IBM 727, Руководство по инструкции

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3. The " start envelope" should be sim ilar to Figure 24. After calibrating the
scope sweep circuit, use a positive external trigger input from 03J-P2. Obtain an
input signal of 20 volts (peak to peak) from Fn. See section 1 9 .4 .2 . Variations from
this envelope can be caused by gap adjustments, the m oving-coil wave form , or mov­
ing pulley interference, as shown in Figure 24.
4. The "stop envelope" should be sim ilar to Figure 25. Use a negative external
trigger input from 03J-P2. Obtain an input signal of 20 volts (peak to peak) from Fn.
Variations from this envelope can be caused by gap adjustments, the m oving-coil
wave form or moving pulley. See section 1 9 .4 .2 .
15.8. 7 R everse Magnet Transfer
Forward to Backward Status. With the tape unit not selected and in stop status,
use a positive trigger input from 02J-P1. Obtain an input signal with probe on 02J-P6.
The magnet may be transferred from the backward to the forward status by using the
switch provided on the customer engineer control box or by using the tape drive tester.
The m agnet-coil voltage wave form then should compare with Figure 26. Variations
from this wave can be caused by improper gap adjustments, seating of armature, or
coil current, as shown in Figure 24. See section 1 9 .4 .4 .
Backward to Forward Status. This status is the same as above except that the
positive trigger input is from 01J-P1 and the input signal is obtained with probe on
01J-P6. See section 1 9 .4 .4 .
1 5 .8 .8 Moving-Coil Wave Form
The tape unit need not be selected fo r this check. The m oving-coil wave form
should compare with Figure 27, when the scope is connected across the 10-ohm r e ­
sistor at connectors l r and 2n using internal sync, five ms per m ajor division, and
.5v per major scale division sensitivity. CAUTION: HIGH VOLTAGE. The scope
fram e is about 100 volts above ground with the above connections.
Change the polarity on internal sync to get a stop pulse and a start pulse both of
which are the same as in Figure 27. See section 1 9 .4 .5 .
1 5 .8 .9 Systems Checking the Inter-Record Space
With mechanical adjustments, start and stop envelopes and tim es, and start de­
lay in the control unit properly adjusted; with the tape unit selected, check the inter­
record time with scope by reading records written on same machine. Obtain signal
input from a read bus using external sync from an appropriate e n d -of-record pulse.
The time between record s should be 10 ms (+2 m s, -0 m s). The in ter-record space
measured on this tape when developed should be 3 /4 " + 1 /1 6 ". The effect of start
and stop time on in ter-record space is shown in Figures 24 and 25.
15.9 MISCELLANEOUS ADJUSTMENTS
1 5 .9 .1 Machine Reel Sensing Arm
Adjust contact operating screw so that points make contact when about 1 /2 " of
tape is on the reel.
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