Daewoo DV-K784N-JJ, Руководство по обслуживанию

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6. Playback Phase Adjustment (Fig. 14)
Test Points: PT01 Pin3 Main
Video Out Jack Rear Panel
Observe: Oscilloscope
Adjust: VR595 (PG Shifter) Main
The Phase Generator (PG) Shifter determines the video head
switching point during playback. Wrong adjustment of the PG
shifter may cause the head switching noise in the picture and/or
vertical jitter.
1). Play Back the Alignment Tape (color bar signal or mono-
scope signal).
2). Connect the channel-1 scope probe (1V/div.: 50psec/div.) to
PT01 pin3. Trigger the scope on channel-1.
3). Connect the channel-2 scope prove (1V/div.) to the video out
jack.
4). Set the scope to (–) slope an adjust the PG Shifter control
(VR595) so that the trailing edge of the SW30Hz pulse is
placed 6.5H±0.5H(horizontal) lines before the start of the
vertical (horizontal) lines before the start of the vertical sync
pulse.
7. Linearity Adjustment (Fig. 15)
Test Points: CTL Pulse Test Pin Path Adj. Fixture
Envelope Test Pin Path Adj. Fixture
Observe: Oscilloscope
Adjust: VR Control Path Adj. Fixture
S/T Guide Rollers Transport Mech.
1). Connect the Path Adj. Fixture to PT01 on the Main circuit
board.
2). Play back the Alignment tape (color bar signal).
3). Connect the channel-1 scope probe to the CTL pulse test pin
on the Path Adj. Fixture.
4). Connect the channel-2 scope probe to the envelope test pin
on the Path Adj. Fixture. Externally trigger the scope using
the SW pulse test pin on the Path Adj. Fixture.
5). Adjust the VR Control on the Path Adj. Fixture so the enve-
lope (FM) signal of the Aligment tape is maximum.
6). Adjust the S/T guide rollers so that the envelope (FM) signal
waveform at the entrance and exit sides are as shown
in Fig. 1
8. Fine Adjustment of Envelopes at Drum Entrance/Exit
Parts (Fig. 16 & 17)
Test Points: CTL Pulse Test Pin Path Adj. Fixture
Envelope Test Pin Path Adj. Fixture
Observe: Oscilloscope
Adjust: VR Control Path Adj. Fixture
S/T Guide Rollers Transport Mech.
1).Connect the Path Adj. Fixture to PT01 on the Main circuit
board.
2). Play back the alignment tape (color bar signal).
3). Connect the channel-1 scope probe to the CTL pulse test pin
on the Path Adj. Fixture.
4). Connect the channel-2 scope probe to the envelope test pin
on the Path Adj. Fixture. Externally trigger the scope using
the SW pulse test pin on the Path Adj. Fixture.
5). Adjust the VR Control on the Path Adj. Fixture CCW and
CW and confirm that the envelope waveform changes uni-
formly and remains flat throughout the overall range.
6). If the envelope is not uniform, slightly adjust the S/T Guide
Rollers to correct the envelope.
Fig. 13 X-Axis Position Adjustment
Fig. 14 Playback Phase Adjustment
Fig. 15 Linearity Adjustment