General Adjustments; Vertical Height Adjustment; Focus Adjustment - Daewoo CN-150 Service Manual

GENERAL ADJUSTMENTS

1. GENERAL
In the majority of cases, all color televisions will need only
slight touch-up adjustment upon installation. Check the
basic characteristics such as height, focus and sub-
bright. Observe the picture for good black and white
details without objectionable color shading. If color
shading is evident, demagentize the receiver. If color
shading still persists, perform purity and convergence
adjustments. This should be all that is necessary to
achieve Optimum receiver performance.

2. VERTICAL HEIGHT ADJUSTMENT

1) Tune in an active channel.
2) Adjust brightness and contrast controls for a good
picture.
3) Adjust vertical height control (R315) for approximately
one half inch over scan at top and bottom of picture
screen.
4) Vertical centering adjustment VR316
Horizontal centering adjustment VR556.

3. FOCUS ADJUSTMENT

1) Tune in an active channel.
2) Adjust brightness, sharpness and contrast controls for a
good picture.
3) Adjust focus control (part of T402) for sharp scanning
lines and/or sharp picture.
4. RF AGC ADJUSTMENT
1) Tune in an active channel.
2) Using the attenuator, apply the signal of 60dBm to the
antenna input terminal.
3) Turn RF AGC control (VR555) full clockwise until snow
or/and noise appears in the picture, then slowly turn
control counterclockwise until snow or/and noise
disappears.
5. HIGH VOLTAGE CHECK
High voltage is not adjustable but must be checked to
verify that the receiver is operating within safe and
efficient design limitations as specified:
1) Operate Receiver for at least 15 minutes at 120V AC
line.
2) Set brightness sharpness, contrast and color control to
minumum position (Zero beam).
3) Connect accurate high voltage meter to CRT anode.
The reading should be 24.4kv(28.6kv)
DTQ-14 ----- : 22.6kv ~ 24.6kv
(
DTQ-20 ----- : 26.1kv ~ 28.8kv
If a correct reading cannot be obtained, check circuitry for
malfunctioning components.
6. X-RADIATION PROTECTION C I R C U I T TEST
When service has been performed on the horizontal
deflection system, high voltage system or B+ system, the
X-RADIATION protection circuit must be tested for proper
operation as follows:
)
1) Operate receiver for at least 15 minutes at 120V AC
line.
2) Adjust all customer controls for normal picture and
sound.
3) Check the voltage of D401 cathode. It's voltage
should be about 22V DC.
4) Connect the cathode of diode D302 and D401 through
a 2.7K ohm, 1/4W Resistor(R313).
5) To start operation, remove the resistor and touch the
cathode of D401 to chassis ground with a short clip
lead (Remove short clip lead as soon as the set
operates again with normal picture).
6) If the operation of horizontal osc. does not stop in step
The circuit must be repaired, before the set is returned
to the customer.
7. CRT GRAY SCALE ADJUSTMENT
1) Tune in an active channel.
2) Set the COLOR control to minimum.
3) Turn the SCREEN control (on T402 fully counter-
clockwise.)
4) Rotate the RED, GREEN and BLUE BIAS controls
(R971, R972, R973) counterclock wise from the
maximum, set them to the position where notches in
the knobs become parallel to the surface of P.C.
Board.
5) Set the GREEN and BLUE DRIVE controls (R975,
R974) to the mid position.
6) Turn the service switch SW20 (Service Position) on
the CRT board.
7) Rotate the SCREEN control (on T402) gradually
clockwise until the second horizontal line following the
first line appears slightly on the screen. Then turn fully
counterclockwise the two BIAS controls corresponding
to the colors of the first and the second horizontal
lines to eliminated the lines.
8) Set the SCREEN control to the position where the
third horizontal line lights slightly on the screen.
9) Adjust the two BIAS control set to the minimum in item
7) above to obtain the slightly lighted horizontal line in
the same levels of three (red, green, blue) colors. (The
line should be white if the BIAS controls are adjusted
properly.)
10) Turn the service switch SW20 again (Normal position
on the CRT board.)
11) Press PICTURE-SEL, P-UP and set the brightness
and contrast controls to the maximum.
12) Adjust the BLUE and GREEN DRIVE control to obtain
proper white-blanced picture in high light areas.
13) Using P-SEL, P-DN key, set the brightness and
contrast controls to obtain dark gray raster. Then
check the white balance in low brightness. If the white
balance is not proper, retouch the BIAS controls and
DRIVE controls to obtain a good white balance in both
low and high light areas.
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