Samsung CK765DWT2X, Service Manual

Page: 20 / 55

Alignment and Adjustments
4-6 Samsung Electronics
4-3 Other Adjustments
4-3-1 General
1. Usually, a color TV needs only slight touch-
up adjustment upon installation. Check the
basic characteristics such as height, horizontal
and vertical sync and focus.
2. The picture should have good black and white
details. There should be no objectionable
color shading; if color shading is present, per-
form the purity and convergence adjustments
described below.
3. Use the specified test equipment or its equiva-
lent.
4. Correct impedance matching is essential.
5. Avoid overload. Excessive signal from a sweep
generator might overload the front-end of the
TV. When inserting signal markers, do not
allow the marker generator to distort test
results.
6. Connect the TV only to an AC power source
with voltage and frequency as specified on the
backcover nameplate.
7. Do not attempt to connect or disconnect any
wires while the TV is turned on. Make sure
that the power cord is disconnected before
replacing any parts.
8. To protect against shock hazard, use an isola-
tion transformer.
4-3-2 Automatic Degaussing
A degaussing coil is mounted around the pic-
ture tube, so that external degaussing after
moving the TV should be unnecessary. But
the receiver must be properly degaussed upon
installation.
The degaussing coil operates for about 1 sec-
ond after the power is switched ON. If the set
has been moved or turned in a different direc-
tion, disconnect its AC power for at least 10
minutes.
If the chassis or parts of the cabinet become
magnetized, poor color purity will result. If
this happens, use an external degaussing coil.
Slowly move the degaussing coil around the
faceplate of the picture tube and the sides and
front of the receiver. Slowly withdraw the coil
to a distance of about 6 feet before removing
power.
4-3-3 High Voltage Check
CAUTION: There is no high voltage adjust-
ment on this chassis. The B+ power supply
must be set to +130/155 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 pic-
ture.
3. Adjust the FOCUS control for well defined
scanning lines in the center area of the screen.
4-3-5 Screen Adjustment
1. Turn to the ACTIVE channel.
2. Adjust the VR screen for a normal picture is
(no blooming or flyback line).
3. Adjust the FOCUS control for well defined
scanning lines in the center area of the screen.