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GUIDE ROLLER ADJUSTMENT
e Video Tape Setting Procedure
1. Remove the upper cabinet.
2. Place an adjustment tape in the cassette housing.
3. Connect the power cord, monitor output cord and
video input cord in their proper positions.
4. Connect CH-1 of an oscilloscope to the RF enve-
lope output, and CH-2 to switching pulse T, P.
5. Press the PLAY button to enter the PLAY mode.
e Adjustment
1. The guide roller setscrews should be tightened as
much
as possible without using unreasonable
force, using the guide roller adjustment flat-bladed
screwdriver.
2. Trigger with a switching pulse and observe the
envelope (Figure 27).
3. Adjust the height of the guide rollers while watch-
ing the envelope so that the tape runs along the
drum lead. Whether the video tape is above or be-
low the helical lead will be shown in the wave-
form represented by the envelopes in Figures 28,
29.
Envelope
(TP-308)
Oscilloscope
CH-1 waveform
TRACK
TRACK
Oscilloscope
CH-2 waveform
Switching Pulse.
(TP-309)
Figure 27
a. Envelope waveforms where video tape is floating
above the helical lead position
~
Floating
A little way
To some extent
Considerably above
Supply side
(drum entry)
Take-up side
(drum exit)
Figure 28
18
b. Envelope waveforms
where video tape is sup-
pressed too heavily to the helical lead posiiton.
Slight
Medium
Heavy
Supply side
(drum entry)
Take-up side
(drum exit)
Figure 29
4. Fine adjust the height of the guide rollers while
watching the envelope so as to make the envelope
flat.
Adjust so that even altering the tracking control has
not much adverse effect on the flatness.
5. Adjust so that when the tracking control is shifted
(when the tracking control is moved and A of the
RF waveform begins to decline), the ratio between
A and B in Figure 30 is better than A:B =
10:7.
6. Adjust the playback switching point, as described
in "Electrical Adjustment
—
Playback Switching
Point Adjustment".
7. Using an auto video recording/playback tape, record
and play a color bar to check that the envelope is flat.
8. After adjustment, finally tighten the guide roller set-
screws.
9. After this, check the RF envelope again.
Entry
Exit
MAX
~
|
|
A:B=10:7
Figure 30
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