Contact Ratings; Instructions For Use; Paper Tape Standards And Channel Identification; Threading Tape - Tally 424 Manual

Drive
Pulse
r-i
.....
0
0
H
t
(a)
3. 7 Contact Ratings
Drive
Escapement
Puls~
Cs
Coil 70
ohm or
Rs
320
ohm
{b)
{ c)
Figure 10. Spark Suppression Waveforms:
(a) Coil current without suppression
(b) Suppression Circuit
(c) Coil current with suppression
12
mo
In normal usage, the same pulse that advances the tape is used to interrogate the con-
tacts. As shown on the timing diagram, Figure 8, contact make or break always occurs after the
expiration of the drive-interrogate pulse. Consequently, the contacts are rated for a pulse-
carrying capacity of 2 amperes, 48 volts DC.
In applications requiring the contacts to make or break a live circuit, a current of more
than 5 milliamps will begin to deteriorate contact life . However, contacts are replaceable.
4.0 INSTRUCTIONS FOR USE
4.1 Paper Tape Standards and Channel Identification
The Model 424 Reader is designed to read any perforated tape that conforms to industry
standards . For standard dimensions and channel designations, refer to Figure 11.
4 .2 Threading Tape
To thread a tape through the read head, raise the lift lever handle (24, Figure 13). This
raises the read head so the capstan is clear. Lay the tape across the capstan so that the pins
project through the sprocket holes. Be sure the tape is positioned so that the pins do not project
through the holes of
a
data channel. Also
be
certain that the tape is threaded with channel 5
nearest the operator . While holding the tape in position on the capstan, push the lift lever down
until the lever locks in a slightly over center position. The tape is now properly threaded, and
the reader is ready for use.
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