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Adjustment Procedures
7970B/7970C
1
RETAINING RING
2
0.005 WASHER
3.
CRESCENT WASHER
4
0.010 WASHER
5
ROLLER ASSEMBLY
G
RETAINING RING
7.
BRASS NUT
8
CRESCENT WASHER
9.
TAPE ROLLER SHAFT
7970-C-038
Figure 5-1. Tape Roller and Bearing Assembly, Exploded View
b. When the arm is within
1/8
inch of the bumper
stop, the microswitch must operate. Also there must be
further positive movement of the switch arm between the
point at which the switch closes and the tension arm is in
full stopped condition against the rubber bumper.
c. Verify that all screws are tight prior to final con-
firmation of "a" and "b." Repeat adjustment for all three
limit switches. If background noise permits, switch opera-
tion can be checked audibly; otherwise connect a suitable
ohmmeter across the switch terminals. If ohmmeter is used,
verify that power is not applied to the tape unit.
5-15.
WRITE ENABLE SWITCH.
5-16.
The write enable switch must be positioned to as-
sure clearance when operated with a reel that does not have
the write enable ring installed (reel is file protected) and to
assure both retraction and operating clearance when used
with a reel that has the write enable ring installed. These
conditions will be established when the proper dimensional
relationships exist between the write enable sensing finger
and the outer face of the reel turntable. To obtain these re-
quired dimensional relationships, perform the adjustment
procedure in the order indicated. (See figure 5-2.)
a. Loosen switch Sl mounting screws.
5-2
b. Manually place the sensing finger even with the
edge of the turntable. With power removed, adjust the posi-
tion Sl until an audible click indicates that switch Sl is
closed.
c. Tighten switch Sl mounting screws.
d. Apply power and manually place the sensing finger
even with the turntable. Verify that the solenoid energizes
and completely retracts the sensing finger.
e. Adjust the reel turntable flange diameter clearance
as follows:
5-17.
(1)
Loosen write enable assembly mounting
screws.
(2)
Position the write enable assembly so that the
sensing finger will clear the reel flange diam-
eter throughout solenoid travel.
(3)
Tighten write enable assembly mounting
screws.
REEL RETAINING KNOB.
5-18.
This adjustment is made during manufacture but
may require some correction during the life of the tape unit.
Part 2
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