.,.__"'TAR TECH JOURNAL
April 1994
WILLIAMS
STAR TREK: NEXT GENERATION
OPTICS
Evan Wessell
Mercury Amusement
Havertown, Pennsylvania
BALL DETECT
OPTICS
I noticed with Star Trek: Next
Generation that Williams is using
a new "Eddy Sensor" in the flip-
per return lanes. This is a small
ball detector located under the
playfield that eliminates the need
for a wireform switch. Ours went
out of adjustment already, but it's
a snap to adjust. (There is a trim-
mer on the tiny interface board).
Since there is no real need for a
fancy sensor switch in this loca-
tion, I assume it's somewhat of a
test run for further use in the fu-
ture. (If the outlanes fail, big
deal).
There are banks of optical
switches in the bottom ball
trough and left side vertical
upkicker troughs. An LED
mounted on a green PC board
shines through a hole in the
trough turning on a photo tran-
sistor mounted on a blue PC
board. The Led transmitters are
clear and the phototransistors are
black.
SENSORS
Fortunately, these switch pairs
will read in switch test. The prob-
lem is determining which side is
bad, the Led or the
Photo transistor.
bration in these troughs, I would
expect most failures to be from
broken Led and Transistor legs,
broken legs on the 270 ohm/2
watt resistors, or broken wire
connections.
STOCK
The wiring gauge looks to be too
narrow for this application, but I
hope I'm wrong.
I would recommend stocking the
following parts for future service:
• A-16927
LED PCB for trough.
1
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As far as the proximity sensors in TESTING
• A-16926
1
Twilight Zone, I have not gotten The LED can be tested by shin-
Phototransistor PCB for i j ~
them to work for more than a ing it on an "Infrared Detector
trough.
week, even after CAREFUL ad- Probe", which is a strip of plastic
i
justment. This is not too critical, that will glow orange when infra-
j
• A-16909
]
but pinheads tend to notice. A fix red is present. You can get these
Individual Phototransistor 1
i
would be nice. Star Trek: Next for a few dollars from MCM Elec-
assembly.
:I
Generation makes extensive use tronics (1-800-543-4330), Stock
:~
i =:~
of optical sensor switches instead #72-003. You should observe a
• A-16908
l
of microswitches. I suggest that voltage change from about 1 to
Individual LED Assembly. J
]
parts be stocked to prepare for 12 volts across a good
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possible failures. Although the phototransistor. That's easy to
• 270 Ohm, 2 watt resistor. l
L. '
microswitches have been fairly check.
... ,.. . .•.•
• •,•. :xs..-. :-: . -. ~ ~~-....w:::~
reliable in the past, 6 ball multi-
ball may be handled better by BAD VIBES
Oh well, progress requires
Since there is a great deal of vi-
non-mechanical means.
some effort...
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