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Serviceman Mode (Electronic Controls, Cont.)
Audio Adjustment
Serviceman DAC Adjustment (B6)
This adjustment is factory set and needs to be
performed only when IC002 or IC101 is replaced.
Preparation:
1. Apply the following signal at the antenna (70dB
+5dB, 75R open PIS 10dB): audio signal set to
monaural, 300Hz. 100% modulation; video input of
100 IRE flat field, 30% modulation.
2. Connect the RMS Meter with filter jig as shown in
Figure 29.
Procedure:
1. In the Serviceman Mode for making electronic
adjustments, select the Audio Adjustment DAC
(B6) and adjust until 150mV RMS
*
7.5mV RMS is
measured.
2. EXIT the Serviceman Adjustment Mode.
MTS Circuit Adjustments
Note: It is important to adjust the MTS circuit in the
order shown below.
The MTS Circuit Adjustments require four steps:
1. Stereo VCO Adjustment.
2. Filter Adjustment.
3. lnput Level Adjustment.
4. Stereo Separation Adjustment.
Stereo VCO Adjustment (MI)
Preparation:
1. Connect a 1KR resistor between TP14 and
TPA14(GND)
2. Connect a 22pf, 16V Capacitor between TPE1 ("+"
Pin of Cap.) and TPA13 GhlD (Pin
"-"
of Cap.)
3. Connect a frequency counter as follows: Positive
lead (+) to TPEIO' (R-Out), negative lead (-) to
TPA13 (GND).
Note: 15 seconds aging is required prior to
performing the following procedure.
Filter Adjustment (M2)
Preparation:
1. Connect a signal generator (sine wave) to antenna.
& , 4
2. Connect a DVM (AC Range) as follows: Positive
lead (+) to TPE1 and negative lead (-) to GND.
3. Connect a scope as follows: Positive lead (+) to
TPE11, negative lead (-) to TPA13(GND).
Procedure:
1. Apply the following signal from the signal
generator:
Field strength: 70
+
5dB, 75R OPEN, PIS 10dB
Video: 100 IRE flat field, 30% modulation.
Audio: 15.734kHz sine wave.
2. Adjust sine wave signal generator output level
(1 5.734KHz) to obtain 1 OOmV+ 5mVrms at TPEl
.
3. Adjust MTS filter (M2) data
(in the Serviceman
Adjustment Menu)
until the amplitude of the
measured
waveform
on
the
oscilloscope
is minimum.
lnput Level Adjustment (MO)
Preparation:
1. Connect an RMS meter (AC Range) with filter jig
as shown in Figure 30.
2. Connect an RF signal generator to the RF
antenna input.
Procedure:
1. Apply the following signal from the RF signal
generator:
Video: 100 IRE flat field, 30% modulation.
Audio:
300Hz,
100%
modulation,
monaural
(70
*
5dB, 75R OPEN, PIS 10dB)
2. Adjust M O data
in the Serviceman Adjustment Menu)
C
4
until the voltage measured is 190mV
*
10.0mV
rms.
Procedure:
Adjust (MI) MTS-VCO data (in the Serviceman
Adjustment
Menu)
until
the
frequency
counter
measures 15.734kHz
*
50Hz.
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