Samsung CK765DSX3X/NWT, Service Manual

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Alignment and Adjustments
4-6 Samsung Electronics
Alignment and Adjustments
4-3-3 High Voltage Check
CAUTION: There is no high voltage adjustment on this chassis.
The B+ power supply must be set to +155 volts (Full color bar input
and normal picture level).
1. Connect a digital voltmeter to the second
anode of the picture tube.
2. Turn on the TV. Set the Brightness and
Contrast controls to minimum (zero beam cur-
rent).
3. The high voltage should not exceed 33KV.
4. Adjust the Brightness and contrast controls to
both extremes. Ensure that the high voltage
does not exceed 33KV under any conditions.
4-3-4 FOCUS Adjustment
1. Input a black and white signal.
2. Adjust the tuning control for the clearest
picture.
3. Adjust the FOCUS control for well defined
scanning lines in the center area of the screen.
4-3-5 Screen Adjustment
1. Connect CRT socket pin GK, BK, RK to an
oscilloscope probe.
2. Input a gray scale pattern. (Use a pattern
generator, PM5518)
3. Use the Picture mode for the STANDARD pic-
ture.
4. Adjust the Screen VR (on the FBT) so that the
voltage on the oscilloscope becomes 140+2.5V
(See Fig. 4-1).
4-3-6 Purity Adjustment
1. Warm up the receiver for at least 20 minutes.
2. Plug in the CRT deflection yoke and tighten
the clamp screw.
3. Plug the convergence yoke into the CRT and
set in as shown in Fig. 4-2.
4. Input a black and white signal.
5. Fully demagnetize the receiver by applying an
external degaussing coil.
6. Turn the CONTRAST and BRIGHTNESS con-
trols to maximum.
7. Loosen the clamp screw holding the yoke.
Slide the yoke backward or forward to pro-
vide vertical green belt. (Fig. 4-3).
8. Tighten the convergence yoke.
9. Slowly move the deflection yoke forward,
and adjust for the best overall green screen.
10. Temporarily tighten the deflection yoke.
11. Produce blue and red rasters by adjusting the
low-light controls. Check for good purity in
each field.
12. Tighten the deflection yoke.
Fig. 4-1
140 2.5V
+_
GND
_