JVC AV-21L11, AV-21L31, AV-25L31,, Service Manual

Page: 18 / 35

18 No. 51904
AV-21L11
AV-21L31
AV-25L31
ADJUSTMENTS
Item
Measuring
instrument
Test point Adjustment part Description
Check of
B1 POWER
SUPPLY Signal
Generator
DC Voltmeter
B1 (pin 1)
GND (pin 5)
[CN00S
connector] 1. Receive a black and white signal.
2. Connect a DC voltmeter between B1 and GND
(between pins 1 and 5 of the connector CN00S).
3. Make sure that the voltage is DC135 ± 2V .
Adjustment
of FOCUS
FOCUS VR
[In HVT]
Item
Measuring
instrument
Test point Adjustment part Description
FOCUS ADJUSTMENT
B1 POWER SUPPLY
Signal
generator
Notes:
• Set PICTURE MODE (VSM) to “BRIGHT”.
• The final adjustment of CONVERGENCE must be done after the
FOCUS adjustment. (CONVERGENCE is changed by FOCUS ad-
justment.)
When makes difference by FOCUS adjustment, should be reconfirming
PURITY adjustment.
1. Receive a cross-hatch signal.
2. While looking at the screen center, adjust the FOCUS VR so that
the vertical and horizontal lines will be clear and in fine detail.
3. Make sure that the picture is in focus even when the screen gets
darkened.
Adjustment
of VCO (CW)
VCO (CW)
Item
Measuring
instrument
Test point Adjustment part Description
IF CIRCUIT ADJUSTMENT
Remote
control unit
Note:
• Under normal conditions, no adjustment is required.
1. Select 1. IF from the SERVICE MENU.
2. Select 1. VCO by pressing the 1 key on the remote control unit.
3. Receive a broadcast signal.
4. Check the characters color of the
BELOW REFERENCE displayed
to yellow .
5. Press the DISPLAY key three times to return to normal screen.
TOO HIGH
ABOVE REFERENCE
BELOW REFERENCE
TOO LOW
VCO (CW) . MHz
DISPLAY : EXIT
fv
YELLOW
Adjustment
of DELAY
POINT
DELAY POINT
(AGC TAKE-OVER)
Remote
control unit
1. Receive a black and white broadcast signal (color off).
2. Select
1. IF from the SERVICE MENU.
3. Select 2. DELAY POINT by pressing the 2 key on the remote con-
trol unit.
4. Adjust the MENU –/+ key in order to eliminate any noise or beat
from the image. Any increase above the initial value produces noise
and any decrease below it produces beat.
5. Press the DISPLAY key three times to return to the normal screen.
6. Turn to other channels and make sure that there are no irregulari-
ties.
Setting
Initial setting value
(Adjustment time)
DELAY POINT
22
(AGC TAKE-OVER)