Sharp VT-3418X - Page 8

VT-341 8X I
VT-5118X
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ADJUSTMENT OFTHE
TV ELECTRICAL CIRCUITRY
VIDEOKHROMA ADJUSTMENT
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Adjusting Conditions
Adjusting Procedures
1. CRT Cut-off Adjustment
Adjusting Point
Cl R853: Red Bias control
Cl R859: Green Bias control
Cl R865: Blue Bias control
El T602: Screen control (a pat-t of T602)
Cl R857: Green Drive control
!Il R863: Blue Drive control
Note:
Prior to this adjustment, warm up the unit with the
beam current of more than 6OOfl (VT-3418X) I
7004 (VT-51 18X) for more than 30 minutes.
1. Receive “MONOSCOPE PATTERN” signal with
pattern generator.
2. Set Red bias control at MIN (O/l 0) position.
Set Green bias control at MIN (O/l 0) position.
Set Blue bias control at MIN (O/l 0) position.
Set Green drive control at CENTER (5/l 0) position.
Set Blue drive control at CENTER (5/l 0) position.
3. Set the control at the “NORMAL” position that
Contrast is MAX (60), Colour is CENTER (0) an
Brightness is CENTER (0) using control, “A” and
“v” keys.
4. Set the Screen control at MIN (O/l 0) position.
5. Turn on 51401 (Service switch) at the horizontal
line position.
6. Connect the oscilloscope to TP852 (Red Cathode).
2. Sub-Contrast Adjustment
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Adjusting Point
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0 R421: Sub-Contrast control
Note:
Prior to this adjustment, warm up the unit with the
beam current of more than 600@ (VT-3418X) I
7004 (W-51 18X) for more than 30 minutes.
1. Receive “MONOSCOPE PATTERN” signal with
pattern generator.
2. Set the Contrast and Brightness controls at MAX
position.
3. Connect DC milliammeter to TP6019 and
TP602@.
(Full scale: 3 mA)
1. Adjust the Sub-Brightness control (R425) so that
the blanking pulse on oscilloscope is 10 + lVp-p.
2. Slowly turn the Screen control clockwise and stop
it where the horizontal raster appears slightly, in
one of the three colours.
3. Carefully adjust the Bias controls of the other two
colours untii the horizontal raster becomes white.
4. Turn the Screen control counterclockwise until
the horizontal raster disappears, and stop it.
1. Adjust Sub-Contrast control so that the beam
current becomes 0.8 mA (VT-3418X) / 1 .l mA (VT-
5118X).
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