Star Tech Journal

Issue: 1987-July - Vol 9 Issue 5

July 1987 (3)
STAR•TECH Journal
Atari DUNK SHOT New Rom
Updates
By
Al Vemon, Field Service Tech
Atari Ganes Corp.
Milpitas, califomia
We have discovered a credit error in the
DUNK SIDI' software which allows unlimited
Free Credits. This problem has been
resolved by a new set of Roms which will
be available the week of June 15th.
Until you receive the new rom.s, we ask
that you tum off the "Winners Advance"
and "Gane Continuation" options; SW2, #1 &
i8 "OFF." We have found that this free
credit bug occurs only when these two
options are tumed "00".
lk>wever, with the new Rom.s these problens
will be corrected and we reconnend that
once you install the new Rom.s that you
reactivate the "Winner Advance" and "Gane
Continuation" features.
The new Rom.swill be available through
your distributor on a credit-upon-retum
basis.
For further information, call Atari Games
Customer Service at 408/434-3950,
Monday-Friday, 7:30 a.m. - 4:00 p.m.
Pacific Time. Telex 5101007850.
Premier SPRING BREAK Game
Prom Change
By
Adolf Seitz
Premier Technology
Bensenville, Illinois
Based on valuable input from our
distribution network corrbined with test
feedback from our operators, Premier
Technology has issued a SPRIOO BREAK game
prom change. This new prom change gives
you the option of "two games in one."
switch #31 On:
Continuous multi-ball action remains.
switch #31 Off:
One ball released per ball in play
(nulti-ball nust be eamed).
The new proms (706/2) will be incorporated
into the new SPRIOO BREAK production run.
You may obtain the new proms for
SPRI~ BREAK sanples by following our RCN
procedure ( 30 Day Advance Replacement
Policy).
Wl'E:
If you have any questions conceming the
change, please call Premier Technology at
312/350-0400. Telex 72-8463.
IIDEXES of paat. 1••••• will be published
in an upcoming issue. Volumes 8 through B,
(Jun85 - Feb87), will ba indexed for
faster access to filed information. Tha
index will be the center pages for easy
removal.
Also, we're working on a new monthly cover
design which will include the service
topics covered inside for fast look-up.
We're listening to your suggestions.
TAR•TECH JOURNAL, July 1987, Volume 9,
, umber 5. Copyright (c) 1987 by Star Tech
Journal, Inc. All rights reserved. Address
inquiries to: PO Box 1085, Merchantville,
NJ 08109. Phones 809/882-1080.
Subscription rates: USA ,ss.oo. Canada/
Mexico •83.00. Other Countries •98.00.
Please remit payment in US funde.
PDBTIIA8TER1 B••d alldreaa oll••a•• lo
ITAR•TECH JDURIAL, PD lox 1011,
••r•ll••t.w1lla, IJ 01101. STAR•TECH
JOURNAL (ISSN 0739-1048) is published
monthly by Star Tech Journal, Inc., 18
North Centre St., Merchantville, NJ 08109.
Second Class postage pending at Camden,
NJ. Publisher/Editors James Calore.
STAR*TECH Journal
July 1987 (4)
Inside Switching Regulators
(Part 4)
By Janes Beck
Greater southern Distributing Co.
Atlanta, Georgia
Vsuffl!!I
OK, what is control logic? In our case it
is a pulse width IOOdulator (PWM). What's a
pulse.width IOOdulator? Figure 1 is. What
does it do? It responds to a change on its
input by changing the duty cycle of its
output.
ERIIQR .AMPLIFIER
If you will look at figure 1 you will
notice that the circuit is made from two
OP amps. One is used as an error amplifier
and the other is the IOOdulator. The error
amplifier uses an input voltage sampled
from the voltage we want to regulate and a
reference voltage.
As in linear regulators, the reference
voltage is a "rock steady" constant that
is used to conpare to the output voltage,
so corrections can be made. The IOOdulator
is another OP amp that does not have any
negative feedback, this means it is acting
as a conparitor. It takes the output of
the error amp (marked Ve in figure l} and
conpares it to a sawtooth wave applied to
the "-" input.
In summary, a sample of the regulated
output is applied to the error amp. The
error amp then outputs a proportional
control voltage that is then applied to
the IOOdulator. The IOOdulator conpares the
control voltage to a sawtooth wave. When
the amplitude of the control voltage is
greater than the sawtooth wave, the
IOOdulator abruptly pulls its output to the
negative supply rail, and when tbe control
voltage is less than the sawtooth wave,
the IOOdulator swings to the positive rail.
-A_.,....,~__,-A....,co~-\-n,\yoltOl\e
V
's--...,-r-t"
In our situation the negative supply rail
would be ground. Figure 2 shows how the
control and sawtooth wave inputs effect
the output of the IOOdulator. This effect
is exactly what switch IOOde regulation is.
The IOOdulator output can then drive
current amplifiers and ultimately the main
power switching transistors.
That is all fine and dandy, but to get ou~
particular supply up and running we not
only need the pulse width modulator in
figure 1. We need a reference voltage,
sawtooth generator, circuitry to convert
the PWM output to two conplimentary
outputs for our switching transistors, and
current amplifiers.
1~~
1Nv
REF
INPUT INPUT OUT
NON
ll'IV
FEED
INV
INPUT BACK
IN P IJT
CXJTPUT
CONTROL Vee
DEAD
TIME
COITROl.
CT
Fis 3
CZ
E2
El
RT
GND
Ct

Download Page 3: PDF File | Image

Download Page 4 PDF File | Image

Future scanning projects are planned by the International Arcade Museum Library (IAML).

Pro Tip: You can flip pages on the issue easily by using the left and right arrow keys on your keyboard.