JVC AV-21F8, Руководство по обслуживанию

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AV-20N8
No. 56030 14
Description
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
±
1.5V.
Description
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.
Measuring
Item Test point Adjustment part
instrument
Adjustment Remote VCO (CW)
of VCO (CW) control unit TRANSF.
[MAIN PWB]
Description
●
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.
ADJUSTMENTS
B1 POWER SUPPLY
Measuring
Item Test point Adjustment part
instrument
Check of Signal TP-91 (B1)
B1 POWER Generator TP-E (
" " " " "
)
SUPPLY [S1
DC Voltmeter connector]
Measuring
Item Test point Adjustment part
instrument
Adjustment Signal FOCUS VR
of FOCUS generator [In HVT]
FOCUS ADJUSTMENT
IF CIRCUIT ADJUSTMENT
Step
Screen display
1 2 3
TOO HIGH Yellow Blue Blue
ABOVE REFERENCE Blue Yellow Blue
BELOW REFERENCE Blue Blue Yellow
TOO LOW Blue Blue
TOO HIGH
ABOVE REFERENCE
BELOW REFERENCE
TOO LOW
VCO (CW)
✽✽✽
.
✽✽
MHz
DISP : EXIT
fv
YELLOW