FM MPX STEREO
ALIGNMENT
PROCEDURE
INSTRUMENT:
FM Signal Generator, FM Stereo Generator, AC
VTVM,
& Oscilloscope (High Impedance and
Low
Capacity
Probe)
NOTE: Set Function Switch
to
"FM
STEREO"
Set Mode Switch
to
"STEREO"
The FM
Front
End and FM
IF
Amp
Alignment
must
be
completed before attempting this
FM
MPX Stereo
Alignment. Poor
Front
End and IF Alignment
will
result in Poor FM MPX Stereo Adjustment.
FM
Stereo Generator
Output
Indicator Adjustment
Adjust
for
Steps
Signal Modulation
Connected
to
& Function
VTVM
& Oscilloscope
1
Main Signal
100% To
Left
Channel
VR301
0.75V
(RMS)
Output
Tape
Out
Terminal
19KHz Pilot Probe
Of
Oscilloscope
L301, L302
Maximum Reading
2
Signal
Only
Less
5%
To
Test Point
L303
On Oscilloscope
Composite Signal Maximum
Amplitude
3
To
Left
Channel
And Undistortion Sine
Only
1000µV
VTVM
& Oscilloscope
Wave
On Oscilloscope
Signal
To
Left
Channel
L301
Composite Signal
Tape
Out
Terminal
Minimum Reading
4
To
Right
Chan
Pilot
10%
Minimum Reading
Only
5
19KHz
Pilot
5.5%
VR302
Stereo Light
Turn
On
Signal Only
6 Repeat Steps 3 - 4
AUDIO
DRIVER
BIAS ADJUSTMENT
1.
Set volume control
to
minimum
position.
2. Connect 8 ohm load resistor
to
speaker terminals in parallel.
3.
Connect 20
mV
DC
millivolt
meter
to
LEFT
FRONT
(Lf)
channel test
point
TP1
and TP2 (R765).
4. Adjust bias control VR751
until
millivolt
meter indicates 8
mV.
5. Repeat preceding
steps
for
Lb, Rt, and Rb channel.
CHANGING THE STEREO 4CH SWITCH
This receiver operates
at
30W per channel,
four
channels driven, in the
"4CH"
switch position and 70W per channel,
two
channels driven, in the
"Stereo"
switch position.
The switch
is
factory
set in the 4CH position.
To
switch
to
the STEREO mode remove the black screw holding the black lock.
plate
(left
side
of
switch).
Reset
this screw and switch
to
the STEREO position. Replace the lock plate
by
removing the black screw
to
the right
of
the 4CH designation.
Reverse
the plate and reset
so
that
the switch
is
now
locked in the STEREO position. Replace
screw.
When the receiver operates in the STEREO mode the signal
will
only
appear on the
LEFT
FRONT and
RIGHT
FRONT
speaker terminals. There
is
no signal on the
LEFT
&
RIGHT
BACK terminals.
STEREO
4-CH
(QUAD)
Black
Plate
-5-
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