IBM Selectric Service Manual

Flattened Notch
Figure 10.2
2. SELECTRIC I/O Printer CEM #9 announced an
improved typehead ball joint which tightened up
the specification on typehead play. This new
"ball joint with .045" head play wi II also help to
alleviate the possibility of the type head over-
rotating.
3. If an excessively bad case of p Ius five and one-
half rotate is encountered, the following adjust-
ment procedures, which are not the normal speci-
fications, may be used:
A. The rotate spri ng tensi on may be increased
to 34 ounces (Mod. 1062 on Iy). All other
printers should favor high side of normal
spec. (32 ounces) .
B. The skirt clearance should be adjusted sa as
to favor the low si de of the spec. (.023")
C. The typehead homing may be readjusted so
as
to increase the positive or clockwise di-
rection of the typehead as the detent enters.
Example: With the machine half-cycled to
a p Ius five character, and a II clockwise play
taken out of the head, the detent shou Id en-
ter approximately .022" from the center of
the notch. This will effectively split the
homing so that the detent will enter .002"
to the left and right side of the notch.
D. The condition called out ·in 15.10 may also
result in plus five and one-half rotate. If
the cyc Ie shaft does not detent properly on
its
check pawl, it wi II tend to rotate back-
ward, closing the spring clutch and causing
it to drive premature Iy. If, at the same
time, the cycle clutch is activated, an in-
creased momentum will be felt throughout
the cycle shaft system, resulting in the type-
head over-rotating.
E. The motor belt must also be kept within its
specifications for tightness.
F. The selector latch to bail clearance should
be held to a minimum in order to prevent the
bai I from giving too much shock to the sys-
tem as it is driven down.
This over-rotating condition will be most pre-
dominant on machines operating in an open-end-
ed mode, i.e., printers which do not use Cl and
C2 to gate incoming pulses. The over-rotating
condition is being actively investigated by Engi-
4-17
neeri ng, and any more improvements or refi ne-
ments of adjustments will be released to the Field
as soon
as they are avai lab Ie.
EXTRA CYCLES
(MECHANICAL
KEYBOARD ONLY)
11.0 Extra Cycles
Extra cyc les may be defi ned as an unwanted +5 rotate,
3 tilt character selection (usually a period). The
most common
causes of Extra Cycles are listed below
in order of probabi lity.
11.1 CYCLE CLUTCH LATCH LINK PAWL BITE
The pawl must overlap its keeper by 1/2 the thickness
of the keeper. (Adjust the bai I upstop).
11.2 CYCLE CLUTCH LATCH RESTORING
Adjust so that the pawl overthrows the keeper by
.025" - .030". Caution - Excessive overthrow will
a
Iso cause extra cyc les because the pawl wi II bounce
off the keeper.
NOTE: The nylon cam may not provide equal re-
storing motion on both lobes. Adjust the overthrow
to meet the specifications on the lobe which provides
the least motion. If the two lobes cause more than
.020" difference in restoring overthrow, the nylon
cam shou Id be replaced. The nylon cams are now be-
ing ground to closer tolerances.
11.3 Insufficient or excessive latch bite or a worn latch
wi II cause extra cyc les. Adjust the entire keeper
bracket assembly (front to rear) to obtain .030"-.035"
latch bite on the sleeve. This is equal to the thick-
ness of the latch. Caution - If this adjustment is
changed readjust per Section 11.2.
11.4 BINDS IN THE CYCLE BAIL
The bai I must be free to rotate about its axis on both
the right and the left side. If a bind is suspected,
remove the bai I and polish the ends with crocus cloth.
FLICKING
MECHANICAL
KEYBOARD ONLY
12.0 Flicking
Flicking is
an erroneous character inducea by the
operator. It is usually a +5 rotate, 3 tilt 'selection
(period for most systems) and is caused by the oper-
ator tapping a keybutton which drives the cycle bail
down, but does not latch an interposer. The Cyc Ie
Clutch Pawl will release and cause a +5 rotate, 3
ti
It se lecti on .
12.1 ADJUSTMENTS
TO MINIMIZE FLICKING
The cycle clutch latch link pawl should clear its
keeper by .001" - .002" as it is unlatched by an in-
terposer. This adjustment may be observed through

IBM Selectric Specifications

General

Type	Electric typewriter
Introduced	1961
Keyboard Layout	QWERTY
Carriage Return	Electric
Manufacturer	IBM
Printing Technology	Typeball (golf ball)
Power Source	AC Power
Power Supply	120V AC