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Service Control Adjustments
.
1
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.
.-
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
emission.
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.
Refer 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.
NOTE; Do not attempt this adjustment
with weak signal.
(1) Tune the receiver
to most
clearest
(or strongest)
VHF
station
in your
area.
Set the
brightness
and
contrast
controls to maximum.
Set the colour control to minimum.
(2) Set AGC (VR1 01) control to mid- range.
(3) Turn AGC control in direction which causes snow to appear,
then in the opposite direction until the snow just disappears.
(1) Connect a DC meter between
"TP- H" (positive lead) and
"TP - G" (negative lead) on main unit.
(2) Receive the circular pattern.
(3) Set the brightness to maximum and contrast to minimum.
(4) Adjust the sub brightness control (VR211) for 0.2V(1 6").
NOTE: If the picture tube replaced,
check the sub-brightness
adjustment.
(1) Receive the monochrome
circular pattern.
(2) Set the brightness and contrast to normal.
(3) Adjust VR411 for optimum horizontal center position,
F7Fw''z"n'a'cen'er
(1) Receive the monochrome
circular pattern.
(2) Set the brightness and contrast to normal.
(3) Vertical centering can be adjusted by switching SW451.
rtical center
(1) Receive the monochrome
circular pattern.
(2) Set the brightness to normal and contrast to maximum.
(3) Adjust the focus control on the F.B.T for the best focus on
the screen center.
Receive PAL colour bar pattern. (see Figl on the page2.)
Set the brightness, colour and contrast to maximum.
I ADJUST. ]
REMARKS
Connect the oscilloscope
to TP6B on CRT unit
2
I-21 1
Adjust L211 to obtain proper waveform as shown
above.
I
(1) Receiver 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.
(1O)Check
for proper
grey
scale tracking
at all brightness
levels.
NOTE: if the grey scale adjustment
is made after picturetube
replacement,
check high voltage
and sub - brightness
adjustment.
(1) Receive the monochrom
circular pattern.
(2) Set the brightness and contrast to maximum.
(3) If the picture is too wide or narrow, cut or short the "AJ1" on
the main
unit . When
AJl
is shorted,
the horiz.
width
increase. When AJl is cut, the horiz. width decrease.
(4) Connect a high voltage probe to anode lead
of the picture
tube.
(5) The high voltage must be between 20- 22KV(1 6").
NOTE: If the picture tube is replaced, check the high voltage.
--
The horiz. width adjustment
affects the high voltage and
–3–
sub brightness.
Therefore,
recheck the sub brightness
and the high voltage.
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