Star Tech Journal

STAR*TEcH
Journal
March 1996
':Just the Facts, eh?"
John Liikala • Canadian Amusements • Burnaby, BC • Canada
WILLIAMS WPC POWER DRIVER
CPU RESETS SYMPTOM
PROBLEM
When the pinball is in play, the
game will randomly reset. Or,
resets while sitting in the attract
mode with no play.
NOTE2
Another reason these bridge rec-
tifiers fail is that the screws that
hold the heat sinks on, come
loose and then the bridges over-
heat. Be sure to visually check
these areas.
A-12697-3
WPC Power DrlYer Assembly
SoumoN
Check to see if there is low AC
voltage present at the outlet. If
the AC voltage is correct (ap-
proximately 115Vac - 120Vac in
North America), then change out
both bridge rectifiers BRl and
BR2. These are the ones with
heat sinks mounted on them.
If the AC voltage is lower than
recommended, then find an out-
let with the proper voltage and
retest the operation of the pinball.
If the resetting continues, then
change the bridges as above.
NOTEl
BRl supplies the 18 DC volts
BR2 supplies Ql, the +5 volt DC
regulator which supplies power
to the digital circuitry. See figure
for bridge rectifier locations .
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