Star Tech Journal

OCTOBER
STAR...-TECH JOURNAL
1 998
SEGA PINBALL WH11E STAR BOARD SYSTEM:
How ro TROUBLESHOOT Cons AND Co1L DRIVERS
Team Sega Pinball
Joe Blackwell, Eric Winston,
Doug Lemons, Jay Alfer
Sega Pinball
Melrose Park, Illinois
SUBJECT
The White Star Board Sys-
tem: How to troubleshoot
Coils and Coil Drivers
We have calls from time to
time asking how to determine
if a particular Drive Transis-
tor (for Flash Lamps & Coils)
on the I/O Board is working.
By first troubleshooting in the
Portals® Diagnostics using
Coil Test & Switch Test, you
have determined that the Coil
is not functioning, however,
the corresponding switch is
working properly. For an-
other helpful troubleshooting
tool enter Portals® Diagnos-
tics and activate the Dr. Pin-
ball Icon and open the Coil
Flow Chart Menu and answer
the questions. With the Coil
not operating in Play or Test
Modes, we need to determine
if the Coil OR it's Transistor
on the I/O Board is bad.
Before troubleshooting the
I/O Board, first determine all
associated fuses are good,
then if the Coil is good or bad.
To do this, we need to check
if the Coil's Load Voltage is
physically present at the Coil.
(Note: Ensure the Coin Door
is closed or the Power Inter-
lock Switch is pulled out).
With a Volt Meter, you can
measure this voltage with the
Positive ( +) Meter Lead at the
metal tab of the Transistor on
the I/O Board and the Nega-
tive (-) Meter Lead to Ground
to the metal ground strapping
and with the other end of the
Jumper touch the metal tab
of the Transistor. If the Coil
energizes, you know it is good
( the Coil has voltage and that
the Coil will fire if
GROUND is present).
So, we can now test I/O
Board to determine if the
Transistor has failed. Let's
use a VUK Coil as an ex-
ample. Let's say this VUK's
Transistor is positioned at
Q14. There are two types of
Transistors that are used to
drive devices with the White
Star Board System™.
(for a good ground use the
metal ground strapping inside
the cabinet or the metal back
plate in the Backbox). You
should see 72 to 76 volts DC
on the MOSFETs and 20
volts DC on the TIPs. If the
voltage is good, next use a
Jumper Wire to test fire the
Coil. Take one side of the
Jumper Wire and connect it
For High Current Solenoids
(Flippers, Auto Launch,
·Slingshots, etc.) a MOSFET
Transistor STP20N lOL is
used as a Drive Transistor
(Ql-Q16); and, for Low Cur-
rent Solenoids (Ramp
Diverters, Flash Lamps, etc.)
a DARLINGTON Transistor
TIP122 is used as a Drive
Transistor (Q17-Q32). Both
Transistors MOSFET and
DARLINGTON are used
simply as a switch to ground