akira CT-21XF9, Service Manual

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12
Model No: CT-21XF9A
Version 1.0
CIRCUIT ADJUSTMENTS
GENERAL INFORMATIONS
All adjustment are thoroughly checked and corrected when the receiver leaves the factory. Therefore
the receiver should operate normally and produce proper colour and B/W pictures upon installation.
However, several minor adjustments may be required depending on the particular location in which the
receiver is operated.
This receiver is shipped completely in carton. Carefully draw out the receiver from the carton and
remove all packing materials. Power cord into a convenient 220 volts 50 Hz AC two pin power outlet.
Turn the receiver ON. Check and adjust all the customer controls such as BRIGHTNESS, CONTRAST
and COLOUR Controls to obtain natural colour or B/W picture.
AUTOMATIC DEGAUSSING
A degaussing
coil
is mounted around the picture tube so that external degaussing after moving the
receiver is normally unnecessary, providing the receiver is properly degaussed upon installation. The
degaussing coil operates for about 1 second after the power to the receiver is switched ON. If the set is
moved or faced in a different direction, the power switch must be switched off at least 30 minutes in
order that the automatic degaussing circuit operates properly. Should the chassis or parts of the cabinet
become magnetized to cause poor colour purity, use an external-degaussing coil. Slowly move the
degaussing coil around the faceplate of the picture tube, the sides and front of the receiver and slowly
withdraw the coil to a distance of about 2m before disconnecting it from AC source. If colour shading
still persists, perform the COLOUR PURITY ADJUSTMENT and CONVERGENCE
ADJUSTMENTS procedures.
POWER SUPPLY ADJUSTMENT
CAUTION: +B voltage has close relation to high voltage. To avoid X-ray radiation, +B voltage should
be to +115V.
1. Set RV801 to the mechanical center and AC power supply to 220 ± 2V.
2. Connect a digital voltmeter to two pins of C822, and then turn on the TV.
3. Receive Philips test signal.
4.
Adjust RV81 to make the voltmeter read 115±0.5V.
HIGH VOLTAGE EXAMINATION
CAUTION: No high voltage adjustment should be done in CN-9EA chassis.
1. Connect a precise high voltmeter to the second anode of the CRT.
2. Turn on the TV and set the brightness and contrast to minimum (i.e. set beam current of the
CRT to zero).
3. The high voltage tested should be 27.5 ± 0.5KV.
4. Set the brightness to minimum or maximum, and ensure high voltage not beyond limitation of
30KV in any case.