Star Tech Journal

STAR*TECH Journal
January 1987 (12)
Various And Sundry Problems
Concerning Electronics, Part 2
By Sam Cross
Godwin Distributing Co.
North Little Rock, Arkansas
STAR-IITECH JOURNAL has asked Sam Cross to
reply to an assortnent of service problems
most often encountered in everyday
maintenance of coin-operated electronic
entertainment equiµnent. What follows is
the second in an ongoing series of
discussions identifying the most common
trouble areas as seen by the service
community of our Industry.
LOAJ)
LIN€ FIL1£R.
I..AST ISSUE: Power supply voltage
neasurenents and adjustments. Also, p:>wer
terminals on ICs -identification and
precautions.
LINE Fil,~
If you don't have a line filter on the
game you have or are converting, it would
be adviseable to add one. They go in the
"AC" line voltage as shown in the
illustration.
These devices suppress voltage spikes that
ride in on the AC power line. The filter
doesn't allow large voltage fluctuations
to enter the game.
The filter's purp:>se is to allow p:>wer to
the game witoout the spikes that may come
from refrigeration units starting or
stopping -or any other heavy current
demand loads, which could cause AC line
variations to your game.
IDTs
Sonetirnes these spikes can be quite large
and can even knock out your switching
p:>wer supply. As an added protection, I
recornrend an 1!'iJV protector rated at 130VAC
available from Radio Shack. You can put
these across the "Load" side of the line
filter or across the 120VAC input
terminals of the switching power supply.
These 1!'iJV protectors start to draw current
away from the load, at any voltage around
130VAC and essentially act as a short to
voltages above 130VAC. They are
particularly effective against lightning
strikes and static discharges.
TIB--IDiR,
en
sone games such as PAC-MAN, and MS.
PAC-MAN (which use basically the same
board), or those garnes which are using
piggyback boards such as Merit's
A
countertop video garnes, (I'm referring in W
particular to the systems which have added
small circuit boards connected via
contacts to the motherboard), they often
display logic problems due to the
piggyback boards working loose from the
rrotherboard.
In these cases, I suggest after having
these piggyback boards loose, to then wrap
them to the rrotherboard -if you are able
to do this. If the tie wrap holes are not
available or not large enough to
accorrodate the tie wraps you have at hand,
then drill them out (if you are able or
find an appropriate place on the lower
board to drill some holes to run these tie
wraps) , even if you may have to rewire
some of the traces you cut.
If even this isn't p:>ssible, think of sone
external bracing to hold in the piggyback
board to make good contact -if that is
your problem. Often cleaning the contacts
of the piggyback board before you tie wrap A
it in, will assure longer lasting
W
performance.
NE>cr' ISSUE: Heatsinks and Ventilation.
Also, Fuse and Plug data.