IBM 29 Card Punch Field Engineering Maintenance Manual page 69

contacts should have a minimum of 0.010-inch air gap
whenrestoring magnetsare energized.
Note: It is important that restoring bail contacts open
before the latch or bail contacts.
4.12.1.4 Keystem Contacts
Strap Contacts: The NO contacts should have a 1/32-inch
minimum air gap. The NC contacts must open with the
minimum pressure of 15 grams at the end of the strap and
with minimum movement (1/64 inch) of stationary strap
when contacts open.
1. When the MP keyis pressed 3/32 inch + 1/64 inch, the
upper contact must break. Further depression of 1/32
inch causes the lower contact to make.
2. When the ALPHA and DUP keysare pressed 3/32 inch
+ 1/32 inch, their contacts must close. If the operator's
palm strikes the ALPHA key, increase the contact air
gap.
3. When the NUMERIC key is pressed 3/32 inch + 1/64
inch, the numeric contact must open.
Microswitch Contacts: Position single microswitches to
transfer 0.015 to 0.060 inch prior to the downward limit of
keystem travel. Position double microswitches to transfer
the outboard switch 0.015 to 0.060 inch prior to the
downward limit of keystem travel, and the inboard switch
to transfer 0.010 to 0.045 inch prior to the outboard
switch.
Figure 4-54, Keyboard Permutation Unit — Rear
4-38 (4/69)
4.12.1.5 Contact Bails
Whena new bail (Figure 4-54): is installed, form all tabs on
each bail for 0.000-inch to 0.005-inch clearance to associ-
ated operation ears on permutation bar, with latch assem-
blies in restored position. This may be checked on a
keyboard with its covers removed. Check tension required
to just open a closed bail contact for each key that operates
that bail; tension should be at least 15 grams. Bail contact
air gap and tension on operating strap affects this tension
and should be checked before a measurementis attempted.
4.12.2 Hook Support Bar Adjustment
Bar must be parallel with interlock guide bar, directly
beneath it, along their longest edges, within 0.008 inch.
This is to prevent binding of the latch.
4.12.3 Permutation Bar Adjustment
Adjust the four setscrews that position the latch stop plate
to allow bars to drop 0.042 to 0.048 inch. Measure a bar
near each holding screw. To measure, lay a 6-inch rule
across the top of the permutation bars. If the bar whose
travel is to be measured is lower than the 6-inch rule,
measure this amount and addit to the 0.042 to 0.048 inch
given previously. Trip the latch and measure the distance
that the top of this bar is below the edge oftherule.
4.12.4 Restoring Magnet Adjustment
1. With all latch assemblies restored, insert 0.003-inch gage
between armature and magnet core and hold them
sealed. Position magnet brackets evenly until restoring