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Service Adjustments
Gray Scale Adjustment
1. Receive the mono-chrome circular pattern.
2. Set the picture mode to "NORMAL" mode by
pressing the IMAGE button on the remote control.
NORMAL
3. Set the service switch (SW701) on the CRT board to
"SERVICE" position.
4. Set RED (VR704) and BLUE (VR705) drive controls
to mid position. Set BLUE (VR703), GREEN (VR702)
and RED (VR701) bias controls to minimum (fully
counterclockwise).
5. Turn the SCREEN control on the F. B. T. to obtain just
visible one coloured line.
6. Adjust each bias control alternately until a dim white
line produced.
7. Set the service switch (SW701) to "NORMAL"
position.
8. Adjust RED and BLUE drive controls alternately to
produce normal black and white picture in highlight
areas.
9. Check for proper gray scale at all brightness levels.
Note: If the gray scale adjustments is made after pic-
ture tube replacement, check the brightness level
adjustment.
Service information
Protection Circuit
This TV set has a built-in power supply protection circuit.
It is provided to protect the TV set in case of a power supply circuit malfunctions. When something abnormality
occurs during TV reception, the TV set goes to the stand-by mode.
When an abnormality occurs during TV reception, it causes pin 41 of the CPU to go continually Low(less than
0.75V) for about one second. The CPU detects that this has occurred and outputs the signal from pin 1 to
switch off the power oscillation circuit.
Releasing the protective circuit and restoring power supply
To release the protective circuit and restore power supply, turn the power to the TV set OFF and then ON again
via either the main power switch or the ON-OFF button on the remote control. This will work only if the power
supply trouble was temporary. If there is permanent trouble such as a damaged circuit, power cannot be
restored and the circuit will have to be repaired.
Q431
HORIZ.
DRIVE
TP-G
Grey Scale Adjustment
VR703
BLUE BIAS
VR702
GREEN BIAS
VR701
RED BIAS
VR705
BLUE DRIVE
VR703
RED DRIVE
(CRT BOARD)
-10-
VR465
H-WIDTH
T451
VR510
F.B.T.
V-SIZE
L430
FOCUS SCREEN
TP-H
(MAIN BOARD)
Q701
B-OUT
K701
CRT SOCKET
Q703
G-OUT
Q705
R-OUT
K7Y1
SW701
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