Play Meter

Issue: 1979 December 01 - Vol 5 Num 22

By Doug McCallum
How to find those pesky shorts
Editor's Note: Operators still in
possession of some of the electro-
mechanical games may find this
article on shorts helpful. However ,
the information does not apply to
solid state games .
Shorts and their symptoms (circuit
path interruptions due to faults in the
current limiting circuitry - also known
as blown fuses) can be exasperating
little devils to figure out, and I regret
to announce there are no simple
ways to find them.
However , I herein offer some tips
and techniques that should help . I
will limit this essay to 24 volt shorts,
but light shorts (six volt) can be dealt
with similarly .
First , shorts come in different
types : the dead short , the "slow"
short (blows the fuse after a couple of
seconds rather than immediately) ,
and the occasional short (blows fuse
only when the shorted path is turned
on).
Dead shorts can be tough - often
they can't be helped by the schema-
tic . As with any short we use a
breaker .
First look for loose quarters or
hardware lying about , nuts and bolts
seem to fall across relay blades while
quarters usually find their way under
jones connectors and other goodies
near the front , but you never know .
If nothing obvious shows up and you
dori't see any burnt up coils, it
becomes time to isolate the prob-
lem - unplug the playfield .
Short still there? Unplug the
head ... short still there? Time to
check out the mechanical board .
Once you've found where the
short is (say , the playfield) you can
further narrow it down by figuring out
which jones plug carries the shorted
line .
Many machines, especially Bally
and Williams, list jones plug connec-
tions either on the schematic or in the
instruction manual. Once you nar-
row it down to a few wires , you
should have no trouble finding which
one is shorted and where . Just
think - you're done before lunch .
Slow shorts are found similarly but
an ammeter is a better tool than a
circuit breaker because you don 't
have to wait for the breaker to blow .
Occasional shorts are the best.
Generally, you can associate them
with some activity (pop bumpers,
advance bonus, whatever) , which
are simple enough. Sometimes it
involves the scoremotor (reset se-
quence , etc .) No problem : pull out
the scoremeter service jack and step
the scoremotor around slowly by
hand . When you find which stack
controls the short , look it up . Most
games have scoremotor contact
listings either in the schematic or the
instruction book .
If these basic maneuvers fail , well ,
take your lunch break and stick with
it - it's time to start unhooking wires .
When you have something like a ten
point line shorted you have no
course but to disconnect and thus
isolate areas of the machine and , ta
da , if you keep narrowing it down ,
you 'll find it , by golly .
Technical tip on Atari's LUNAR LANDER
There is a letter in a square on the bottom of the main PCB near the
edge connector : A , B , or C . If your board is A or B , perform the
following modification to protect the 4016B in location A 12 from excessive
input voltage .
Install (2) ln914 diodes next to the device in location B-11 as shown .
B- 11
- -•Ill Ed ge connecto r
AD561JD
-1
.1 uf
Add { 2 ) 1N914's
r
'It Band same end .
.;j
-c=o-)
---1)1-
Note : DO NOT replace the 4016B's with 4066's . Switching characteristics
of the 4066 make it unacceptable for use in sample and hold circuit
applications .
The straight poop on flippers:
Why 'dis' makes 'dat' work
It is all well and good to know that ,
"if I fix dis ... den dat will work ," and
the game will be up , but it is often
helpful to know why " dis" makes
"dat'' work . Here's what's happenin'
in a flipper .
The flipper coil consists of a
double winding, two coils in one, so
to speak . First , a "pull-in" winding
constructed of heavier gauge wire
and fewer turns . Second , a "hold -in"
winding is bypassed by the normally
closed end of stroke (EOS) switch.
The pull -in winding draws higher
current , producing a very strong
Ft..IP PE!R
Bun orJ
pull-in stroke . However , if this were
to remain energized (the player
keeps her/ his finger on the button,
say) it would soon overheat.
To reduce the high current after
the strong pull stroke is completed ,
the hold winding is put in series with
the pull -in winding by action of the
opening EOS switch that had been
bypassing the hold coil. The extra
winding in series raises the overall
resistance of the coil thus lowering
the current. Believe me , it works that
way .
With both windings "on" the
F t. IP P ER
C ou.
~--------------~~Y.------------------~
resulting magnetic field is much
weaker but is sufficient to hold the
flipper up .
Thus we can see that if the EOS is
dirty , open, or disconnected we will
have the low current or "weak"
condition . Likewise , if the hold -in
winding is open we will get a
chattering flipper . The pull -in coil
works but as soon as the EOS opens
there 's nothing to hold the flipper up
so the EOS closes again ... and
again ... and again ... Of course , if the
pull -in winding is open - nothing will
happen .
How to cure the weak flipper:
- The EOS switch should have a
great deal of "scrub" and should
open just before the flipper is fully
up .
- The flipper return spring should
not be too strong - remember the coil
has to fight this spring to move the
flipper .
- Make sure the solenoid plunger
has not " mushroomed"- just a little
bit of friction can really weaken a
flipper.
- Lube: the nylon bushing and the
linkage may be oiled but never the
solenoid plunger.
Industry tribute to Fishman
nets Israel $5.5 million
An outpouring of financial support
for Israel's economic development
was demonstrated in Chicago recent-
ly at a national dinner which honored
William S . Fishman , chairman and
chief executive officer of ARA
Services , Inc ., a diversified services
management company.
The tribute resulted in purchases
of $5 .5 million in Israel Bonds and
other securities.
The dinner was part of a
nationwide effort by the Israel Bond
Organization to provide Israel with
investment dollars through a $1
billion "Economic Development for
Peace" loan . The new issue , Sixth
Development State of Israel Bond
issue, was launched to help Israel
develop the Negev and undertake
other projects necessary for the
implementation of the peace treaty .
Ephraim Evron , Israel's ambas-
sador to the U.S. , presented his
country's " Prime Minister's Medal" to
Fishman , commending him and the
bond organization for the "tremen-
dous contribution" they have made
to the future of Israel.
Meyer Gelfand , chairman of the
Macke Company and dinner chair-
man , told the 600 representatives of
the automatic merchandising , linen -
laundry , periodicals distribution , and
health services industries who were
present that bond purchases were
"proof of the wholehearted support
of the business community , both
Jewish and non -Jewish , for Israel's
progress toward peace and economic
security ."
Howard C . Miller , president of the
Canteen
Corporation ;
Marvin
Heaps , president of ARA Services,
and Alvin W . Cohn , president of
CFS Continental , also participated in
the program.
The $1 billion " Economic De -
velopment for Peace" loan will help
to provide investment dollars for the
building of an entire new infrastruc-
ture in the Negev . Industries , jobs ,
roads , communications , transporta-
tion and energy , are to be provided
at a cost estimated at billions of
dollars .
Some of the priorities for which
Israel bond dollars is needed include
energy , water projects , telecom -
munications , and transportation .

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