IBM Selectric Maintenance Manual page 46

+5 +4 +3 +2 +1 0 -1 -2 -3 -, -5
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Affected By
FIGURE 78. Insufficient Rotate Arm Motion
Ratio Change
detent well within the acceptable band width provided
that all of the previous adjustments have been made cor-
rectly. If a slight difference in detenting must exist be-
tween the -3 and +5 characters it is permissible and some-
times desirable provided that the -3 detents more nega-
tive then the +5 character. In other words, it is better
to have too much rotate arm motion than too little. The
reason for this is to place a small amount of wear poten-
tial into the system for the areas of the differential mech-
anism where wear cannot be compensated for (positive
latches and latch bail). Thus, as wear occurs in these
areas causing the rotate arm motion to decrease, the de-
tenti ng variati on between the +5 and -3 characters will
also reduce.
Figure 78 lIustrates the effects on detenting caused by
insufficient rotate arm motion. Notice that the largest
detenting variation occurs between the +5 and -3. This
is because the +5 and -3 operate in opposite directions
and the error that appears when these two positions are
compared is the combined error of both positive and neg-
ative motion.
If the rotate arm motion was excessive the detenting pat-
tern would remain the same except that each detent
would be on the opposite side of its detent notch.
NOTE: The adjustment may be left loose during each
check until the correct position is obtained.
11. Final Typehead Homing - (Eccentric Stud Adjustment)
Use the following procedure to adjust the eccentric stud.
FIGURE 79. Damper, Spring Stop - Preliminary
, Adjustment
2-23
a. Damper spring stop - as a preliminary adjustment,
slide the damper spring stop down as low as it will
go behind the damper spring (Fig. 79).
b. Raise the compensator roller all the way to the top
of the V-shaped wedging slot.
c. Half-cycle an upper case -5 character and adjust
the eccentric stud (Fig. 80) in against the machine
si deframe unti I the -5 character detents .010" to
.020" in the negative direction from the center of
the detenf notch when the head play is lightly re-
moved in the negative di recti on (Fig. 81). Make
sure that the damper spring is fully collapsed against
the machine si deframe.
After the eccentric stud has been properly adjusted
the compensator roller must be reseated by raising
it to the top of the V-shaped slot and striking a ser-
ies of -5 characters. The compensator roller should
seat 1/16" down from the top of the slot. If it drops
too little or too much the rotate link should be ad-
Eccentric Stud
(Make Adjustment Here)
FIGURE 80. Eccentric Stud