Service manual

18
VL-A111U/AH131U
VL-AH151U/AH161U
5-4-4. Adjusting the Tu guide
After replacement of Tu guide preset and adjust the height.
(1) Tu guide height presetting
(Figure 6)
Adjust the height from the upper surface of mechanism chassis to the
upper surface of lower flange with the aid of jig.
(2) Adjusting the Tu guide
(Figure 7)
1 Playback the alignment tape (VR2ABOPS).
2 Check that the tape runs at the same height near the capstan shaft in case of
V/S F and V/S R.
3 If the tape running position in case of V/S R is higher than the tape running
position in case of V/S F, turn clockwise the Tu guide nut.
If the tape running position in case of V/S R is lower than the running position
in case of V/S F, turn counterclockwise the Tu guide nut.
5-4-5. Checking the V/S F and R waveforms (Figure 8)
(1) Playback the alignment tape (VR2ABOPS), and set the V/S R mode. At this time
ascertain that the waveform crest pitch is kept constant for more than 5 seconds.
(2) Set the V/S F mode. At this time ascertain that the waveform crest pitch is kept
constant for more than 5 seconds.
Unless the constant pitch is obtained, execute the checks of Section 4-2, 3, and
4.
Figure 6
5-4-6. Checking after adjustment
(1) Envelope check
1 Playback the alignment tape (VR2ABOPS).
2 Ascertain that the envelope maximum to minimum ratio is 65% or more. (Figure 9)
3 Ascertain that the waveform does not change remarkably. (Figure 10)
Figure 10
E MAX
E MIN
E MAX
E MIN
65 (%)
Figure 9
A
C
C
C 1/8A
(2) Rise check
1 Playback the alignment tape (VR2ABOPS).
2 Once eject the cassette, and then load it again.
3 Set the playback mode, and ascertain that the RF waveform rises horizontally
within 2 seconds. At this time ascertain that there is no tape slackness near
the pinch roller.
4 After V/S F, R and FF/REW execute playback, and ascertain that the RF
waveform rises horizontally within 2 seconds. At this time ascertain that there
is no tape slackness near the pinch roller.
Capstan shaft
Tu guide
Tape slackness
Tu GR
Figure 11
Tension pole
Si roller
Sup tilted pole
Sup GR
Drum
Drum
Tu GR
Pinch roller
Tu guide
Tu tilted pole
Figure 12
(3) Checking the tape running
1 When the tape is played back, ascertain that tape lift and tape curl of 0.3 mm
or more do not occur at the lower flange of Si roller, upper flange of Sup GR,
upper flange of Tu GR, and upper/lower flange of Tu guide.
2 In case of V/S F and R ascertain that no curl is found at each flange.
5-4-7. Checking and adjusting the playback switching point
Refer to the description of playback switching point adjustment in section of VCR circuit adjustment.
Figure 8
abcd
a b c d
Figure 7
Nut
Capstan shaft
Pinch roller
Upper flange
Lower
flange
Height setting jig
Master plane
(JiGMP-MX7U)