Chassis E9-service manual ADJUSTMENT
30. VOLTAGE FOR PICTURE TUBE BEAM FOCUSING �
ADJUSTMENT CONDITION
Switch the colour TV with STOP key on remote controller to normal mode of operation. Connect signal with Philips test picture to antenna connector. �
ADJUSTMENT ACTIVITY AND RESULT OF SETTINGS
With potentiometer for focusing voltage adjustment on HV transformer set such value of voltage, that gives sharp picture on entire surface of the screen. Sharpness should be equal in corners and in centre of the screen.
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31.
VOLTAGE OF SECOND GRID OF UG2 PICTURE TUBE
Required instruments: � oscilloscope, � oscilloscope probe 100:1; � Cp=2,5pF (oscilloscope setting 0,5V/div; 5ms/div: ext. actuation with vertical time basis of TV set). Procedure: � To antenna connector connect signal with Philips test picture. � With oscilloscope probe search on video output stage for the cathode of picture tube on which video signal has highest voltage level of black (oscilloscope setting: 0,5V/div; 20 us/div: int. triggering). The probe should remain connected to this cathode. � Change the setting of oscilloscope to 5ms/div and ext. Triggering with vertical time basis of TV set and on oscillogram search for measuring "ABS" impulse (automatic black point stabilisation). � To antenna connector of TV set, which is switched on and operates in service mode, connect VF signal source with PHILIPS test picture and with 1kHz modulated sound carrier.
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With potentiometer for second grid voltage adjustment on HV transformer set such value of »ABS« pulse to voltage 130±2 V.
ABS pulse 130V 0V
32.
REFERENCE OSCILLATING CIRCUIT OF SOUND DEMODULATOR
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Connect oscilloscope probe IC525 to connector 12.
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Rotating the core of L521 coil set min. content of video signal.
