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Stereo Separation
9. Switch the selector of Stereo Modulator to left channel
modulation.
10. Adjust
R168
so that the output
of right channel
is
minimized.
11. Switch the selector of the modulator to right channel
modulation.
12. Adjust R168 so that the left channel is minimized.
13. Set R168
to a average, if the separation of left and
right is different.
Muting Level
Note:
No adjustment
is necessary. However, if the check-
1.
2.
3:
up is required, take the following steps.
Release the MONO/FM
MUTE OFF pushbutton during
this adjustment procedures.
Connect a VTVM
and an Oscilloscope to the Rec. Out
jacks on the rear panel.
Set the RF generator to 108 MHz, a modulation of 1 kHz
and a deviation of 75 kHz, to provide an input of 8 uV.
. Turn
R138
clockwise
and
remember
the point
(or
position) at which the muting ceases operating.
. Turn R138 counterclockwise slightly so that the output
level drops by 1 cB.
. Attenuate the output of the RF generator to 2 dB from
8 uV of step 2 and check that the muting is still operat-
ing.
6-(2) MVV(LW) Section
Note: ( ) for LW Alignment Procedures
Tracking and Sensitivity
Low Frequency
1. Connect the RF generator to the antenna terminals on
the rear panel, set this to 600 kHz (160 kHz) with 30 %
modulation at 400 Hz.
2. Connect an AC VTVM
and an oscilloscope to the Rec.
out jacks on the rear panel.
3. Set the dial pointer to 600 kHz (160 kHz).
4. Adjust OSC
coil
L351
(L352)
and the ferrite bar an-
tenna core to maximize
the output signal. Left ferrite
bar is for MW
(right ferrite
bar is for LW). Refer to
photo below.
High Frequency
5. Set the RF generator to 1400 kHz (350 kHz) with 30 %
modulation at 400 Hz.
6. Set the dial pointer to 1400 kHz (350 kHz).
7. Adjust the trimmers C361
(C369) and C373 (C374) in
the tuning gang so that the output signal is maximized.
8. Repeat these high and low frequencies adjustment pro-
cedures
alternately
until
maximum
sensitivity
is ob-
tained.
O T.P
(L-E)
O T.P
(L-CH)
©)
Left Channel
Idling C
Adjust
urrent
O T.P
(R-E)
AO,
Right Channel
Idling Current
Adjust
Fig. 10
Adjustment Location on TXX-253 Main Amp. P.C. Board Ass'y
Precaution:
(1) Allow
the set to warm
up at least 5 minutes before
connecting
aDC VT VM.
(2) Must keep the heatsinks cooling to prevent overheating
(
R-S11
and
consequent
destruction
of the
semiconductor
junction
and
set
the volume
control
to minimum
during these adjustment procedures.
): for Right channel Adjustment
L
No. 2517
Procedures:
1. Turn
R719
and
(R720) fully counterclockwise
before
the power switch on.
2. Connect
a DC VTVM
to the Test Point L-CH and L-E
(R-CH and R-E).
3. Adjust R719 (R720) for DC VTVM
reading of 5 mV.
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