Panasonic PT-51HX42CF, Service Manual

Page: 88 / 144

- 48 -
Service Manual
4. Apply the following signal from the RF
signal generator:
Video: 100 IRE flat field, 30% modulation.
Audio: 3KHz, 30% modulation, stereo (left only).
(70dB ± 5dB, 75
Ω
OPEN, P/S 10dB).
Note: Set the 30% modulation with the P.L and
N.R. switches OFF then turn them ON while
testing.
5. Adjust MTS High-Level Separation “SEPAH” DAC
data until the amplitude of the waveform measured
on the scope is minimum.
6. Repeat above steps 2 through 5 until the amplitude
is at minimum for both signals.
Clock Adjustment (CLOCK)
Preparation:
Connect the frequency counter from IC001 MPU
Pin 10 or TPA009, to cold ground ( ).
Note: Frequency Counter probe capacitance should
be 8pF or less.
Procedure:
1.
Turn the PTV “ON” with the AC power applied.
2. Measure TPA009 IC001 MPU pin 10 for frequency
and record the reading.
Note: Pin 10 measurement must have at least four
digits of resolution following the decimal point.
Example: 000.0000
3. Place the PTV into service mode for making
electronic adjustment, select the clock adjustment
DAC CLOCK and change value to 128.
4. Calculate and set CLOCK based on the
following formula:
Note: Pin 10 measurement will not change
regardless of the value stored in CLOCK.
CLOCK
128
0.450x106x
732.422
p
Ð
in
10
( )
Hz
[ ] { }
732.4220
------------------------------------------------------------ + =
-