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AG-520VDH
7.3.7.
SUB CONTRAST ADJUSTMENT
Purpose:
To set the optimum sub contrast level.
Symptom of
The picture is too dark or too light.
Misadjustment:
Test Point :
TP49 (CRT C.B.A.)
Adjustment :
SUB CONTRAST (EVR),
Specification :
Refer to descriptions below.
Input :
Video Input Jack,
Crosshatch Pattern Signal 1 V[p-p] (75 Ω
terminated)
Mode :
STOP
Equipment :
Oscilloscope,
NTSC Video Pattern Generator
1. Supply a Crosshatch Pattern Signal to the Video Input Jack.
2. Connect the Oscilloscope to TP49 on the CRT C.B.A.
(Use TP47 for GND.)
3. Select SUB BRIGHT in EVR adjustment mode. Then, after
making a note of the original value, adjust to the (C0).
4. Select SUB CONTRAST in EVR adjustment mode and
adjust so that the level A is (3.0 V[p-p]±0.1 V[p-p]).
5. Select SUB BRIGHT in EVR adjustment mode and reset to
the original value.
Fig. E3
7.3.8.
FOCUS, SCREEN, CUT OFF, DRIVE
ADJUSTMENT
Purpose:
To set the optimum Screen.
Symptom of
The picture is will be an improper screen
Misadjustment:
color mix.
Test Point :
TP50 (CRT C.B.A.)
Adjustment :
FOCUS CONTROL
(Flyback Transformer),
SCREEN CONTROL (Flyback
Transformer),
SUB BRIGHT (EVR),
G DRIVE (EVR),
B DRIVE (EVR),
R CUT-OFF (EVR),
G CUT-OFF (EVR),
B CUT-OFF (EVR)
Specification :
Refer to descriptions below.
Input :
Video Input Jack,
Crosshatch Pattern Signal,
Monoscope Pattern Signal
Mode :
STOP
Equipment :
Oscilloscope,
NTSC Video Pattern Generator
1. Supply a Crosshatch Pattern Signal to the Video Input Jack.
2. Adjust the FOCUS CONTROL on the Flyback Transformer
so that the "a" and "b" are the sharpest.
3. Supply a Monoscope Pattern Signal to the Video Input
Jack.
4. Connect the Oscilloscope to TP50 on the CRT C.B.A.
(Use TP47 for GND.)
5. Select SUB BRIGHT and move the shaded area to the
value in EVR adjustment mode.
6. Turn the SCREEN CONTROL on the Flyback Transformer
fully counterclockwise.
7. Press DISPLAY key on the remote control for collapse
scan. (Refer to "HOW TO ENTER SERVICE MODE.")
8. Adjust SUB BRIGHT in EVR adjustment mode so that the
level A is (170 VDC±5 VDC).
30
Fig. E4-1
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