Willianis System 11 Changes:
Identifying 11A, 11B And 11 C
Greg McKay
Williams Electronics Games, Inc.
Chicago, Illinois
SUBJECT
The following description of changes that have been made to the CPU Board from
System 11 to System 11 C may help you recognize the CPU Board used in your game.
SYSTEM
11
(p/n D-10881- Game Number)
System 11 uses a 7-segment LED
to display the game's diagnostic
codes. This CPU contains the
amplification circuit for the Sound
Board and a complete, but un-
used, opto switch circuit.
SYSTEM
11A
(p/n D-11392- Game Number)
System 1 lA uses 3 LEDs to replace
the 7-segment LED (and its related
components) for the game's diag-
nostic code display.
The special solenoid
changed. Pins 6 and 7 on jack
1Jl8 were connected to ground.
Zener Diodes (1N5234, 6.2V) ZR3-
ZR8, were added.
In the logic circuit, Wl6 and Wl 7
were added to ground pin 38 of
Motorola microprocessors. If a
Motorola microprocessor is used,
Wl6 and Wl 7 must be connected.
If any other brand of microproces-
sor is used, Wl6 and Wl 7 must be
disconnected.
SYSTEM
118
(p/n D-11883- Game Number)
Note: Changes to System 1 lB oc-
curred in two phases.
Phase 1
System 1 lB modified the CPU
further. The opto switch circuit
and SRC6, as well as the sound
amplification circuit, were re-
moved.
Phase 2
The layout and type of the switch
circuit transistors changed. Q42-
Q49 changed from two rows of four
transistors to a single row of eight
transistors, as well as from
2N3094 to 2N5550.
SYSTEM
1 lC
(p/n D-11883 - Game Number)
System 11 C eliminates the sound
circuit entirely. (All audio pro-
cessing occurs on the Audio Board
now.)