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VC-483GS,GB,N
12) Still Preset Adjustment
1: Playback a self-recorded tape. Set the still track-
ing control at the clickstop.
Y/C PLAYBACK CIRCUIT ADJUSTMENT
e Test Point Layout
TP3IO
_TP309
TP308
tpaia
@
cG
OL4ol
e Playback preamplifier adjustment
Caution:
Do not perform this adjustment unless it is required
as after replacement of the upper drum or IC301.
1. Load the sweep tape.
2. Select play mode.
3. Observe waveform at TP308 with an oscilloscope
(with external trigger at TP309).
. Adjust each channel by the following procedure.
1) Adjust R333 (R339) to bring the peak to the
highest level.
2) Adjust C322 (C328) to bring the peak to 4.8
MHz.
3) Adjust R333
(R339) to make the ratio of 3
MHz to 4.43 MHz to 1:1.
4) Load the alignment tape and check that pic-
ture is reproduced properly.
4
Note:
If the sweep tape is not available, playback alignment
tape and make adjustment with C322, C328, R333,
and R339 to remove flickering and dark spots. Then,
by recording signal and reproducing it, check that
operation is proper.
2. Select still play mode.
Adjust R788 so that the noise bar is in blanking
time.
CF
ae
Fa
|
@ 1P404
1502
Crps02
e@
R518
TP504@
TP503@
@tTP202
@TP204
O
Figure 45
4.43MHz
mn
aig
Figure 46
Play the alignment tape. Select the still mode and
adjust C330 and R349 to remove flicker and dark
spots.
APC adjustment
1) Select play mode and playback the alignment tape
(step wave).
2) Connect 22 Kohms across TP502 and TP504.
3) Connect a frequency counter to TP501.
4) Adjust C511
(APC ADJ) so that the frequency
counter reads 4.433619 MHz (+10 Hz).
Playback video signal level adjustment
Note:
Leave VIDEO OUT open.
1. Select play mode and playback the alignment tape
(step wave).
24
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