Service manual

SERVICE MANUAL
CIRCUIT ADJUSTMENTS
1. General Description
All adjustments are thoroughly checked and corrected before the TV outgoing. Therefore the TV
should operate normally and deliver proper colour pictures upon installation. However, several minor
adjustments may be required depending on the particular location where the TV is operated.
This TV is shipped completely in carton. Carefully take out the TV from the carton and remove all
packing materials. Connect the power cord into a 120V AC, 60Hz two-pin power outlet. Turn on the
TV. Check and adjust all the customer controls such as brightness, contrast and colour to obtain
natural colour pictures.
4. Automatic Degaussing
A degaussing coil is mounted around the CRT so that external degaussing after moving the TV is
generally unnecessary providing it is properly degaussed upon installation. The degaussing coil
operates in about 1 second after power on. If the set is moved or faced to a different direction, the
power switch must be switched off for 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
screen, the sides and front of the TV and slowly withdraw the coil to a distance of about 2m before
unplug it. If colour shading still exists, perform the Colour Purity Adjustment and Convergence
Adjustment procedures.
3. Supply Voltage Adjustment
Caution: +B voltage has close relation to high voltage. To avoid X-ray radiation, +B voltage should be
+135V.
1) Set AC power supply to 120±2V.
2) Connect a digital voltmeter to two pins of C845, and then turn on the TV.
3) Receive Philips test pattern signals.
4) The voltmeter should read 135±0.5V.
4. High Voltage Inspection
Caution: No high voltage adjustment should be done in the 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 28.8±0.8KV for 29” and 26.5±0.8KV for 25”.
4) Set the brightness to minimum or maximum, and ensure high voltage not beyond limitation of 31KV
in any case.
5. Focus Adjustment
1) Use the remote control to set the contrast to maximum and the brightness, chroma to medium.
2) Set H. V. lines near Philips pattern center to thinnest with the FCB on the FBT. After finishing
adjustment, ensure that no poor focusing exists near the center or around of the frame.
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