IBM 727, Руководство по инструкции

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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). The start-stop times must be checked
in both directions with the scope. A minor adjustment of the start-stop tim es, by
changing the position of the stop capstans in the proper direction, is the proper p ro­
cedure to obtain optimum operation. The . 008" in steps (3, 4) should be checked
after any change in the stop capstan setting and should not be changed m ore than
. 003" to obtain the proper timings. (Check that the non-driving moving pulley does
not strike the drive capstans. Do this by inserting a . 005" feeler gage between the
moving pulley and the drive capstans on the non-driving side. No drag should be felt.
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, Forw ard-Reverse Magnet, and Stop-Capstan
Adjustments
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. The moving pulley on the left (facing the machine)
should not rotate appreciably. If the moving pulley rotates, it is likely that it is
striking the drive capstan. The pulley sometimes rotates because of its inertia,
without having interfered with the capstan. To verify this possibility, remove the
capstan motor plug and repeat the above test. If there is still the same amount of
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 tim es. The moving
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-w rite head in that channel. The signal envelope should rise to a
fairly steady value if conditions are normal. However, if the moving pulley on the
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 unitTs being selected, or by using the tape drive tester.
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