Toshiba 29VH14P, Service Manual

Page: 12 / 70

Alignment and Adjustments
4-1
4. Alignment and Adjustments
4-1 General Alignment Instructions
1. Usually, a color TV-VCR needs only slight
touch-up adjustment upon installation. Check
the basic characteristics such as height,
horizontal and vertical sync and focus.
2. Observe the picture for good black and white
details. There should be objectionable color
shading; if color shading is present,
demagnetize, perform purity and convergence
adjustments 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.
4-2 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 is moved or turned in a different direction,
the power should be OFF 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 turning
power OFF.
If color shading persists, perform the
following Color purity and Convergence
adjustments.
4-3 High voltage Check
CAUTION : There is no high voltage adjustment
on this chassis. The B+ power supply should be
+135 volts (with 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. Adjust the Brightness and contrast controls to
both extremes. Ensure that the high voltage
does not exceed 32 KV under any conditions.