Sharp VL-AD260U, Service Manual

Page: 17 / 97

17
VL-AD260U
5-4. ADJUSTMENT OF MECHANISM TAPE TRAVEL SYSTEM
5-4-1. Preparation for adjustment
Tape travel system (Figure 1)
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Drum
Reel
Tension pole
Si roller
Sup GR
Sup tilted pole
Tu tilted pole A
Tu GR
Tu tilted pole B
Capstan shaft
Tu guide
Pinch roller
5-4-2. Adjusting the Sup GR and Tu GR
(1) Turn the Sup and Tu guide rollers to get the flat waveform at the inlet and outlet sides.
Inlet side Outlet side
(a) Normal
(b) Inlet side
waveform is disturbed. (c) Outlet side
waveform is disturbed.
Figure 2
5-4-3. Adjusting the Si roller height
After replacement of Si roller preset and adjust the Si roller
height.
(1) Si roller height presetting
Adjust the height from the upper surface of mechanism
chassis to the upper surface of lower flange with the aid of jig.
Then lower it by 90
°
(clockwise).
Upper flange
Lower
flange
Height adjusting jig
Master plane
(JiGMP-MX7U)
Upper flange (A)
Si roller
REV mode
Lower flange (B)
Tape must be free from foldeng.
(2) Adjusting the Si roller
1 Playback the tape to set the V/SR mode.
2 Ascertain that the tape is not folded on the lower flange (B) of Si roller. (Figure 4)
If tape folding is found, turn the upper flange (A) of Si roller with the driver (clockwise) to eliminate the folding.
3 Playback the alignment tape (VR2ABOPS).
4 Adjust the Sup GR and Tu GR by the procedure described in section 4-2 above.
5 After V/S F,R perform playback so as to ascertain that the waveform rises horizontally within 2 seconds.
6 Unless the normal waveform is obtained (Figure 5), turn counterclockwise the upper flange (A) of Si roller, and repeat the step
(5) above. Repeat the steps (5) and (6) until the normal waveform is obtained. At this time ascertain that the inlet travel does
not change in the normal playback state. If any change is found, adjust the Sup GR, and redo the step (5).
Figure 3
Rise waveform
REV OK Playback
REV NG Playback
Figure 4
Figure 5
(1) Clean the tape running areas (guide poles, rollers, drum,
Capstan shaft, Pinch roller) (Figure 1)
(2) Connect the oscilloscope to the following TPs.
RF output ..... TL7410
H-SW-P ....... TL7417
GND ............. TL7413
(3) Playback the alignment tape (VR2ABOPS).
(4) Ascertain that each guide is free from remarkable curl.
(5) Ascertain that the RF waveform of inlet and outlet sides is flat
on the oscilloscope (Figure 2, (a)). Unless the waveform is
flat, (Figure 2, (b), (c)), make an adjustment as follows.