13
Input Switch
The Input Mode Switch, which is
located on the Rear Panel of the
MC1502, allows selection of either
the Balanced or Unbalanced Input.
Refer to figure 12.
Auto Off Switch
The MC1502 incorporates Power Save Circuitry to
automatically place the MC1502 into the power saving
Standby Mode approximately 30 minutes after there
has been an absence of an audio input signal.
When there is a Power Control
Connection between the MC1502
and a Preamplifier with Power
Save Circuitry, the AUTO OFF
Switch is bypassed (located on the
Rear Panel of the MC1502). Refer to figure 13.
In the event there is no Power Control Connection
and the Power Save Circuitry is activating inappro-
priately relative to your specific use of the MC1502,
place the AUTO OFF Switch in the DISABLE posi-
tion.
Note: If the Power Save Circuitry has switched Power
to the MC1502 OFF, place the POWER in the
OFF Position and then in the ON position to
reset the circuitry.
Sentry Monitor
The MC1502 Sentry Monitor Tube Protection
Circuitry provides protection to the Power Amplifier
in the event of an impedance mismatch between
the MC1502 and the Loudspeaker(s). It will also
activate if there is a short circuit at the MC1502
Output Terminals (or the Loudspeaker Terminals) or
if a MC1502 Power Output Tube should fail. During
How to Operate
How to Operate
Power Control
The POWER CONTROL is located on the Front Panel
of the MC1502. Set the Control
to the REMOTE Position. Refer
to figure 10. The MC1502 Power
Amplifier will turn ON or OFF as
the Preamplifier it is connected to
(via the Power Control Connection)
turns On or Off . For manual operation, place the
POWER CONTROL to the ON Position as desired.
The LED indicator located on the Front Panel is
illuminated when the MC1502 is connected to an
active AC Outlet.
Note: When the MC1502 is first switched On, there
is a Warm-Up period of time during which no
sound will be heard. There is also sequential
illumination (amber color) of the Small Signal
Vacuum Tubes. After the Warm-Up period of
time, sound will be heard and the illumination
color of the Small Signal Vacuum Tubes will
change to Green. The Illumination of Small
Signal Vacuum Tubes can also be switched OFF,
by placing the TUBE LIGHT Control in the OFF
position.
Tube Lights Control
The eight Small Signal Vacuum Tubes are Illuminated
by LEDs to indicate the various Operation Modes
of the MC1502 Power Amplifier. Refer to the Left
and Right Channel Charts located on page 12. When
the MC1502 Power Amplifier is in the Normal
Mode of Operation, the default
LED Illuminating Color is Green.
Rotating the TUBE LIGHTS
CONTROL counterclockwise turn
the tube lights off. Refer to figure
11.
Notes: 1. The impedance of a Loudspeaker actually varies as
the Loudspeaker reproduces different frequencies.
As a result, the nominal impedance rating of the
Loudspeaker (usually measured at a midrange
frequency) might not always agree with the
impedance of the Loudspeaker at low frequencies
where the greatest amount of power is required.
Contact the Loudspeaker Manufacturer for
additional information about the actual impedance
of the Loudspeaker before connecting it to the
McIntosh MC1502.
2. When the given channel doesn’t return to Normal
Operating after the Power Switch has been switched
back ON, then place the Power Switch in the OFF
position and disconnect the AC Power Cord from
the MC152. Then contact your McIntosh Dealer for
repair of the Power Ampifier.
Figure 10
REMOTE
OFF
ON
POWER
Figure 11
ON
TUBE LIGHTS
OFF
Figure 12
INPUT
INPUT MODE
MODE
BALANCED
BALANCED
UNBALANCED
UNBALANCED
AUT
AUTO OFF
O OFF
ENABLED
ENABLED
DISABLED
DISABLED
Figure 13
normal operation the Sentry Monitor Tube Protection
Circuitry has no effect on the performance of the
Power Amplifier.
In the event a problem occurs, the circuitry will
activate to prevent potentially destructive high levels
of current from flowing in the amplifier. The illumi-
nation color of the Small Signal Vacuum Tubes of the
affected channel will change from Green to Red. To
reset the Sentry Monitor Tube Protection Circuitry
first note the position of the POWER Switch. If the
POWER Switch is set to the REMOTE position,
switch Off the Preamplifier for approximately one
minute and then switch the Preamplifier On. When
the POWER Switch is set to the ON position, place the
POWER Switch to the OFF position for approximately
one minute, then place the POWER Switch to the ON
position.
