September 1 997
STAR*TECH JOURNAL
THE IMPORTANCE OF PROPER GROUNDING
(TALES FROM THE ARCADE)
TEAM SEGA PINBALL
Joe Blackwell, Eric Winston, Doug Lemons,Jay Alfer
Sega Pinball, Melrose Park, Illinois
Yes! We all know that the "third
prong" on your A. C. line cord is
important for safety reasons or
should we say very important for
safety reasons as in all external
metal parts on a pinball are
grounded for this reason.
Did you also know that it is im-
portant from the
standpoint of reduc-
ing noise in the sys-
Would you
plug your
tem?!
would happen during Attract
Mode and Game Mode. Over
the phone we could not localize
the problem through conven-
tional harness tugging, board tap-
ping, board swapping or line volt-
age tap changes. We finally had
one of our techs drop by since it
was in the Chicago area. He
Pinball Game
There is an extreme
amount of electrical
noise generated in a
pinball machine
which to be properly
suppressed
or
shunted must have
somewhere to go
such
as
Earth
Ground. When there
is no proper ground
connection then
havoc can be created
within the workings
of the microproces-
sor circuit.
into this?!
Actual Case:
A customer com-
plained of a new Space Jam Pin-
ball intermittently resetting. It
spent a fair amount of time uti-
lizing the systematic approach
ruling out all of the basics, every-
thing appeared OK. He finally
took a look at how the game was
plugged into the outlet. What he
found was a multi-outlet strip
with 5 games plugged into it with
no third prong grounding pin on
the plug for the strip.
Imagine the amount of
noise being induced into
the line input of each of
these games.
When our technician had
the location replace the
strip with one that was
properly grounded, the
problem went away.
Remember " ... a short cut
is the longest distance
between two points ... "
If you have any
questions or
comments
please call
Sega Pinball
Technical
Support toll
free at 800/
542-5377 or
3rdProngi in-state 708/
Required for
345-7700.
Grounding