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E L E C T R I C A L
P R I N C I P L E S
49
Sign control checking is accomplished by com-
paring X-punchings in the multiplier and multi-
plicand fields against X's in the product field. If
the factors indicate a negative product and the
product is not so identified (or vice versa), the ma-
chine will stop and indicate an error.
The only additional control panel wiring nec-
essary for a checking operation is the wiring of the
card column con,taining the product X to the
PR
x
CHK
hub from the first set of brushes. The X's
for the multiplier or multiplicand are sensed
through the
MPX
or
MCX
hubs.
However, when
checking, the factor reversal switch is
ON
and R25
is picked up; consequently the
MPX
and
MCX
hubs are reversed so that a mul'tiplier X picks R95
and
a
inultiplicand X picks R96.
In order to set up a given problem, assume an
X punch in the multiplicand field only. The single
X means that the product is negative and that an
X should be punched. If for some reason rhe pro-
duct X is not punched, the machine must detect
this
2s
an error.
The sequence of events involved in a sign check
.Ire shown on the chart in Figure 5 1B. Note that
when an error is sensed, the machine is not stopped
until the end of the cycle during which the card
in
error passes the second set of brushes.
The circuits are completed in the sequence in
which they are traced below. Remember that R25
is energized during a check run and rhat RlOO
picks up at X time of each cycle under control of
P3 7.
When the card passes the first set of brushes,
the multiplicand X is read and R96 picks as fol-
lows: post 3, through fuse 8, R96P coil, R l OOAL,
R25BL
N/O
MCX
hub, control wire to hub of
read for entry and control brushes, individual
brush, X hole, contact roll, common brush, R8B,
CB's, to post 1. R99 would be energized if the pro-
duct X were punched.
Since the assumption is
that no product X is punched, R99 is not picked
up.
R96 holds through its R96H coil, R96AU
points, and P39 until 5 of the nexr cycle. R96B
points set up the circuit to R97P, which picks as
follows when P40 makes: post 3, through fuse 8,
R97P coil, R96B
N/O,
R95B
N/C,
R99B N/C, P40,
to post 1. R97 holds through its R97H coil, R97A7
and P41 until 11.5 of the same cycle. R97B sets
up a circuit to R98P, so that at X time of this
cycle, R98 is energized as follows: post 3, through
fuse 8, R98P coil, R25AL
N/O,
R97B, R100BU7
through CB's, to post 1. R98 holds through its
R98H coil, R98AL, and P39; R98AU points set
up a circuit to R l OlP so that RlOl picks when
P40 makes. RlOl then holds until 11.5 through its
R l O l H coil, RlOlA, and P41. RlOlB points set up
a circuit to energize the error relay at X time as
follows: post 3, through fuse 7, R57P coil, R31B7
to R3 8A
N/O,
through RlO lB (Section 14B), R -
100BU, CB's to post 1.
When R57 picks, its R57B points open, causing
the machine to stop as previously explained. Also,
the error light will glow to indicate an error.
Observe tha,t if the X to identify a negative
product had been punched, R99 would have picked
and held through its R99H coil, R99A, and P39;
then when P40 made, R99B would be transferred
along with R96AL, and R97 could not pick up. If
R97 does not pick up, nothing further happens in
the checking opera,tion. The R99B points in com-
bination with the R95 and R96 points provide a
means of completing a circuit to R97 for proper
X punch and X-check control.
Since it is recommended that X's be punched
over the units column of a field, it is necessary ro
suppress the X check when using the double punch
check.
This may be done by wiring the units
column through the column split, so that only the
0-9 positions of the card column are checked for
double punch.
Class Selectors (Optional)
Class selectors are optional features on this ma-
chine.
If one class selector is, installed, relays SO
through 86 are used.
The second class selector
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