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At this time, with the forw ard-reverse magnet de-energized, the forw ard-
reverse armature should be centered, whether the moving coil is in a start or a
stop status.
5.
The final start-stop adjustment is checked by the use of the scope and should
be set at 4. 5 ms to 5. 5 ms (Figures 24, 25).
in both directions with the scope.
changing the position of the stop capstans in the proper direction, is the proper pro
cedure to obtain optimum operation.
after any change in the stop capstan setting and should not be changed more than
. 003" to obtain the proper timings.
not strike the drive capstans.
moving pulley and the drive capstans on the non-driving side.
Check in both directions.) When these times are not within limits with the above ad
justments, the condition indicates some trouble from a binding or worn linkage, an
error in making the recommended adjustments, or tube trouble in either the moving
coil driving circuits or the forw ard-reverse magnet inverters. Refer to section 19
for operation of the tape tester.
1 5.8.5
Tests for Moving Coil, Forward-Reverse Magnet, and Stop-Capstan
The following tests may be made to check adjustments:
1. With the above adjustments made, the capstan motor running, and no tape
between pulleys, the moving pulley (which is not being driven) should not strike its
drive capstan as the pulley moves from a stop position to a neutral position.
2.
Check in the forward condition by moving the motion control switch from
stop to forward several times.
should not rotate appreciably.
striking the drive capstan.
without having interfered with the capstan.
capstan motor plug and repeat the above test.
rotation, there is no interference.
To check in the reverse condition, interchange the edge connectors In and lp and
move the motion control switch from stop to reverse several times.
pulley on the right should not rotate appreciably.
The malfunction of both moving pulleysT driving at once may be observed by
another procedure as follows:
Load a tape with all ones written in one channel into the machine and observe the
output of the read-write head in that channel.
fairly steady value if conditions are normal.
non-driving side is striking its drive capstan the tape will tend to stop momentarily.
This stopping causes the signal envelope observed to drop sharply or even reverse
and then return to normal (Figure 24) 0
15. 8.6
Start and Stop Time
The following procedure may be used to check start and stop time of the tape
unit:
1. Use a reel of tape with ones written continuously on the center track.
2,
Start and stop the tape unit by using the customer engineer manual control
box without the tape unitT s being selected, or by using the tape drive tester.
The start-stop times must be checked
A minor adjustment of the start-stop times, by
The . 008" in steps (3, 4) should be checked
(Check that the non-driving moving pulley does
Do this by inserting a . 005" feeler gage between the
Adjustments
The moving pulley on the left (facing the machine)
If the moving pulley rotates, it is likely that it is
The pulley sometimes rotates because of its inertia,
To verify this possibility, remove the
If there is still the same amount of
The signal envelope should rise to a
However, if the moving pulley on the
58
No drag should be felt.
The moving
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