Star Tech Journal

STAR*TECH
Journal
July 1996
SEGA PINBALL WHITE STAR SYSTEM
1/0 POWER DRIVER BOARD
THEORY OF OPERATION (PART FouR)
Sego Pinball continues its ongoing instructional series explaining their newest pinball hard-
ware system: The White Star System .. This issue's installment is on the "Lamp Matrix" circuitry.
TEAM SEGA
Joe Blackwell, Eric Winston
Ted Kil pin, Jay Alfer
Sega Pinball
Melrose Park, Illinois
J12 has 10 Low Side Drivers for
the lamp strobes which consist of
STP19N06L MOSFETS (these
are 19amp / 60volt N-channel
MOSFETS which can also be sub-
stituted with the STP20N10L
MOSFETS used for our Sole-
noid Drive Circuits).
LAMP MATRIX
I
eating a reset condition most
likely due to a communication
problem between the CPU
J13 has 8 High Side Drivers
with each having a status indica-
tor. All the status indicators are
logically 'OR'ed together and fed
back to the CPU Board.
Only one lamp strobe should be
low at any time. The scanning of
the lamp strobes keeps the I/0
Driver Board from resetting.
If the watchdog is not being fed
by the scanning of the Lamp Ma-
trix (more specifically Pin-19
DRV0 of U6 must be toggling
once every 50ms to prevent the
watchdog from resetting) then the
Red LED L204 (on the 1/0
Board) will begin flashing, indi-
The scanning of the Lamp Ma-
trix is controlled by the CPU
Board through Ribbon Cable
Connector J 1.
The status can identify open
loads (for example open lamp
filaments or intermittent connec-
tions) and short circuits.
Board and the I/0 Driver Board
(this could be as simple as the rib-
bon cable being disconnected).
These drivers are also short-cir-
cuit protected. They thermally
sense an over-current condition
and will shutdown the output
while at the same time triggering
the staus line.