IBM 29 CARD PUNCH Maintenance Manual page 54

S225-3357-3
FES: SS234069
5. Loosen acoustic isolators or mounting screws.
6. Remove the lower stacker card guide.
7. Position the stacker plate parallel to and with 0.003-inch
I
to 0.007-inch clearance between the bottom of the card
and the lower stacker rail (use the support bumpers to
the rear and below the stacker when stacker support
bracket is on the machine).
8. Tighten the isolators and replace the card guide.
9. Adjust the traveling card guide bumpers t o allow
0.005-inch to 0.01 0-inch clearance between the traveling
card guide and the card when the feed clutch is latched
and a minimum of 0.00 1-inch clearance when the card is
stacking. When properly adjusted, the operating noise is
reduced by the rubber bumpers.
4.10 PROGRAM DRUM UNIT
4.10.1 Sensing Assembly Service Check
4.10.1.1 Card Life
The program card should be changed daily when usage is
heavy. The sensing wheels, in correct adjustment, should
graze the surface of the program card. Improper tension on
the program sensing arms shortens life of the program card.
Worn program cards may cause elusive failures.
4.10.1.2 Drum Interchangeability
Determine interchangeability by checking all drums against
a master drum. Replace worn gripper cam shafts.
4.10.1.3 Drum Eccentricity
1. Mount a program card with 4's punched at about
15-column intervals.
2. Space to the columns preceding the punched ones and
observe the distance from the starwheel to the hole.
Variation in the starwheel-to-hole distance is an indica-
tion of drum eccentricity and should not exceed 0.003
inch.
4.10.1.4 Sensing Wheels
Wheels must pivot freely. Check for oxide deposit on
pivots, and for proper lubrication. Sensing arm lever must
move freely on its pivot shaft.
4.10.1.5 Sensing Contacts
Contacts should seldom require adjustment. When trouble
is suspected in this area, remember that there are several
possible sources of trouble inside and outside the sensing
unit that may make this adjustment erratic and unstable.
Check the following points before adjusting the sensing
contacts; it may save a callback.
1. Inspect straps and contact screw heads for pits and
nodes.
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2. Make certain that program drum shaft adjustable yoke is
not loose.
3. Check for wear between end of shaft in program drum
and hole in column indicator wheel that locates and
seats drum.
4. Check for excessive play in the escapement gear train,
while power is off.
5. Test friction drive torque.
6 . Be sure that the plastic safety cover is installed over the
terminals.
Service time on these contacts is greatly reduced if the
method outlined in 4.10.2 is closely followed.
4.10.2 Sensing Assembly Adjustments
With the escapement armature stopping the escapement
ratchet tooth and machine power on, a zero reference point
is established at any single column of the program unit by
using the timing tool, part 453160 (Figure 4-35). The use
of millisecond (ms) notation instead of 1/12 of an
escapement tooth is to aid in determining relationships of
the program unit timing t o the escapement during a skip
.-
.
operation and does not imply using an oscilloscope.
Perform operations in the order shown:
1. Set the starwheel tension when the contacts are changed.
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2. Set the starwheel duration.
3. Use only a starwheel with the correct duration to set the
forked armlstarwheel timing.
or the cover screw
Figure 4-35. Timing Tool