Service Adjustments - Sanyo C21LB25S Service Manual

Service Adjustments

Following adjustments are not required to readjust when replacing the memory IC.
MAIN BOARD
F.B.T. T401
FBT
FOCUS VR
(Upper side)
FOCUS ADJUSTMENT
(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 centre.
HORIZ. WIDTH AND HIGH VOLTAGE CHECK
(1) Receive the monochrome 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 AJ1 is shorted, the horizontal width
increase. When AJ1 is cut, the horizontal width decrease.
Important note: If the AJ1 is cut, it's gap must be more than 5mm to prevent sparks.
AJ1
more than 5mm
(4) Connect a high voltage probe to anode lead of the picture tube.
(5) The high voltage must be 14"=21KV ± 1KV / 20",21"=25KV ± 1KV /29"=26.5KV ± 1KV and less than
14"=25KV / 20",21"=27.5KV / 29"=29.5KV at 0 beam current (Brightness and contrast minimum setting).
Note: If the picture tube is replaced, check the high voltage. The horiz. width adjustment affects the high voltage.
Therefore, re-check the high voltage.
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 33 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 8 to
switch off the power supply lines.
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.
Q432
HORIZ. OUT
AJ1
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