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Figure 1-11. Test Probe
be performed to determine the timing of circuit breakers.
The voltmeter can also be used while the machine is
operating, to detect the presence and relative magnitude of
the voltage.
1.6.5 Cycling Manually
Turn the motor switch off. Observe machine functions
while manually operating the escapement gear train and the
punch clutch. This allows voltages to be checked at any
time during the machinecycle.
1.6.6 Interchanging Units
Keyboards, relay boards, or relay gates may be inter-
changed with other machines of the same type and feature
configuration. This can help isolate suspected units when
diagnosing intermittent troubles.
1.6.6.1 Relay Gate
The relay gate in either type of machine is easily remove-
able. In the reed-relay machine, drop the relay gate out of
the guide tracks through the slots provided. In the
wire-contact relay machine, first slide one tab out of the
slot, then slide the other tab out.
1.6.6.2 Arc Suppression
Arc suppression is necessary for the proper operation and
longevity of the reed-relay switches. If trouble is suspected
in an arc suppression network, it must be substituted with
another.
CAUTION
Removal of arc suppression for diagnosis can cause
considerable damage as well as faulty operation.
1-10
(4/69)
1.6.6.3 Reed Relays
When inserting reed relays on the circuit board, care must
be exercised not to exert pressure on the coil portion of the
relay. Pressure exerted on the coil can cause therelay to
flex, and breakage of the glass reed switch may occur. To
prevent this breakage, the relay must be positioned and
pressed on the card with equal pressure exerted on each of
the plastic ends of the relay (Figure 1-12).
A short caused by a defective part or a slip of the hand
while troubleshooting could damage several relays. All
relays in the circuit between the short and the line should
be checked because the sudden surge of current could cause
the interceding relay points to weld or develop a tacking
condition. Do not remove or replace relays during a
machinecycle.
If tacking is suspected, do not jar the machine because
the tacking problem may disappear temporarily. Do not
interchange relays or relay types. If the relay used does not
have a hold coil, do not put one that has a hold coil inits
place. Do not interchange relay reeds, The individual relay
reeds are matched and should not be interchanged by
disassembly or use of ones from otherrelays.
Repeated relay insertions and removals can cause the glass
envelope to break; Berg connectors maylose tension and
cause intermittent failures. Check connector alignment with
a 0.010-inch feeler gage, aligning it with adjacent con-
nector.
Figure 1-12. Reed Relay Insertion
1.7 DIFFICULT-TO-ANALYZE AND INTERMITTENT
FAILURES
There are some sources of trouble in the 29 Card Punch
that cause varying results and are difficult to diagnose.
Amongtheseare:
1. Friction drive torque (too much,toolittle, or jumpy)
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