McIntosh MC275 User manual

MAINTENANCEMANUAL
MC275
STEREOPOWERAMPLIFIER
(SerialNo.'s275-10001to275-10147
and100E1& above)

600
A/70.7
OUTPUT
RECEPTICALCONNECTIONS
PIN
1-GROUND,
70.7
V
RETURN,
AND600A
C.T.
PINS
1 AND7-
LEFT
70.7
V
OUTPUT
PINS
2
AND
3 -
LEFT
600A
OUTPUT
PINS
1 AND8 -
RIGHT
70.7
V
OUTPUT
PINS
4
AND
5-
RIGHT
600A
OUTPUT
SINGLECHANNEL(MONO)OUTPUTNOTE
FOR
SINGLECHANNELOUTPUT
PARALLEL
OR
SERIESCONNECT
THEL ANDR
OUTPUTS
TO
OBTAIN
DESIREDOUTPUTIMPEDANCE.
*5%
TOLERANCERESISTORS
A
FOLLOWINGCOMPONENTS
ARE
MATCHED
TO1%:
R11ANDR36 R13ANDR38
R24ANDR27 R49ANDR52
VOLTAGE
AND
RESISTANCECHART
"This
resistancemeasured
with
condenserC25Ashorted
to
ground.
"This
resistancemeasuredwithcondenserC24Bshorted
to
ground.
HighimpedanceVTVM
is
used
to
measure
the
operatingvoltages.
Resistance
in
Ohms
Unit
Off
AC
Volts
at
ratedoutput
DC
Volts
No.
Signal
PinNo.
Tube
160K* 1M
3.3K 0
160K*
1M
3.3K
2.1
.47 .44
0 2.1
.47
.44
6.3
100
0
.95 0
100
0
.95
0
1
2 3 4&5 6
7
8 9
12AX7
(VI)
37K*
160K* 18K
0 40K* 2.4M"
18K
0
12
2.1
.96
0
12
0
.96
6.3
240
100 106
0 240 84
106
0
1
2
3
4&5
6 7
8 9
12AU7 (V2orV5)
12K*
210K 2.7K 0
12K
210K 2.7K 0
152 12
.7
0
152
12
.7
6.3
365 22 40 0 365 22 40 0
1
2
3 4&5 6
7
8 9
12BH7
(V3orV6)
38**
1M 170K
0 38**
1M 170K
0
112
152 149
0
112 152 149
6.3
205
-57 -57
0 205
-57 -57
0
1
2 3 4&5
6
7 8 9
12AZ7
(V4orV7)
0 38 260
170K
6
15
0or6.3
116
112
149
6.3or0
116
0
450 450
-57
0 .6
1
2 3 4 5 6 7
8
KT88/6550 (V8,
V9,
V10.V11)

SC
125-109
C

SpecialcomponentsusedintheMC275arelistedbelow.
Thesecomponentsaredesignedandbuiltspecificallyforthe
MC275.TheymaybepurchaseddirectlyfromMclntosh
LaboratorybyorderingfromtheServiceDepartment.Be
suretomention"SchematicNo.,"description,andmodel
andserialnumberforyouramplifierwhenorderingparts.
LABORATORY,INC.
2CHAMBERSSTREET,BINGHAMTON,N.Y.
MadeinU.S.A.
Phone-AreaCode607-723-5491
2M-HP-761
SCHEMATICNO.
C24,C25,C26,C27
L1,L2,L3,L4
L5
R1,R2,R3
R7
R59
S2
SR1,SR2,SR3,SR4
SR5
T1
T2
T3
DESCRIPTION
FilterCapacitor100/30mfd500/450V
RFChoke
FilterChoke
GainControl,250K
BalanceControl
Thermistor
InputSelectorSwitch
SiliconRectifier,600PIVat500MA
SeleniumRectifier,400PIVat75MA
OutputTransformer,TypeM-216A
OutputTransformer,TypeM-216B
PowerTransformer,TypeM-215