McIntosh MAC 4300V Service Manual

FM
ALIGNMENT
Section
12
-
AM/FM
Tuning
Cantrol
1. In FM
mode, push
the
MANUAL
button and
turn
the manual
tuning
knob fully
CCW.
Adjust
R3 for
3.SVDC
at
J5,
pin
1. If
the
setting
of R3
is changed,
the AM
alignment
must
also
be checked.
Section6-FMTuner
2. Connect
an FM
Stereo
Signal
Generator
to the
FM
ANTENNA
input
jack.
3, Connect
a
Distortion
Analyzer
to
the
VCR,/TAPE
I
outÞuts.
4. Turn
the tuning
knob
to maximum
CCW, then
adjust
the
FM
OSC
coil
(L4)
for
a frequency
display
of
87.5MHz.
5.
Turn
the
tuning
knob
to maximum
CW
and
adjust
the FM
OSC trimmer
capacitor
(C16)
for
a
frequency
display
of
108.SMHZ
6.
Repeat
Steps
4 and
5
as necessary
for
the
tuning range
of 87.5
to 10B.sMHz.
7. Tune
the
generator
and receiver
to
90MHz
and adjust
MIXER
(L5),
RF
(L3),
and ANT
(L1)
coils for
best sensitivity.
B.
Tune
the
generator
and
receiver
to 1O4MHz
and
adjust
MIXER
(C18),
RF
(c1o)
and ANT
(Ct
¡
trimmer
capacitors
for
best
sensitivity,
9.
Repeat
Steps 7
and
B until
no
improvement
in sensitivity
is noted.
10.
Remove
the AM/FM
tuner
cover.
With
the
receiver
tuned
to
90MHz
and no
RF
input,
adjust
the
DETector PRImary (T3)
for-
4,8VDC
at
Jt,
pin
4.
11.
Tune
the
generaton
to
90MHz. Adjust
the
RF
output
to 1000uV
and
10ü6 mono
modulation
at
1000H2.
Adjust
the
DETector
SECondary
(I2)
for
lowest
distortion.
12. Reduce
the
generator
output
to
minimum
and
detune
the
generator
so
the
receiver
picks
up
only noise,
then necheck
the
voltage
at
J1,
pin
4.
If
it is not
4.Br0.2VDC,
repeat
step
10 and
1 1
. If
thene
is interference
fnom
a station
on this frequency,
tune the
receiver
to a nearby
frequency
free from
interference
for
this
measurement.
13. Turn
the
STEREO
BLEND
pot (R32)
fulty
CW.
Connect
a Frequency
Counter
to
Ïpl
and
adjust
I9kHz
(R21)
for
a
frequency
of
.t9
t
.05kHz.
14.
Tune
the
generator
to
90MHz with
a 1000uV
output.
Switch the
generator
to stereo
(Ieft
only)
and
adjust the
IF INPUT
transformer
(T1
)
for
the lowest
distortion
at
the Left
VCR/TAPE'l
output.
15. Adjust
the
SIGNAL
STRENGTH
pot (R54)
Cw
to the
point
where
all
10 LED
dots are lit.
16. Switch
the
analyzer
to
the
right
VCR,/TApE
1
output
and
adjust
the Right
MpX
SEParation
pot (
R1
3)
for
best sepanation
(minimum
output).
'17.
Switch
the
generator
to
the
right
channel
and
the
analyzer
to the left
channel.
Adjust
the
Left
MPX
SEparation
por (R15)
for
best separation,
(minimum
output)
18,
Reduce
the
generator
output to
50uV
and
adjust the
STEREo
BLEND
pot (R32)
for
20dB
separation.
19. Reduce
the
generator
output
to 2.Suy
and
adjust
the MUTING/STEREO
SWITCH
pot
(R4B)
so the
MPX light
just
comes
on.
Al¡gnment
Procedure
Section 1O
-
Frequency
CoLnter
20. Remove
the
generator
and
connect
an
antenna.
Tune
to a
station
of known
frequency
and
check for
proper
frequency
display.
If necessary,
adjust
the FM
DISPLAY FREO pot (
R1
2)
for
the
correct
frequency
reading.
AM ALIGNMENT
Section
12
-
AM/FM
Tuning
Control
1. In
AM mode, push
the
MANUAL
button
and
turn
the
manual
tuning knob fully
CCW.
Adjust
R3 for
3.sVDC at
J5,
pin
1. If
the
setting
of
R3
is
changed,
the
FM
alignment
must
also
be checked.
Section
5
-
AM
Tuner
(remove
cover)
2. Connect
an AM
Signal
Generator
to
the IF
INJECTION
(fP2\,
Connect a
Distortion
Analyzer
to the VCR/TAPE
i
OUTPUT.
3.
Set the
generator
frequency
to 45510.5kH2
and modulate
3ú at AOOHZ.
Increase
the RF
output
to
1O,000uV
and adjust
the
AM
DET
OFFSET
(T2)
for
4,BVDC
at
J1,
pin
4.
4. Reduce
the RF
output to 1
000uV
or less.
Adjust
the AM
MIXER
transformer
(T5)
for
maximum
audio
at the VCR,/TAPE
I
OUTPUT.
Disconnect TP2.
5.
Turn
the manual
tuning knob
to maximum
CCW
and adjust
the
AM
OSC coil
(T1
)
for
a
frequency
display
of
535kHz.
6.
Turn
the
tuning
knob to
maximum
CW and
adjust
the
AM
OSC trimmer
capacitor
(C1B)
for
a frequency
display
ol 162OkHz.
7.
Repeat
Steps
5
and
6 as
necessary
for
the
tuning
range
of 535kHz to 1620kH2.
B. Connect the
generator
to
the
AM
ANTENNA
and
GND
Terminals.
9.
Tune
the
generator
and
receiver
to
6OOkHz,
then
adjust
the RF
(T3)
and MIXER
(T4)
coils
for
best
sensitivity.
10. Tune
the
generator
and
receiver
to 14OOkHz,
then
adjust RF
(C19),
and MIXER
(CZZ)
trimmer
capacitors
for
best sensitivity.
11.
Repeat
Steps
g
and 10
until
no
improvement
in sensitivity
is noted.
Sectisr 10
-
Frequency
Counter
12,
Disconnect
the
generator
and connect
an
antenna.
Tune
with
a SCAN
button
to a
station
of known
frequency
and check for^
proper
frequency
display.
If
necessary,
adjust
the AM
DISPLAY
FREO
pot (Rt0)
for
the
correct
frequency
reading.
POWER
AMPLIFIER
BIAS
Section 4
-
Power Amplifier
1. Operate
the
MAC430OV for
5
minutes
or
longer
with no
audio
output.
2.
Connect
Digital Voltmeter
test leads
to Tpl
and 1P2
on the Heat
Sink
PC
board. Take
precautions
to
prevent
accidental
shorts
which may
damage
the amplifier.
3.
Adjust
the
BIAS
pot (R31)
for 7-1OmV.
4. Perform
steps
2
and 3
for
the
other
channel.
49

McIntosh MAC 4300V Specifications

General

Brand	McIntosh
Model	MAC 4300V
Category	Receiver
Language	English