Advertisement
SAFETY
PRECAUTIONS
: An isolation transformer
should be connected
in the power line between the receiver and the AC
line before any service is performed on the receiver.
Q
X-
RADIATION
PRECAUTION
The primary
source
of X- RADIATION
in television
receiver is the picture tube. The
picture tube is specially constructed
to limit X- RADIATION
emissioh.
For continued
X- RADIATION
protection,
the replacement
tube must
be the same type as the original
including suffix letter. Excessive high voltage may
produce potentially
hazardous
X-
RADIATION.
To avoid such hazards, the high voltage must be maintain within specified
limit.
Refere to this service manual
for
specific high voltage limits. If high voltage exceeds specified limits, take necessary corrective action. Carefully follow the instructions
for + B1 volt power supply adjustment,
and high voltage check to maintain the high voltage within the specified limits.
AGC ADJUSTMENT
NOTE; Do not attempt this adjustment
with weak signal.
1. Tune the receiver to the most clearest (or strongest) VHF
station in your area. Set the brightness and the contrast
controls to maximum. Set the colour control to minimum.
2. Set the AGC (VR101 ) control to mid- range.
3. Turn AGC control in direction which causes the snow to
appear, then in the opposite direction until the snow just
disappears.
SUB BRIGHTNESS
ADJUSTMENT
1. Connect a DC meter between
"TP- W' (positive lead) and
"TP- G" (negative lead) on the main unit.
2. Receive the circular pattern.
3. Set the brightness to maximum and the contrast to
minimum.
4. Adjust the sub brightness control (VR211
)
for 0.2V(14"
&1 6") / 0.3V(20").
NOTE: If the picture tube replaced,
check the sub-
brightness adjustment.
VERTICAL SIZE ADJUSTMENT
1. Tune the receiver to the monochrome
circular
pattern.
2. Adjust the vertical size (VR451 ) control for full scan.
HORIZONTAL
CENTER ADJUSTMENT
1, Tune the receiver to the monochrome
circular pattern.
2. Set the brightness and the contrast to maximum.
3. Adjust the video phase (VR411 ) for optimum horizontal
center position.
B1 POWER SUPPLY ADJUSTMENT
1. Connect DC meter to
"TP- B" and the ground.
Set the + B1 adjustment
control (VR351 ) to mid-range.
2, Set the brightness and the contrast to minimum.
Tune the receiver to an active channel and the synchronize
picture.
3. Adjust+
B1 adjustment
control for 130 f 1.0 volt DC.
TUNING DISPLAY WIDTH ADJUSTMENT
1. Tune the receiver to the monochrome
circular pattern.
2. Press and hold the recall button of the remote control unit
for more than 2 second.
3. Press"1"
button of the channel selector of the remote
control unit, and the tuning bar is displayed on the screen.
4, Adjust VR71 O for optimum tunning bar width.
5. Press recall button, and the tuning bar is disappears.
GREY SCALE AND TRACKING ADJUSTMENT
1, Tune the receiver to the monochrome
circular pattern.
2, Set the brightness and the contrast
to maximum,
the colour to minimum.
3. Set the service switch (SW251 ) at the service side.
4. Set the drive volume
(VR602 and VR612) at their
mechanical
center,
5. Set the bias volume (VR601, VR621 and VR611 ) to
minimum. (fully counter clockwise).
6. Turn the screen volume
to obtain just visible one
coloured line.
7. Adjust each bias volume (VR601 - blue, VR621 - green
and VR611 -red) alternately
until a dim white line
produced.
8. Set the service switch (SW251 ) at the normal side.
9. Adjust the drive volume (VR602- blue and VR612- red)
alternately to produce normal black and white picture.
10,Check for proper grey scale tracking at all brightness
levels.
%d
NOTE : If grey scale adjustment
is made after picture tube
replacement,
check high voltage and sub- brightness
adjustment.
~OLOUR ADJUSTMENT
(PAL)
leceive the colour bar pattern.
Jet the the brightness and the colour to maximum,
he contrast to minimum.
I
ADJUST
REMARKS
—
1
Connect 1
1R281 ,T28
I
—
2
L211
?oscilloscope
to TP8C=IC851
PIN 17
Adjust VR281 ,T281 to obtain each 1H
waveform(amplitude)
for same as shown
below.
\lH~
+'
d.e
n.
w
#;~:
~; ~
,, ,,,,,
....
j;.
.,,, , ,,,,
de
min.
Adjust L211 to obtain proper
waveform as
shown above.
FOCUS ADJUSTMENT
Adjust the focus control on the left side of the chassis for well
scanning lines.
HORIZONTAL
WIDTH AND HIGH VOLTAGE CHECK
.
1.
Tune the receiver to the circular pattern.
2. Set the brightness and the contrast to maximum.
3. Cut or shorten the jumper lead wire- AJ1. If AJ1 shorted,
horizontal width increases. If AJ1 cut, horizontal width
decreases,
4, Connect a high voltage probe to anode lead
of the picture
tube.
5. High voltage must
be between 20-22KV(14"
16"),
24- 26KV ( 20").
NOTE:
If the picture tube replaced, check the high voltage
—3—
Advertisement
