Zanussi 22ZT907, Service Manual

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Adjustment of reference circuit
1
Connect the oscilloscope's probe to video output (A
Connect the IF signal (complete of modulated audio) at 10 level
on TP 1.
Adjust L44 for minimum amplitude of demodulated signal,
corresponding to the best response transients or to 2 T pulse.
Adjust the
6 MHz
trap and the audio input filter
Adjust and L48 for lowest output of 6 MHz signal present in
Adjustment of audio quadrature coil
Move the oscilloscope's probe to pin 8 TBA 120 U audio output).
Give a max. 12V bias to the volume control terminal A 2.
Connect a resistance between pin
13
of TBA 120 U and the
and read the DC voltage.
Disconnect the 10 resistance.
Adjust L47 until the DC voltage corresponds again to value measured
previously.
Audio adjustment
Move the oscilloscope probe to terminal A 3.
Maintain on the TP 1 the IF signal with modulated audio carrier.
Adjust P 2 so as to obtain on the A 1 terminal the signal
VA
3
2.2 0.2 vpp = 0.78 0.07 V RMS.
AFC adjustment
Bias the AFC output by means of two 100 resistances
towards
and the other towards earth.
one
Connect a voltmeter to AFC output pin A 12.
Adjust L45 for an intermediate value (approx. 2V) in range of
values that go from to 0 V.