Star Tech Journal

STAR*TEcH
January 1996
Journal
. . . . . ... ........................................... . ................
SEGA PINBALL APOLW
I
13 MAGNET INTERFACE
How to make a pinball orbit the Moon
TEAM SEGA
Joe Blackwell
Eric Winston
Jay Alfer (artwork)
Ted Kilpin
Sega Pinball
Melrose Park, Illinois
APOLLO 13™
THEORY OF OPERATION
Apollo 13 Playfield Magnet In-
terface and 7-Segrnent Display
Board Diagram (520-5130-06)
We would like to introduce a fea-
ture on Apollo 13 which grabs the
ball off a ramp and orbits it
around the moon dropping it into
the under playfield Trough As-
sembly.
A write to address $3500 can
then take place, with the data bits
present being latched into the
outputs of U2. Bits DO thru D3
are latched to generate the Bi-
nary-Coded-Decimal (BCD)
digit which is visible via decoder/
driver U 1 and the 7-Segment
LED display.
When bit D5 goes high and D4
stays low ( 0 N condition) Q5 is
switched on, turning off Q6 and
resulting in a high drive signal or
voltage atJ2 pin 15.
Digitally this board consists of
output ports that reside at three
dedicated address locations.-
These locations are determined
both by pinout choices (at the I/
0 Board) and by hardware de-
coding on both CPU /Sound and
1/0 Boards.
A CPU write operation to Hex
address $3601 clears the outputs
oflatch U2 (74LS273) (The /CLR
line goes low, and all outputs of
U2 go low.) A write to address
$3600 brings the /CLR line high,
and enables data output from
latch U2. The actual data bits
present during these two write
operations are ignored.
turning Q4 0 N which supplies
5v DC to the collector of Q5 and
the base of Q6. The ON output
of U2 will be low turning Q5
OFF which will turn Q6 ON
which brings the output atJ2 pin
15 low leaving
the magnet OFF.
When bit D4 is high with D5 low
(HOLD condition) Q4 is turned
off, Q5 is turned off, and the (10%
duty cycle) square wave output
of U3 is applied to Q6, resulting
in a 10% drive signal at J2 pin 15.
Data bits D4 and D5 are latched
into the outputs of U2 to enable
the moon magnet. When the
magnet is turned off both Bits D4
and D5 are low which means the
hold output of U2 will be low
The two different drive signals
result in a powerful GRAB effect
and milder HOLD action of the
Moon Magnet similar to pull-in
and hold power in our flipper
coils.
"ROGER THAT HOUSTON!"