ADJUSTMENTS (continued)
For authorized personnel only
3.4 Aperture correction
Apply a video sweep signal to
INPUT 1.
Connect the probe of the oscilloscope to TP20.
Enable the aperture correction by pressing
APT
on the keyboard (green
LED
lights up).
Adjust with P12 the aperture correction signal for equal level at the bottom of the sync pulse.
3.5 TDA 4510 adjustments
Apply a PAL colour bars signal to
INPUT
1.
Connect the probe of the oscilloscope to TP22 (R-Y signal).
Make a short-circuit with J5
Adjust C62 for zero beat.
In case the decoder board has an ACC/ ON-OFF board, make sure that the switch SW1 is set in
the MOD.OFF position.
Connect the probe of the oscilloscope to TP23 ( B-Y signal ).
Adjust L7 for correlation of two successive B-Y lines.
Adjust P2 for correct matching of the direct and delayed signal.
3.6 ACC ON/OFF Circuitry
3.6.1 ADJUSTMENT OF THE LOOP-AMPLIFIER
Set switch SW1 in the MOD.ON position. The ACC-unit is now active.
Apply a colour-bars signal at the input of the decoder.
Connect a dc-voltmeter to TP1 of the ACC-unit and adjust P5 for 750 mV( +/- 20mVdc).
3.6.2 PAL BURST PHASE
Connect an oscilloscope to TP23 on the main decoder board ( B-Y output ).
Make a short-circuit of pin 3 and 4 of the delay line DL2.
Adjust P3 on the ACC-unit for correlation of two successive B-Y lines on the scope.
3.6.3 PAL CONSTANT BURST AMPLITUDE
Set switch SW1 in the MOD.OFF position and measure on TP23 the B-Y amplitude.
Set switch SW1 in the MOD.ON position and adjust P1 for the same B-Y amplitude.
3.6.4 COLOUR KILLER LEVEL SETTING
Attenuate the input signal to the level on which you want of have colour killing.
(e.g. -10dB ). Set P6 so that colour is just switched-off.
3.6.5 CONTROL OF THE NON-ACC OPERATION
Connect an oscilloscope to the green cathode of the CRT.
Attenuate the input signal with 10 dB or increase the input signal with 6dB ( no 750hm
termination ) and check if the saturation remains the same.
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