(Continued from page 40)
tech Power, solve these problems
by :
a)Using 10-year life computer-
grade filter capacitors ,
b) Using larger rectifiers operating
at about half thei r rated current or
less, and
c) Using higher powered, metal -
cased , hermetically sealed power
transistors and regulators.
Considering the high loss of
revenue when a game is not
operating, plus the high cost of
service calls and the increasing
complexity of video game circuits, it
pays to use the higher quality
computer-grade power supply . The
higher quality power supply usually
adds less than 0.5 per cent to the
cost of the video game but it
virtually eliminates failures .
Therefore , when a video game
has one or more of the above
problems, here is what can be done
to resolve each problem :
a) Noise Problem: A commercial
AC line filter connected between the
AC input of the power supply and
the line cord will usually correct this
problem .
b) Frequent IC Failures: Connect-
ing a GE metal oxide varistor (M OV)
across the transformer primary and
an overvoltage protector (OVP)
across the output of the power
supply will usually protect the IC' s.
Caution! Do not use an OVP unit
unless the power supply has fold -
back current limiting to protect it
when the OVP operates .
c) Low Line Voltage: A step-up
autotransformer 110 to 120V or 115
to 120V) will resolve this problem,
although it may cause problems if
high line voltage also occurs . In this
case , an AC regulating transformer
will solve the problem , although it
would be cheaper to replace the
power supply with a higher quality
power supply which would have a
wider input voltage range to com-
pensate for low and high line
voltages automatically .
d ) Power Supply Failures : Heat is
the biggest enemy of power sup-
pl ies. A number of cooling holes in
the cabinet around the periphery of
the power supply and vent holes
above the power supply in the top or
sides of the cabinet will often
provide enough cooling to save the
marginal power supply . Care must
be taken to locate the holes to
prevent spillage into the cabinet,
and they should be screened to
prevent tampering .
SUMMARY
Usually the best solution to
persistent problems associated with
power supplies in video games is to
replace the marginal power supply
design with a high grade computer-
quality power supply. M ost cabi -
nets have more than adequate room
and the wiring is quite simple . Be
sure to observe polarity on the
power supply output .
The high
quality supply will usually cost less
than $50 .00 and can be installed in
the field .
Let's
help
each
other.
~Od
neighbor.
+
The Am«icGn Red Cross
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