MAINTENANCE MANUAL
MC275
STEREO POWER AMPLIFIER
(Serial No.'s 275-10001 to 275-10147
and 100E1 & above)
C.T.
AND 600 A
OUTPUT
OUTPUT
600 A
OUTPUT
V
OBTAIN
TO
70.7
600 A
OUTPUT
V
RETURN,
70.7
V
ARE
RECEPTICAL CONNECTIONS
70.7
LEFT
RIGHT
LEFT
OUTPUT
1 AND 7-
1-GROUND,
A/70.7
PIN
600
PINS
RIGHT
5-
3 -
AND
AND
1 AND 8 -
4
2
PINS
PINS
PINS
SERIES CONNECT
OUTPUTS
OR
SINGLE CHANNEL OUTPUT
THE L AND R
DESIRED OUTPUT IMPEDANCE.
PARALLEL
FOR
SINGLE CHANNEL (MONO) OUTPUT NOTE
TO 1%:
TOLERANCE RESISTORS
R24 AND R27
MATCHED
FOLLOWING COMPONENTS
* 5%
A
R49 AND R52
R11 AND R36
R13 AND R38
in
Off
Unit
160K*
1M
Resistance
Ohms
1M
160K*
3.3K
0
160K*
3.3K
18K
37K*
18K
0
40K*
12K*
2.4M"
0
12K
210K
2.7K
0
210K
1M
170K
1M
170K
0
2.7K
0
38**
38**
0
038260
170K
15
6
at
.44
.47
.44
2.1
0
Volts
AC
rated output
Volts
Signal
100
DC
No.
2.1
1000.95
.95
0
0
12
.47
6.3
.96
2.1
0120
100
106
0
240
0
240
.96
6.3
106
84
0
152
12
.7015212.7
365224003652240
112
6.3
0
205
112
152
152
149
-57
-57
149
0
0
6.3
-57
-57
205
0
112
116
149
0 or 6.3
0
450
450
116
6.3 or 0
ground.
-57
ground.
0
.6
to
to
RESISTANCE CHART
AND
1
234&5
Pin No.
678
1
9
234&5
6
1
7
2
8
9
3
4&5
678
1
9
234&56789
1
23456
7
8
VOLTAGE
Tube
12AX7
(VI)
12AU7
(V2 or V5)
12BH7
(V3 or V6)
12AZ7
(V4 or V7)
V10.V11)
V9,
KT88/6550
(V8,
operating voltages.
the
measure
condenser C25A shorted
to
with
used
is
resistance measured
resistance measured with condenser C24B shorted
"This
"This
High impedance VTVM
C
125-109
SC
Special components used in the MC275 are listed below.
These components are designed and built specifically for the
MC275. They may be purchased directly from Mclntosh
Laboratory by ordering from the Service Department. Be
sure to mention "Schematic No.," description, and model
and serial number for your amplifier when ordering parts.
SCHEMATIC NO.
C24,C25,C26,C27
L1, L2, L3, L4
L5
R1, R2, R3
R7
R59
S2
SR1,SR2,SR3,SR4
SR5
T1
T2
T3
DESCRIPTION
Filter Capacitor 100/30 mfd 500/450V
RF Choke
Filter Choke
Gain Control, 250K
Balance Control
Thermistor
Input Selector Switch
Silicon Rectifier, 600 PIV at 500 MA
Selenium Rectifier, 400 PIV at 75 MA
Output Transformer, Type M-216A
Output Transformer, Type M-216B
Power Transformer, Type M-215
2M-HP-761
LABORATORY, INC.
2 CHAMBERS STREET, BINGHAMTON, N. Y.
Made in U.S.A.
Phone-Area Code 607-723-5491
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