IBM Selectric Manual page 28

CAUTION: Excessivelyadvancedor retarded tim-
ing can cause parts damage as well as poor hori-
zonta

al ignment or improper selection. This could
happen if the detent entered the wrong notch or re-
mained in the notch too long.
NOTE: Be sure to maintain
.002"
to
.004"
end
play in the print shaft.
14.
Shift Motion - The shift arm adjusting screw (Fig.
69)
should be adjusted in or out to obtain
180 0
rotation of
the typehead during a shift operation.
The adjustment can be checked by observing the detent-
ing in the lower case compared to the upper case using
the letter "M". The detent MUST enter the lower case
notch EXACTLY the same as it does the upper case notch.
Check by half-cycling the machine and manually with-
drawing the detent. Remove the head play clockwise
and allow the detent to re-enter slowly. A final check
can be made by comparing the detent withdrawal timing
oftheupperand lowercase. They must be exactly alike.
Maladjustment can cause misalignment in the lower case
while the upper case remains good.
CAUTION: Be sure that the shift cam is detented at
each position during the check and that the cycle shaft
is
p~operly
latched at the half-cycle position.
Shift Arm
Adjusting Screw
FIGURE
69.
Shift Motion Adjustment
15. Final Check - After completing the foregoing ad just-
ments, a final check should be made to see if any re-
finements are necessary. Compare the coarse a I ignment
detenting for the letters WORMT. The band width of
this group should not exceed.
030"
and none of the group
should detent closerthan
.010"
tothe center of the notch
when the head play is removed in
th~9Qtiv_e
direction.
The following table can be used to diagnose the cause of
excessive band width between the letters WORMT. These
letters are chosen because of their rotate selections. If
anexcessivebandwidthexists, it will be greatest among
these characters. In making the diagnose, follow the
sequence as listed.
26
Excessive Band
Width Between
T (zero) and 0 (-1)
R (-3) and W (+5)
R, W, and T
M (-5) and R ( -3)
Cause
Incorrect balance
Incorrect rotate arm motion
Incorrect latch clearances
Incorrect paddle adjustment
Unwanted compensator roller droppage may result from
one or more of the foi iowing.
a. "Beqting the shift"
b. Improper detent timing
c. Malse lection (popping latches)
d. Incorrect rotate spring tension or damper spring ten-
sion.
e. Binds in the typehead, upper ball socket, rotate
shaft, rotate pulley, or rotate spring.
f. Binds in the compensator or lever system.
g. Loose differential mounting bracket.
h.
Ex~essive
band width or head play.
If
the band width appears to be all right but the align-
ment is not satisfactory, check the· following items:
a. Detent timing.
b. Playorbindsinthe tilt or rotate detents. Side play
in the rotate detent can be checked by holding down
the interposer for the letter" N" so that it repeats
for a full line. Move the carrier back manually
and repeat the operation without indexing. The
second line should cover the first line exactly. If
any of the characters are shadowed, side play in
the rotate detent cou Id be the cause.
c. Loose fitting upper ball socket.
d. Excessive play in the carrier or rocker.
e. Binds in the rocker parts.
f.
I f the -5 characters vary horizontally, improper
damper spring tension could be the cause.
g. Improper tilt adjustments can cause poor horizontal
alignment by delaying the detent seating.
NOT E: A fte r the mac h i ne has been in use for some
time, wear in the tape system will allow the typehead
to drift in the negative direction. It is not necessary to
sl ip the rotate shaft within the rotate pulley to REFINE
the typehead position. The proper position may be gain-
ed by refining the eccentric stud adjustment. Be sure to
RESEAT the compensator roller after changing the eccen-
tric stud ad justment. (Maintain the roller position 1/16
11
from the topofthe slot by adjustment of the rotate link.)