McIntosh MC 300 Service Manual

Page 1

M0300

POWER AMPLIFIER

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MCBDD POWER AMPLIFIER

CONTENTS

Performance Specifications 2 6) Right Front Panel Illumination 13
Rear Panel 3 <5) Left Meter Illumination 14
Front Panel 8 Trim Parts List 3 Right Meter Illumination 14
Notes 3 ® Power Guard Illumination 14
Section Locations 4 ® Meter/Regulator 15-17
Block Diagram 5-6 ® Ampllfler 18-23
Interconnection Diagram 7-10 4? Relay 24-26
Input 11 ~12 Repacking Instructions 27
© Left Front Panel Illumination 13

IIII 11105

Service Manual

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Page 2

STEREO POWER OUTPUT

300 watts into 8, 4, or 2 ohm loads is the
minimum sinewave continuous average power
output per channel from 20Hz to 20,000Hz
with both channels operating. The output RMS
voltage is:

49.0 across 8 ohms

34.6 across 4 ohms

24.5 across 2 ohms

MONO-BRIDGE POWER OUTPUT

600 watts into a 16, 8, or 4 ohm load is the
minimum sinewave continuous average power
output from 20Hz to 20,000Hz. The output
RMS voltage is:

98.0 across 16 ohms

69.3 across 8 ohms

49.0 across 4 ohms

MONO-PARALLEL POWER OUTPUT

600 watts into a 4, 2 or 1 ohm load is the
minimum sinewave continuous average power
output from 20Hz to 20,000Hz. The output
RMS voltage is:

49.0 across 4 ohms

34.6 across 2 ohms

24.5 across 1 ohm

OUTPUT LOAD IMPEDANCE

STEREO

8, 4 or 2 ohms by connecting to the proper
output terminals.

MONO

16, 8, 4, 2 or 1 ohms by connecting to proper
output terminals.

TOTAL HARMONIC DISTORTION

STEREO a

0.005% minimum harmonic distortion at any
power level from 250 milliwatts to rated power
per channel from 20Hz to 20,000Hz, both
channels operating.

MONO

0.005% maximum harmonic distortion at any
power level from 250 milliwatts to rated power
from 20Hz to 20,000Hz.

INTERMODULATION DISTORTION

STEREO

0.005% maximum if instantaneous peak power
output does not exceed twice the output rating
per channel, with both channels operating, for
any combination of frequencies from 20Hz to
20,000Hz.

Performance Specifications

MONO

0.005% maximum if instantaneous peak power
output does not exceed twice the output rating
for any combination of frequencies from 20Hz
to 20,000Hz.

FREQUENCY RESPONSE (at one watt output)
+0, -0.25dB from 20Hz to 20kHz
+0, -3.0dB from 10Hz to 100kHz

HUM AND NOISE (A-weighted)
105dB below rated output

lHF DYNAMIC HEADROOM
1 .9dB

DAMPING FACTOR
Greater than 40

INPUT IMPEDANCE
20,000 ohms Unbalanced
40,000 ohms Balanced

INPUT SENSITIVITY
1.4 with LEVEL Controls at maximum;
2.5V sensitivity marked.

POWER REQUIREMENTS
120VAC, 50/60Hz, 3.3 Amperes UL/CSA
230VAC, 50/60Hz, 1.8 Amperes

MECHANICAL INFORMATION

Size: 17-1/2 inches wide (44.5cm) by 7-1/16
inches high (17.9cm). Depth is 19-3/4 inches
(50.17cm) including connectors. Knob
clearance required in front of the mounting
panel is 1-1/8 inches (2.9cm).

Finish: The front panel is a combination of glass
and black anodized aluminum. The chassis is
black.

Weight: 79 pounds (35.8 kg) net, 97 pounds
(44 kg) in shipping carton.

Page 19

COMPONENTS MARKED WITH
AN ASTERISK I'I ARE ON
REVERSE SIDE OF BOARD

*BS

J4R

d4L

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. n I I

CAPACITOR

PCB 048489
CAPACITOR
PARTS LIST
Symbol Parr Descrip rion
CAPACITORS
C5,C6 066401 ELECT. 30,000uF 100V
DIODES
DI,D2 070031 RECT. 400V, 1.5A
TRANSFORMERS

T1 159215 Current

19

Page 27

In the event it is necessary to repack the
unit for shipment, the unit must be packed exactly as
shown below.

IMPORTANT - The four plastic feet must be
attached to the bottom of the unit so they will locate
in the four holes of the bottom pad. Two #10 x 2-1/4
screws and washers must be used to fasten the unit
securely to the bottom pad and wood skid. Failure to
do this will result in shipping damage.

it a shipping carton or any of the interior
parts is needed, please call or write the Customer
Service Department of McIntosh Laboratory. Order
parts from the accompanying list by part number.

Use the original shipping carton and interior
parts only if they are in good serviceable condition.

TOP PAD \

UNIT WITH
(4) FEET ON
BOTTOM coven

PLASTIC
FOOT (4) \,
10-32 x 43/4" /.
SCREW WlTH

WASHER (4)

BOTTOM PAD
PLASTIC FOOT
SPACEFlS (3)/
wooo SKID "
#10 x 1-3/4"

WASHER (3)

#10 x 2-1/4"
SCREW (3)

INSIDE
CARTON

9 lMPORTANT
- (Flead Above)

Repacking Instructions

Qty. Part No. Description

1 033888 Shipping carton only

4 033887 End cap (Foam pad)

1 033697 Inside carton only

1 033725 Top pad

1 033698 Bottom pad

3 017218 Plastic foot (spacer)

1 033699 Wood skid

3 101169 #10 x 2-1/ " Wood screw
3 104033 #10 x 1-3/ " Flat washer
4 017218 Plastic foot

4 100159 #10-32 x 3/4" Machine screw
4 104083 #10 X 7/16" Flat washer

1 048572 Shipping carton complete

with all the above parts

R END CAP (4)

INSIDE
CARTON

\ SHIPPING

CARTON

27