Samsung CFTD2085X/SMS, Service Manual

Page: 43 / 112

Alignment and Adjustments (Electrical)
4-4 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,
perform the purity and convergence adjust-
ments described below.
3. Use the specified test equipment or its
equivalent.
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
isolation transformer.
4-3-2 Automatic Degaussing
A degaussing coil is mounted around the
picture 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
second after the power is switched ON. If the
set has been moved or turned in a different
direction, 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
adjustment on this chassis. The B+ power
supply must be set to +130 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
current).
3. The high voltage should not exceed 30KV.
4. Adjust the Brightness and contrast controls to
both extremes. Ensure that the high voltage
does not exceed 30KV under any conditions.