Star Tech Journal

STAR*TECH
Journal
CID
March 1996
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SEGA PINBALL WHm- STAR SYSTEM
1/0 POWER DRIVER BOARD THEORY OF OPERATION
(PART ONE)
TEAM SEGA
Joe Blackwell, Eric Winston,Jay Alfer, Ted Kilpin
Sega Pinball, Melrose Park, Illinois
5V SUPPLY
An AC voltage of approximately
9V comes into the board at U 17-
( 1-4)] this AC voltage is then full-
wave rectified by bridge BRDG
21 and filtered by capacitor
C203.
The resulting voltage is 11 VD C
which is inserted into a linear
voltage regulator for the output
of 5VDC. This 5V regulated volt-
age can be adjusted by potenti-
ometer Rl 16 the voltage should
be set to 5.00V.
Besides powering the 1/0 Board
the regulated 5 volts supplies
power to the CPU & Sound
Board Gas Plasma Display and
Plasma Controller Board. Power
for these devices comes off the
1/0 Board on U16-(4-8)].
+5 + 12 +50V + 18V +20V
LED INDICATORS:
These DC voltages are derived
on the 1/0 board by rectification
and filtering. Each has a LED
indicating that power is being
supplied to each of these voltage
sources. The -12V supply comes
from the same transformer wind-
ing as the + 12V thus it does not
have a LED indicator.
** Note - The +50V & +20V power sources are turned off by the
interlock switches when the coin door is open.
LED
Supply Voltage
L2
L201
L203
L200
L202
Bridge Rectifier
+5V
+sov
+12V
+20V
+18V
GENERAL ILLUMINATION (G.I.):
J15 has 6VAC switched on and
off by a relay on the 1/0 Board.
The relay is controlled by Q200
which supplies power to the 24 V
coil winding to activate the relay.
There are 4 taps on J 15 each
fused at SA for this 6VAC source.
The traces have all been beefed
up to prevent overheating and
board damage which can happen
in older machines.
BRDG-21
BRDG-1
BRDG-3
BRDG-2
BRDG-20
Fuses
F23
F6,F20,F21
F8,F9
F7
F22
TusT PmNTss:
Test Points TPLl(FET-High Cur-
rent) & TPL3(TIP-Low Current)
These are wire loop test points
connected to 5VD C through
pull-up resistors R300 and R302.
They can be used to trigger the
high current and low current
drive transistors by using a
jumper wire to connect the test
point to the base or gate resistor
in that particular drive circuit.
NEXT MONTH:
We will take a look at Address decoding and reset circuitry.
I
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