JVC AV-20N8(BK) Service Manual page 14

AV-20N8
ADJUSTMENTS
B1 POWER SUPPLY
Measuring
Item
instrument
Check of Signal
B1 POWER Generator
SUPPLY
DC Voltmeter connector]
FOCUS ADJUSTMENT
Measuring
Item
instrument
Adjustment Signal
of FOCUS generator
IF CIRCUIT ADJUSTMENT
Measuring
Item
instrument
Adjustment Remote
of VCO (CW) control unit
VCO (CW)
TOO HIGH
ABOVE REFERENCE
BELOW REFERENCE
TOO LOW
Screen display
TOO HIGH Yellow
ABOVE REFERENCE Blue
BELOW REFERENCE Blue
TOO LOW Blue
14
Test point Adjustment part
TP-91 (B1)
TP-E (" " " " " )
[S1
Test point Adjustment part
FOCUS VR
[In HVT]
Test point Adjustment part
VCO (CW)
TRANSF.
[MAIN PWB]
fv
. MHz
YELLOW
DISP : EXIT
Step
1 2 3
Blue Blue
Yellow Blue
Blue Yellow
Blue
1. Receive a whole black signal.
2. Connect a DC voltmeter between TP-91 (B1) and TP-E (")
(between pins 1 and 5 of the connector S1).
3. Make sure that the voltage is DC114.5
1. Receive a cross-hatch signal.
2. While watching the screen, adjust the FOCUS VR to make the
vertical and horizontal lines as fine and sharp as possible.
3. Make sure that, when the screen is darkened, the lines remain
in good focus.
Under normal conditions, no adjustment is required.
1. Select 1. IF from the SERVICE MENU.
2. Press the 1 key to select 1. VCO.
3. Select a receivable broadcast channel with the CHANNEL key.
4. Turn the core of VCO(CW) TRANSF. until the colour of the
characters "TOO HIGH" displayed on the screen changes from
blue to yellow. (Step 1)
5. Then slowly turn the core of VCO(CW) TRANSF. counterclock-
wise until the characters "ABOVE REFERENCE" changes from
blue to yellow. (Step 2)
6. Further slowly turn the core of VCO(CW) TRANSF. until the
colour of the characters "BELOW REFERENCE" changes from
blue to yellow. (Step 3)
7. Press the DISPLAY key three times to return to normal screen.
8. Perform CHANNEL PRESET again, and make sure that each
broadcast is being received properly.
No. 56030
Description
±
1.5V.
Description
Description