McIntosh MC225 User manual

MAINTENANCE
MANUAL
MC225
STEREO
POWERAMPLIFIER
(SerialNos.100C1& above)

Table1.MC225VOLTAGEANDRESISTANCECHART
(SchematicNo.SC126-167A)
Tube
12AX7
(VI)
12AU7
(V2orV3)
12BH7
(V4orV5)
7591
(V6, V7,V8,orV9)
PinNo.
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
DCVolts
115
0
1
FIL
FIL
115
0
1
FIL
295
115
121
FIL
FIL
295
100
121
FIL
285
25
39
FIL
FIL
285
25
39
FIL
FIL
390
390
0.8
-21
FIL
390
Resistancein
Ohms,UnitOff
180K
1M
3.3K
0
0
180K
1M
3.3K
0
27K*
180K
18K
0
0
30K*
2.4M
18K
0
22K*
220K
4.7K
0
0
22K*
220K
4.7K
0
0
62*
130*
40
180K
0
130*
This Resistance measured to positiveside ofB+ rectifierSR2.Warning:
Dischargefiltercondensersbeforemakingmeasurements.
AhighresistanceVTVMisusedforallmeasurements,voltagesandresis-
tancesaretogroundexceptasnoted.

SpecialcomponentsusedintheMC225arelistedbelow.
Thesecomponentsaredesignedandbuiltspecificallyfor
theMC225.TheymaybepurchaseddirectlyfromCustomer
Service,MclntoshLaboratoryInc.Whenyouorderpartsbe
suretogivetheSCHEMATICNO.andDESCRIPTIONfrom
Table2 below,andserialandmodelnumberforyouram-
plifier.
Table2.MC225SPECIALCOMPONENTS
(SchematicNo.SC126-167A)
LABORATORYINC.
2CHAMBERSSTREET,BINGHAMTON,N.Y.
MadeinU.S.A.
Phone-AreaCode607723-5491
2M-AA126-170
COMPONENTNO.
C29A,B,C
L5
R45
SR1, SR2
SR3
Tl
T2
T3
DESCRIPTION
FilterCapacitor,80-35/15MF500/450V
Choke,Filter
Thermistor
SiliconRectifier,500PIV,500MA
SeleniumRectifier,400PIV,75MA
OutputTransformer,TypeM-220A
OutputTransformer,TypeM-220B
PowerTransformer,TypeM-221