Coin Slot Magazine - #087 - 1982 - May[International Arcade Museum]
his month we will discuss the third and
device operating the switch (e.g. score motor 'cam
final type of component which makes up
follower,' playfield 'rollover wire,' etc.). Attached to the
the basic electrical circuit, the 'switch'
(often referred to as'contacts' or'points').
'spacer1 which pushes against the next actuator blade
The switch provides the control of the
operation of the circuit by turning on and off the flow of
electric current from the 'power source' to the 'load.'
Switch malfunctions probably account for 80 to 90
percent of the electrical problems occuring in games.
opposite side of this first actuator is a round fiber
in the stack causing it to move as well. Two or more
switches can thus be stacked in this mannersuch that
moving the first actuator blade will move all others in
the 'stack' thus 'operating' all switches in that stack.
Each switch has two positions or'states.'The'normal
Most of these troubles are caused by dirty or misadjusted
state' is when the device actuating the switch (relay,
switch contacts. Correction of these types of problems
cam follower, playfield bumper, etc.) is in its'normal' or
'at rest' condition. The 'operated state' is when the
will be discussed on next month's issue.
Early electric games contained a small number of
switches (some had only one) but as the complexity of
electrical circuits in games increased the number of
actuating device has been activated (e.g. relay ener
gized, cam follower moved by a cam, bumper struck by
a ball in play, etc.). It is important to understand these
idly. Games of the sixties and
seventies contained well over
states when working with switch
circuits as most of the terminolo
gy involved with switching circuits
100 sets of switch contacts each
is connected with these concepts.
of which was capable of causing
a problem.
Basically a switch consists of
SWITCH CONFIGURATIONS
The two most common switch
configurations each involve two
contacting blades and are refer
switches began to increase rap-
two pieces of metal, each with an
electric wire attached to it. When
these two pieces are touched
together an electric current can
flow between them, completing
=
=
PINBALL
TROUBLE
SHOOTING
red to as 'normally closed' and
'normally open.' Referring to
Figure 2A, the uppermost switch
(of the three switch 'stack' shown)
two wires are attached. The
switches used in gamesgeneral-
ly consist of metal strips (called
isa'normallyclosed' switch.The
relay is shown in its unenergized
state, therefore its associated
switches are in their'normal state.'
'blades') withasolderterminalat
The upper switch can be seen to
the electrical circuit to which the
one end (for connection of exter
nal circuit wiring) and small metal
'contacts' (often
refered to as
'points') embedded in the blade
near the other end. Two of these
blades
generally
make
up
a
PART 5
SWITCHES
exceptions which
will
be
dis
the terminal end by insulating
'spacers' (usually made of bake-
lite). Two or more of these switch
es may be mounted together,
ing by placing small dots to the
left of all switches which are
between them. This type of switch
is called 'normally closed' be-
======
a relay) is shown in Figure 2A.
One of the blades of each switch is slightly longer
than its 'mate' and is the one which is 'actuated'
(moved) to cause the switch to operate. In most relay
applications(and sometimes on score motors) the tips
.com
m
:
u
from -muse
d
e
e actuator is moved
When the relay o is
ad energized
ad this
l
c
r
n
a
causing the
to move with it (thus
Dow actuator
ww. blades
w
/
operating their
respective
switches). This is illustrated
/
:
tp (relay unenergized) and 2B (relay ener
ht 2A
in Figures
of these actuator blades protrude through slots in a
non-metalic'actuator1 attached to the relay armature.
gized).
In other switch applications involving a 'stack' of
switches, one of the actuator blades is moved by the
44 — THE COIN SLOT
This I have illustrated in the draw
ated (as shown in Figure 2B) the
switch is in its 'operated state'
By Russ Jensen
and the upper contacts are'open'
=========== and thus no current can flow
using additional spacers between them, to form a
'switch stack' An example of such a 'stack' (as used on
© The International Arcade Museum
current to flow between them.)
closed. When the relay is actu
'switch' although there are some
cussed shortly. The blades are
separated from each other, at
be 'closed' because its two con
tact points are touching (allowing
= cause its contacts are 'closed'
(touching each other) when the switch is in its'normal
state.'
Just the opposite is true of the middle set of contacts
shown in Figures 2A and 2B. They are 'normally open'
since, as can easily be seen, they are 'open' when the
switch is in its 'normal state' (relay unenergized) and
'closed' when it is in the 'operated state' (relay ener
gized). Thus for this type of switch, current can only
flow when the switch is operated as opposed to the
'normally closed' switch where current flows when the
switch is not operated.
The other common switch configuration used in
games involves three switch blades and is referred to
as a 'Single-Pole-Double-Throw1 switch. This is most
often abbreviated as 'SPDT and often also called a
'Form C switch. Incidentally, 'normally open' switches
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May, 1982