IBM Selectric Reference 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 plus five and o .. e'·
half rotate is encountered, the following adjust-
ment procedures, whi ch are not the norma I speci-
fications, may be used:
A. The rotate spring tension may be increased
to 34 ounces (Mod. 1062 on Iy). All other
printers should favor high side of normal
spec. (32 ounces) .
B. The ski rt clearance shou Id be adj usted so as
to favor the low side of the spec. (.023")
C. The typehead homing may be readjusted so
as
to increase the negative or clockwise di-
rection of the typehead as the detent enters.
Example: With the machine half-cycled to
a pi us five character, and all clockwise play
taken out of the head, the detent shou Id en-
ter approximately .022" from the center of
the notch. This will effecHvely 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 paw I, it wi II tend to rotate back-
ward, closing the spring clutch and causing
it to drive prematurely. If, at the same
time, the cycle clutch is activated, an in-
creased momentum wi II be felt throughout
the cycle shaft system, reSlulting in the type-
head over-rotating.
E. The motor belt must also be kept within its
specifications for tightness,.
F. The se lector latch to bai I clearance shou Id
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 wi II be most pre-
dominant on machines operating in an open-end-
ed mode, i . e ., pri nters whi ch do not use C 1 and
C2 to gate incoming pu Ises. The over-rotating
condition is being actively investigated by Engi-
5-17
neering, and any more improvements or refine-
ments of adjustments wi II be released to the Field
as soon as
they are avai lab Ie.
EXTRA CYCLES
(MECHANICAL
KEYBOARD ONLY)
11 .0 Extra Cyc les
Extra
cyc les may be defi ned as an unwanted +5 rotate,
3 ti It character selection (usually a period). The
most common
causes of Extra Cyc les are listed be low
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 paw I 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 restori'ng overthrow, the nylon
cam should
be replaced. The nylon cams are now be-
i ng g round to c loser to lerances .
11 .3 Insufficient or excessive latch bite or a worn latch
wi II cause extra cycles. 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 Fiicking
Flicking'is an erroneous character induced 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 bai I
down, but does not latch an interposer. The Cycle
Clutch Pawl wi II 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 .00111 - .002" as it is unlatched by on in-
terposer. This adjustment moy 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