Play Meter

By Zac Oliver
Timed sequences
on control circuits
The understanding of timed se -
quences on control circuits are
essential when troubleshooting pin -
ball games . All manufacturers supply
motor switch charts in their schema -
tics . Some are detailed , so me are
not. Comparativelv. Williams , Gott-
lieb , Stern (formerly Chicago Coin) ,
and Bally use similar circuitry . For
e xample , when a coil is energized to
latch some mechanism or switch s , a
holding circuit is provided to keep the
mentioned coil energized during a
timed period by means of a switch
actuated through a motor cam
(Figures la ,b ,c ,d,e) .
Pulses are fed to other coils ,
holding the control switch the
number of pulses selected and then
releasing the control switch , elimi-
nating the other pulses (see Figures
la ,b,c ,d) .
Gottlieb's schematic provides a
good. easy to understand sequence
chart for the motor switches and their
position related to each other . The
only information needed is to know if
th e switch in focus is " made " or open
when the motor cams are at their
home position . The stacks of switch-
es at positions 1, 2 , 3 , and 4 (see
Figure 4) , are distributed in five
levels : A , B, C , D, and E, from the
bottom up (see Figure 5) . Take for
exa mple Motor lA switch . i.e . switch
located at position /I 1, level A. In the
Motor Sequence Chart , (Figure 3) ,
Motor lA switches are shown pulsing
five times during a one -third revolu-
tion of the motor cams (120 degrees)
(Bally and Williams will turn 180
degrees) .
The normally opened switches at
position lA will be closed at the peak
of each tooth placed around the
bottom cam . The opposite will
happen to a normally closed switch .
A normally closed switch at 2C
(see Figure 3) will open during the
second pulse of lA . A normally
opened switch at 3B will close (or
open) at the third pulse of lA o
The switches located at position
/1 4 , stack on level A will pulse
between the pulses of lA (Bally and
Williams use the same system
PLAY METER , March , 1979
offsetting th e switches on a second
impulse cam usually for reset pur-
poses on their four players) . The
switch stacks arrangement and actua -
tors (switch dogs) displacement
around the control motor will feature
an inhibition system if several
switches are used in series .
It is a different approach from the
other manufacturers where a relay ,
timed , through its switches will pulse
a unit (e .g . credit unit) to change the
number of pulses , just change the
holding time . Th e credit unit on a
Williams game will register the proper
amount of credits depending o n how
long the 25-cents relay (in this case)
stays energized (see Figures la ,b,c,
d) . Gottlieb maintains the second
chute relay (W) held through its
longest " hold in " circuit and selects
the pulses through the second coin
adjustment (see Figures 2a ,b) .
If fo ur plays for a coin is selected,
the GR -BLK (green and black
mottled wire) will be placed at
position 4 in the third chute
adjustment terminal. Motor lA , will
supply five pulses directly to Motor
2C switch , since Motor 4C and 4B
are bypassed by the chute adjust-
ment connector. Looking at the chart
we see that only one pulse (the
second out of five) will be disabled ;
Motor 2C will open at the same time
the second pulse from Motor lA is
made (see Figures 2a ,b , and 3) .
If one selects two plays for a
quarter , Motor 2C , Motor 4C , and
4B will be in series with Motor lA
Figure lA
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Figure IB
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