Star Tech Journal

Issue: 1986-June - Vol 8 Issue 4

STAR*TECH Journal
June 1986 (7)
SPEED B00GY U/R WISE BI\RS IN DISPIAY.
If your SPEED BUGGY upright displays dark
lines that weave through the picture, you
can eliminate them by installing a jUill)er
wire onto the Power Supply asserrbly. This
was recently discovered in Manufacturing
\I.hen several ganes suddenly came up with
this problem, and it was due to a ground
jUill)er that was accidently left off the
Power suwly. We do not think any games
have shipped like this, but we will pass
along the infonnation just in case.
'!he problem stems from the FRAME GROUND on
the switching Regulators not being
jUill)ered to the OC GROUND outputs on the
switching Regulators. Refer to figure 4
for jUill)er infonnation. Install junpers as
shown if your game. does not have them.
Atari STAR WARS High-Voltage Board
by Avery Petty
A.P. Engineering
Huntington Beach,
CA
Recently, I repaired a whole fleet of
Atari STAR WARS. I sent soneone to the
distributor to get the 'hard-to-find' high
voltage transistor BU406D. He cane back
with a BU406, no "D". The "D" nust appear
on the transistor. It means there is a
high voltage diode in the package. So
beware, even the distributor can goof!
What will it cost you? Your game maybe.
Witoout the diode, using the BU406, the
high voltage will work for awhile, but
will bum up the flyback transformer which
cost $90.00!
If you are repairing a High Voltage board,
EY05020
ON
V.filjS
and after replacing all the capacitors,
the two 24 volt regulators, and related·
])C ON (y
8
0
V.AI>J
0
121/A.2A
t.S
r
+v
L
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r-K-1
INPUT
Ltc2
parts and the the high voltage transistor
with a BU406D, and you still don't have
high voltage, and don't know why, you can
be sure it's your flyback transformer. If
in doubt, pull it out and put it in a
working STAR WARS and see, it will only
take 5 minutes.

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AC
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figure 4
SPEED BUGGY U/R FUSE IABELS.
D.le to an oversight on Data East's part,
it is possible that several SPEED BUGGY
uprights went out with the wrong fuse
rating labels on the switch Bracket. They
state that Fuse 1 = 1 anp fast and Fuse 2
= 3 anp fast. These should actually
indicate Fuse 2 as a 7 anp fast, Fuse 1 is
labeled correctly. Please refer to page 9
of the SPEED BUGGY Operations & Service
Manual (PN 780-0035-00) for xoore info.
When you finally fix it, put a fan under
the board -nounted on the wood rail the
board is xoounted on, blowing on the High
Voltage board. '1his is sonething that
should be done to all STAR WARS, because
the flyback is the rost expensive part
there.
If your high voltage won't get up to at
least 19,000 volts, }!OU may have a bad
tube. look for real bad phosphor bum or a
color missing.
SERVICE NAIUAL
Initructionel end reference manual
entitled ELECTRONIC GAME REPAIR covering
such subjects es: Basic Electronics,
Semiconductors, Video Gama Systems,
Electronic Pinball Systems,
Troubleshooting Techniques, Tools and Test·
Equipment, Schematic Reading and more.
This 8-1/2" x 11" manual contains 85 pages
of technical information for the servicing
of electronic amusement games and is
priced at ,24.95 plus ,2.50 shipping.
Distributed by STAR*TECH JOURNAL.
June 1986 (8)
STAR*TECH Journal
Negative Voltages
From Positive Supplies
By Janes Beck
Greater Distributing
Atlanta, GA
co.
This nonth we will work on getting
negative voltages from a supply that
offers only IX)Sitive outputs. In this
colunn, we will concentrate on linear
supplies; that is IX)Wer supplies that use
a step down transformer and a series pass
transistor for regulation.
Fig. 1A and 1B show the two nost corrrron
rectifier circuits. To get a negative
voltage from these just tap into the low
voltage AC supply and make an identical
circuit with the diodes and capacitor
reversed. Fig. 2A and 2B shows this.
~
.
1'0 fOS1T1V£
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-
R€.S.tl01TOR
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The only real design consideration is
which AC supply to tap into. I have found
the +12 unregulated supply is usually
best. This will give you enough voltage to
use fixed regulators such as a 7905 or
7912 to get the output voltage you need.
It should be noted that for short circuit
protection a fuse can be added to one of
the AC input lines. A 1-1/2 MDL should
suffice.
~
--
VOLUMES/ISSUES
Some back issues and complete volumes
remain in our inventory. Complete Volumes:
$42 ($US). Single Issues: $5 ($US).
- -
2.b
The filter capacitor should be 2000uf or
greater with a working voltage at least
20% higher than the continuous unregulated
voltage.
Well, that will wrap it up for this nonth.
I hope I have saved you a few dollars and
maybe a few headaches.
Next nonth, we will work on getting
negative voltages from the infanous
switching regulator when it has only
IX)sitive outputs.
16
2a..
Since negative supplies are usually used
to power op-anps in the audio section, the
current demand is very low. This gives us
a lot of design flexability. The
rectifiers can be just about any 1 anp
general pur:[X)se type. 1N4004s work great.
*** Send self-addressed stamped ($0.39)
envelope (#10 or larger) far complete
index of all articles covered since Mar79.
➔ To P.,5tTl\le'
t(E'',U{ATOR.
C.
-
ro#.1€f,ArlV8
/l€"f/U(.dTlJ~
- -
Availability: Complete Volumes (twelve
issues bound under one cover);
#1 (Mar79-Feb80),
#2 (Mar80-Feb81),
#3 (Mar81-Feb82),
#4 (Mar82-Feb83).
Single Issues:
May84, Jun84, Jul84, Aug84, Nov/0ec84,
Jun85, Jul85, Aug85, Sep85, 0ct85, Nov85,
Dac85, Janas, Feb 86, Mar86, Ap r86, Mayas.

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