Panasonic AP364, Service Manual

Page: 24 / 48

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Vertical Size
Service DAC Adjustment (C6)
Preparation:
Connect a monoscope pattern.
Procedure:
1.
In the Service Mode, select the Vertical Size
Adjustment DAC (C6). Adjust until a perfect circle
appears (Upper and lower sections of circle may
extend beyond the screen and therefore not
visible). See Fig. 24.
2. EXIT the Service Adjustment Mode.
MTS Circuit Adjustments
The MTS Circuit Adjustments require two steps:
1. Input Level Adjustment.
2. Stereo Separation Adjustment.
Input Level Adjustment (M0)
Preparation:
1. Connect an RMS meter with filter jig as shown in
Fig. 25.
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, 75
Ω
OPEN, P/S 10dB).
2. Adjust the MTS Input Level Adjustment (M0) until
the voltage measured is 106 ± 6.0mV rms.
Stereo Separation Adjustment (M1 & M2)
Preparation:
1. Connect an RF signal generator to the RF antenna
input.
2. Connect a scope to TPE10.
Procedure:
1.
Select Stereo Mode in Audio menu
2. Apply the following signal from the RF signal
generator:
Video: 100 IRE flat field, 30% modulation.
Audio: 300Hz, 100% modulation, stereo (left only)
(70 ±5dB, 75
Ω
OPEN, P/S 10dB).
3. Adjust the MTS Low-Level Separation Adjustment
(M2) until the amplitude displayed on the scope
is minimum.
4. Apply the following signal from the RF
signal generator:
Video: 100 IRE flat field, 30% modulation.
Audio: 3KHz, 100% modulation, stereo (left only)
(70 ±5dB, 75
Ω
OPEN, P/S 10dB).
5. Adjust the MTS High-Level Separation Adjustment
(M1) until the amplitude displayed on the scope is
minimum. Repeat above steps 2 through 5 until the
amplitude is at minimum for both signals.
Clock Adjustment (X3)
Preparation:
Connect the frequency counter from TP5 (IC001
Pin 11) to cold ground ( ).
Note: Frequency Counter probe capacitance should
be 8pF or less.
Procedure:
1.
Turn the Receiver “OFF” with the AC
power applied.
2. Measure TP5 (IC001 pin 11) for the frequency of
the waveform and record the reading.
Note: Pin 11 measurement must have at least four
digits of resolution following the decimal point.
Example: 000.0000
3. Turn the Receiver back “ON”.
4. Place the Receiver into Service Mode for making
electronic adjustment, select the Clock Adjustment
DAC (X3).
5. Calculate and set X3 based on the following
formula:
Note: Pin 11 measurement will not change
regardless of the value stored in X3.
Figure 23. Horizontal Centering
Figure 24. Vertical Size
TPE11
Figure 25. Filter Jig
8.5
X3
128 0.9
6
×
10
TP5 125
–
( ) { }
125
----------------------------------- + =