Mts Circuit Adjustment - Panasonic TC-23LX60 Service Manual

11 MTS circuit adjustment

The MTS circuit adjustment require two steps:
1. Input level adjustment.
2. Stereo separation adjustment.
Input level adjustment
Service DAC adjustment (MTSIN)
PREPARATION
1. Connect an RMS meter with filter jig as shown in figure
to TP1105 or TP1107 and gound.
2. Connect an RF sigal generator to the RF antenna Input.
PROCEDURE
1. Apply the following signal from the RF signal generator.
• Video: flat field, 30% modulation (70±5dB, 75 ohm
OPEN, P/S 10dB).
• Audio:
300Hz,
(70±5dB, 75 ohm OPEN, P/S 10dB.) Make sure that
the 75µs pre-emphasis is OFF.
2. Adjust the MTS input level adjustment "MTSIN" data
until the RMS voltage measured is 106mVrms ±
6.0mVrms.
Stereo separation adjustment (SEPAH)
PREPARATION
1. Connect an R.F. signal generator to the RF antenna
input.
2. Connect a scope to TP1104 or TP1106 and ground.
PROCEDURE
1. Select stereo mode in audio menu.
2. Apply the following signal from the RF signal generator.
• Video: flat field, 30% modulation.
• Audio: 300Hz, 30% modulation, stereo (left only)
(70±5dB, 75 ohm OPEN, P/S 10dB.)
Note: After setting 30% modulation with P.L. SW
and N.R. SW OFF, turn P.L. SW and N.R. SW ON.
3. In service mode, adjust the MTS Low-Level separation
adjustment "SEPAL" data until the amplitude displayed
on the scope is minimum.
4. Apply the following signal from the RF signal generator.
• Video: flat field, 30% modulation.
• Audio: 300Hz, 30% modulation, stereo (left only)
(70±5dB, 75 ohm OPEN, P/S 10dB.)
Note: After setting 30% modulation with P.L. SW
and N.R. SW OFF, turn P.L. SW and N.R. SW ON.
5. Adjust the MTS High-level separation adjustment
"SEPAH" until the amplitude displayed on the scope is
minimum.
6. Repeat above steps 2 through 5 until the amplitude is at
minimum for both signals.
100% modulation, monaural
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