Philips 286NS-05, Руководство по обслуживанию

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8 Electrical adjustments
23 Comet
8 Electrical adjustments
8.1 Adjustments on the 110 module panel
1. Horizontal amplitude: Is adjusted with potentiometer
R3924
2. Vertical centring: Is adjusted with potentiometer R3921
3. Picture height: Is adjusted with potentiometer R3903
4. East-west correction: Is adjusted by potentiometer R3913
5. Horizontal centring (main pcb):Is adjusted with
potentiometer R3129 on the main PCB
6. Focusing: Is adjusted with the focusing potentiometer in
the line output transformer
7. AFC
–
Adjustment of the AFC and picture demodulator (all
versions).
– Select a non secam L/L' system in the SDAM mode
(negative modulation). Switch the tuner to HIGH BAND
(pin 11 of tuner 1100 grounded). Connect a pattern
generator to pin 17 of the tuner via a capacitor of 4.7nF
and put a 82W resistor from the output of the generator
to ground. Connect a DC voltmeter to pin 44 of IC7100.
Adjust coil 5100 to get 3V5 on pin 44 of IC7100.
– The signal of the generator has to be 38.9 MHz.
– Adjustment of the AFC and picture demodulator.
(BAND 1 L. France versions only).
– Same story as a) only the frequency of the generator
has to be 33.9Mhz with positive modulation.
8. RF AGC
9. If the picture of a strong local transmitter is reproduced
distorted, adjust potentiometer R3130 until the picture is
undistorted.
or: Connect a pattern generator (e.g. PM5518) to the aerial
input with RF signal amplitude = 1mV. Connect a
multimeter (DC) at pin 5 of the tuner. Adjust R3130 so that
voltage at pin 5 of the tuner is 8V5 +/- 0V5 DC.
8.2 Adjustments on the CRT panel
VG2 cut-off points of picture tube
Apply a black CVBS signal at the input pin 20 of scart. Adjust
the brightness in order to have 1.6V during the line at the R,G,B
outputs of the BIMOS pin 18,19,20 of IC7100. Put
potentiometers R3326, R3316 and R3306 to the minimum
value (maximum voltage on the CRT cathodes). Adjust now
VG2 till the colour that luminates first is not visible anymore.
Adjust now the other two potentiometers in such a way that
they just don't luminate.
Potentiometer R3308 should always be in the mid-position.