JVC AV-20220/S, Service Manual

Page: 20 / 54

No. 51787
C-20210
AV-20220
AV-20221
20
Item
Measuring
instrument
Test point Adjustment part Description
MTS SAP
VCO
adjustment
Signal
generator
Frequency
counter
【 【 【 【
MPX
】 】 】 】
Connector
【 【 【 【
4
】 】 】 】
pin SDA
【 【 【 【
3
】 】 】 】
pin GND
R OUT
[AUDIO OUT]
No.8 5FH MON.
No.9 SAP VCO
1. Receive a RF signal (non modulated sound signal) from the
antenna terminal.
2. Connect between pin
【
4
】
of
【
MPX
】
connector and GND (Pin
【
3
】
of
【
MPX
】
connector) through 1M
Ω
Resistor.
3. Select the “No.8 5FH MON.” of the SOUND MODE, and reset
the setting value from 0 to 1.
4. Connect the Frequency Counter to R OUT RCA pin of the
AUDIO OUT.
5. Select the “No.9 SAP VCO”.
6. Set the initial setting value of “No.9 SAP VCO” with the
LEFT/RIGHT key of the menu.
7. Adjust the “No.9 SAP VCO” so that the Frequency Counter will
display 78.67kHz
±
0.5kHz.
8. Select the “No.8 5FH MON.” of the SOUND MODE, and reset
the setting value from 1 to 0.
MTS FILTER
check
No.5 FILTER 1. Select the “No.5 FILTER” of the SOUND MODE.
2. Verify that the “No.5 FILTER” is set at its initial setting value.
MTS
SEPARATION
adjustment
TV audio
multiplex
signal
generator
Oscilloscope
L OUT
R OUT
[AUDIO OUT]
No.6 LOW SEP.
No.7 HI SEP.
1. Input a stereo L signal (300Hz) from the TV audio multiplex
signal generator to the antenna terminal.
2. Connect an oscilloscope to L OUT RCA pin of the AUDIO
OUT, and display one cycle portion of the 300Hz signal.
3. Change the connection of the oscilloscope to R OUT RCA pin
of the AUDIO OUT, and enlarge the voltage axis.
4. Select the “No.6 LOW SEP.” of the SOUND MODE.
5. Set the initial setting value of the “No.6 LOW SEP.” with the
LEFT/RIGHT key of the menu.
6. Adjust the “No.6 LOW SEP.” so that the stroke element of the
300Hz signal will become minimum.
7. Change the signal to 3kHz, and similarly adjust the “No.7 HI
SEP.”.
L-Channel
signal waveform R-Channel
crosstalk portion
Minimum
1 cycle