Sharp VL-AD260U, Service Manual

Page: 15 / 97

15
VL-AD260U
5-3. MECHANISM CHECKS AND ADJUSTMENTS
The description given below relates to the general field services, but does not relate to the adjustment and replacement that require
high level equipments, jigs, and technical skills.
In order to maintain the initial characteristics of the machine, it is necessary to execute the maintenance and check and to prevent
damage to tapes and other parts. For adjustments which need jigs, be sure to use the jigs.
Notes and cautions
(1) For mechanism checks and adjustments, be sure to use the AC adapter as the power supply.
(2) For running the tape, be sure to install the cassette control ass’y in advance. (If the cassette control ass’y is to be removed
subsequently after its installation.)
5-3-3. Checking and adjusting the back tension torque for playback (recording)
5-3-1. Checking the reel disk height
(1) Remove the cassette control ass’y.
(2) Taking due care not to let the master plane touch the tape running areas such as the drum and the guide rollers, position the
master plane so that the two guides (A and B in the Figure 1) are set in the holes of master plane, then properly set it in the
mechanism.
(3) Using the slide callipers or the like, check that the distance from the upper surface of master plane to the reel support surface
of the S/Tu reel disk is within the specified range. (Figure 2)
Note:
When measuring, do not apply excessive force to the reel support surface of reel disk.
(4) If the measurement is not within the specified range, replace the reel disk ass’y.
(5) Check the items (2) to (4) above in the following two modes.
a) Standby mode
b) Playback (recording) mode
5-3-2. Checking the take-up torque for playback (recording)
(1) Set the torque cassette (JiG8T-012) in position, and check in the SP-mode recording mode (tape recorded in SP mode) that
the torque at the tape taking-up side is within the standard range.
Standard of take-up torque for SP-mode recording (playback)
9
±
3 g·cm with ripples less than 4 g·cm
(If the torque ripples appear, read the center value of torque between the ripples.)
4.4
±
0.15
Reel support surface
4.4
±
0.15
Figure 2 Figure 1
(1) Checking
1) Set the torque cassette (JiG8T-012) in position, and check in the SP-mode recording mode
(tape recorded in SP mode) that the torque at the tape supply side is within the standard
range.
Standard of back tension torque for SP-mode recording (playback):
8
±
2 g·cm with ripples of less than 2 g·cm
(Torque ripple must be within 8
±
2 g·cm)
(2) Adjustment
1) If the back tension torque is not within the standard range, adjust the tension spring hooking
position. If the back tension is too high, hook the spring in the direction A. If the back tension
is too low, hook the spring in the direction B.
Note:
1. After back tension torque adjustment be sure to check the tension pole position.
A
B
A
B