lights for about 2
to 3 seconds, during which the output relays mute the speakers. After the turn-on muting
interval, the PROTECT LEDs turn off, the green POWER LEDs light and the output relays
enable the speaker outputs. Even during the muting interval, the yellow SIGNAL and red
CLIP LEDs operate normally if there is a signal present. If the CLIP LED is on while the
amplifier is muted, immediately cut the gain back to avoid a full power blast of sound when
the output relays close. If a channel stays muted with its PROTECT indicator lit, or if its
SIGNAL or CLIP indicators light when the gain is turned all the way down, it may be
defective; see the troubleshooting segment for more information.
The SIGNAL LED indicates signal levels that are -30 dB (referenced to full rated output
power) or higher.
The mute circuit cuts off the sound as soon as you turn off the amp, and the PROTECT
indicators remain lit until the power supplies are discharged.
Protection Circuits
The design of the MPC Series takes a comprehensive approach to protection.
RF Protection—As in all JBL power amplifiers, the inputs are resistively buffered for
overload and RF protection. Chassis bypass capacitors at inputs and outputs further improve
RF rejection.