Back Tension Torque Check And Adjustment In Record (Playback) Mode; Checking Of Supply S Reel Base No-Load Torque; Checking Of Loading Back Tension - Sharp VL-PD3U Service Manual

L-PD3U
7-4. Back tension torque check and adjustment in record (playback) mode
1 AC adapter used, with cassette controller assembly
1
(1) Checking
Tension roller position (S guide standard)
Set the torque cassette (SD-l 015), and make sure in the SP record mode that
the supply side torque is within the standard shown below (or in the playback
mode for the tape on which the signal has been SP-recorded).
<Standard>
(If torque ripple exists, read its center value.)
0.7 + 0.1 mN*m (7 + 1 gem)
(2) Adjustment (Fig. 4)
If the value is out of standard range, adjust, using the screw 1 shown in Fig. 4.
1. Loosen the screw 2 slightly.
2. Adjust to turning the screw 1. When back tension is too high, turn the screw
1 counterclockwise (CCW).
When back tension is too low, turn the screw 1 clockwise (CW).
3. After adjustment fix the angle with the screw 2. (At this time take care so as
to prevent excessive tightening.) Apply Screw Lock to the screw 1.
<Caution>
Screw tightening torque: 0.04Nm (0.4kgcm)
Fig. 4. Check (tape exists)
7-5. Checking and adjustment of tension roller position in
record (playback) mode
Tension roller position (S guide standard)
DC3V, without cassette controller assembly (Independent Mechanism)
(1) Checking
Before winding the 60-min. tape make sure that the tension roller is in the same
position as S guide as shown in Fig. 4.
If not, take out the tape and adjust in the following procedure.
(2) Adjustment (Fig. 5)
1. Set the playback mode without loading the tape.
2. Loosen the screw 3 slightly (to such an extent that the tension band holder
4 can be moved).
3. If the tension roller is inside from the specified position, shift the tension
band holder 4 in the arrow @ direction. If the tension roller is outside, shift
the tension band holder in the arrow @ direction, and fix with the screw 3.
(Proper shift must be 0.2 to 0.6mm outside from the specified position.)
4. Check the position by the procedure described in item (1) Checking above.
5. If the position is not specified position, adjust again.
7-6. Checking of supply S reel base no-load torque
DC3V,
without cassette controller assembly (Independent Mechanism)
Fig. 5. Position adjustment
(tape does not exist)
(1) Remove the cassette controller assembly, then apply DC3V to the loading
motor and put the system into L. start mode (refer to 9-l).
(2) Move the swing arm toward the Tu reel base side.
Be careful not to prevent damage to the gears and other parts all this while. (Fig.
6)
(3) Set a back tension measurement reel hub on the S reel base.
(4) Using a dial tension gauge, pull the string in the A direction, then confirm that the
tension is within the standard.
<FF back tension standard>
(If the tension fluctuates, read its center value.)
20mN or less (2.0gf or less)
7-7. Checking of loading back tension
j DC3V. without cassette controller assemblv (Independent Mechanism)
1
(1) Remove the cassette controller assembly, then apply DC3V to the loading
motor and put the system into L. start mode.
(refer to 9-l)
\ Move theswingarm
(2) Move the swing arm toward the S reel base side. Be careful not to prevent
damage to the gears and other parts all this while. (Fig. 7)
(3) Set a back tension measurement reel hub on the Tu reel base.
(4) Using a dial tension gauge, pull the string in the A direction, then confirm that
the tension is within the standard.
Fig. 6. S reel base no-load torque
measurement method
7-2