Star Tech Journal

May 1sas (7J
Let's face the fact that the industry only
has one universal video garre test fixture
and rrost of you find the thought of buying
one too extravagant. 'lhere is a lot to be
said about doing your own board repair but
tam here to talk specifically about
pinball boards.
'lhe best test fixture you have available
to you at this time is the garre itself.
Everything you need is present within the
garre. 'lhe only additional item required is .
the proper knowledge and tools to do the
job. I know it is somewhat awkward but
that is all you have to work with right
now.
Most of you know the board replacement
method of troubleshooting a pinball garre.
'lhis method could be used to identify the
problem board. '!he one major difference
would be that you would atterrpt to repair
the problem board once you have identified
the problem. 'lhis will take rrore time in
the older systems because of the nunber of
boards. 'lhe new systems make it necessary
to realize which section of the board is
at fault. You can obtain a better
understanding of the new one board systems
if you are familiar with the old nultiple
board systems.
'lhe new systems are really the sarre basic
system laid out on a single board. You now
have a sound section instead of a sound
board or a solenoid driver section instead
of a solenoid driver board etc.
Many problems with pinball garres are
fairly sirrple to repair. You can identify
them by a problem that originated on the
playfield and caused a portion of the
board system to fail. For example, a
shorted solenoid on the playfield can take
out a driver transistor or rrore conponents
in the circuit. 'lhis type of problem is a
good place to start if you are new at the
repair level. ~ing is learning and if you
keep at it you will eventually learn what
you need to know.
WI'E: last rronth, I wrote an article about
the first AOIB show and it appears I
received some incorrect information. Data
Fast is WI' offering~ FU MASTER,
ca-tMAN[X) and SHOOIOUT as conversion kits.
STAR*TECH Journal
:Euwer 5ua>ly conversions
By Janes Beck
Greater Southern Distributing Co.
Atlanta, GA
Everybody is doing it lately, converting
those broken down DRAGON'S IAIRs. Why not,
take out the old boards and the disk
player and there is plenty of room for the
new boards and an RF cage. Unfortunately,
the National Power Technology power supply
used in most of the DRAGCN's LAIRs can
only supply +5 volts at a few amps, and
doesn't have any +12, -12, or -5 volts.
~n•t despair and don't go buy that $50
switching regulator. For a few dollars in
parts, and a little patience, the existing
power supply can be rrodified to rival the
specs of any switcher you could buy.
First, let's get a couple 100re
the +5 section. Olange R2 to a
watt resistor, and R3 to a 560
watt resistor. Now you can get
out of the +5 supply.
amps out of
0.1 ohm 5
ohm 1/4
5 to 6 amps
Next let's get some +12. Pin 7 of Jl has
+25 volts unregulated on it. Mount a 7812
regulator to the chassis and run the +25
and a ground to it. 'lhere is our +12
volts. Need -5 and/or -12? Pin 8 of Jl
conveniently supplies us with -25 volts
unregulated. Cnce again the 3 terminal
fixed regulator comes to the rescue. A
7905 and/or a 7912 will do the job nicely.
When all of this is done, you have a power
supply that can supply +5 volts@ 5 amps,
+12@ 1 amp, -5@ 1 amp, and -12@ 1 amp.
'!his is adequate to run just about every
conversion kit on the market today for the
cost of a few dollars and about 1/2 an
hour of labor.
Next 100nth, I will cover methods of
obtaining negative voltages from a supply
that has only positive outputs.