Star Tech Journal

July 1987 (7)
STAR•TECH Journal
~
To check a potentiometer for noise,
connect one probe to the wiper and the
other probe to either end, then rotate the
pot through its range while observing the
display. Refer to fiqure 6.
Bally Midway STRANGE SCIENCE
Ball Trough Kit
By
Amold R. Aarstad
Bally Midway
Franklin Park, Illinois
SUBJOCT: Multiball Problems
F'l6UR.E '
'iu, rin•,oAJ
\
To distinguish NPN from PNP transistors,
rove the red probe to the transistor base
and the black lead to either the emitter
or collector. If the knee opens downward,
the transistor is NPN1 if the knee opens
upward, the transistor is PNP. The same
techniques can also be used to determine
diode direction.
Occasionally it is necessary to desolder a
part to determine its condition. I have
~found that in such instances a conparison
check with a known good board does away
with the need to desolder the suspect
conponent. I recomnend the conparison
method, which appears to give conclusive
results.
Very small value capacitors will appear
open rather than reactive, and very small
inductors will appear shorted rather than
reactive. In mst cases, however, this is
imnaterial, since it is still possible to
detect a shorted capacitor and any open
inductors. Cbviously an ohmmeter could do
no better than the component analyzer on
such components.
There is, however, a method for regaining
the active Lissajous.for observation of
these small COil{)Onents when that is
desired1 merely increase the gain on the
oscilloscope to obtain the desired
anplification.
The first time you use this analyzer on a
~ells Gardener XY mnitor or a Sente
' 'ROller Ball, you' 11 be amazed at how
SIIDOth the work flows.
\
Next time we'll talk about another simple
project to make bench work easier.
Maintaining the Bally tradition of the
best product support policy in the
Industry, we are supplying at no charge a
STRANGE SCIENCE ball trough kit.
The initial shiillellts will begin
imrediately to help resolve nultiball
problems experienced by some of our
customers on S'IW\llGE SCIENCE.
The kit will consist of several new parts
producing a reliable assenbly, but_st~ll
requiring some use of the small existing
parts on the playfield. Please examine the
detailed instructions before discarding
parts from the old assenbly.
we thank you for your cooperation
and
apologize for any inconvenience you may
have encountered.
For mre info, contact your Bally Midway
distributor or Bally Midway 312/451-9200,
Telex 72-1596.
STAR•TECH JOURNAL 8ubaar1pl1an
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