Midway Off Road Thunder Operation Manual

							Wiring & Circuit Information          4-21
Wheel Driver Board Schematic, 3/8 
						

							Wiring & Circuit Information          4-22
Wheel Driver Board Schematic, 4/8 
						

							Wiring & Circuit Information          4-23
Wheel Driver Board Schematic, 5/8 
						

							Wiring & Circuit Information          4-24
Wheel Driver Board Schematic, 6/8 
						

							Wiring & Circuit Information          4-25
Wheel Driver Board Schematic, 7/8 
						

							Wiring & Circuit Information          4-26
Wheel Driver Board Schematic, 8/8 
						

							Servicing          5-1
O
OO OFFROAD
FFROADFFROAD FFROAD
THUNDER
THUNDERTHUNDER THUNDER 
    TM
CHAPTER
5
SERVICING
NOTICE: 
The term VGM refers to the video game machine.
NOTICE: 
Avoid damage to electronics! Turn off VGM power before servicing circuit
boards or any electronic assembly. Never “hot plug” circuit boards.
CAUTION:
 Static electricity builds up on your body. This static can damage or destroy
sensitive circuits. Before touching or handling electronics, discharge static electricity by
touching the power supply chassis. 
						

							Servicing          5-2
DISASSEMBLY & REASSEMBLY
This chapter includes summarized procedures for disassembling and reassembling VGM components.
Only qualified service personnel should repair VGM equipment. The following product guidelines apply to
all video game operators and service personnel. Notes, cautions and warnings appear throughout this
manual where they apply. Study the Safety pages before beginning service.
• 
Arcade Computer
Switch off power to the VGM.
Open and remove the rear door.
The Arcade Computer is behind
this door. To expose Arcade
Computer circuitry, loosen four
metal thumbscrews. Don’t remove
the screws. These screws reside
at the top and bottom corners of
the case. Slide off the back of the
computer.
• Audio Amplifier Board BB12
Switch off power to the VGM. Unlock and open the rear door. The BB12 Audio Amplifier Board
mounts to the wooden shelf behind the steering motor. Note the orientation of the connector and
other cables. Extract the harnesses from the board connectors. Remove mounting screws from the
Audio Board. Lift the board out of the cabinet. Handle the board by a heatsink. If you aren’t
reinstalling the board, store it in an anti-static bag and protective container.
 
 
• Battery
CAUTION: 
If you install the battery incorrectly, it may explode! Avoid direct shorts
across the terminals or from terminals to ground. These batteries are designed for
very long life. Don’t attempt to recharge these batteries!
CAUTION: 
Avoid an explosion! 
Replacement batteries must match the originals in
size, voltage rating, and composition. Manufacturer recommended equivalent types
are acceptable. Store batteries in a safe place until you’ve completed repairs.
Dispose of used batteries according to manufacturer instructions.
A battery on the CPU Board retains data in memory during power disruptions. This battery is a 3-volt,
lithium button cell. Switch off power to the VGM. Unlock and remove the rear door. Remove the back
of the Arcade Computer. The battery resides toward the edge of the motherboard, near the daughter 
						

							Servicing          5-3 board sockets. Carefully pry up the battery retaining lever. Then grasp the battery edges and remove
the device. Set the battery aside.
Note the “+” marking on one side of the replacement battery. W hen you install a battery, this “+”
marking must face the battery retaining lever. After replacing the battery, set the system clock to the
correct date and time. Also enter the Menu System and check or update system adjustments as
necessary.
• 
Coin Counter
Meter replacement requires vault removal. Switch off power to the VGM. Unlock and open the coin
door and cashbox door. Find the meter behind the bottom of the cashbox door. Remove the cashbox.
Remove two mounting screws at the bottom (front) of the vault assembly. Reach through the cash
door. You’ll find two mounting screws at the back of the vault. Remove these. Access the four
remaining vault screws from the inside-back of the cabinet. Remove these four screws. Slide the vault
out of the cabinet.
Locate the meter wires under the vault. Disconnect wiring at the connector. Remove two mounting
screws from the front of the meter. Remove the meter. Assure that the replacement meter has a
diode across its terminals. This diode protects driver circuits from the meter’s inductive kick. Install
the new meter. Log the new meter count.
• 
Coin Mechanism
Switch off power to the VGM. Unlock the coin door and swing it open. To clean or replace a coin
mechanism, unlatch and remove it. After reinstallation, assure that the mechanism seats fully in its
bracket. Close and lock the release latch. Then close the door. Enter the Menu System to change the
coin mechanism setup. Test known good and bad coins to verify operation.
• 
CPU Board
The CPU Board is part of the
Arcade Computer. Switch off
power to the VGM. Open and
remove the rear door. The Arcade
Computer is behind this door. Find
the four metal thumbscrews at the
top and bottom corners of the
computer case. To expose the
CPU Board, loosen, but don’t
remove these screws. Slide off the
back of the computer. Unscrew
and remove the circuit board
retention bars. Disconnect
external cables to the Video
Board, Network Board and Power
Filter Board. Remove the Video
Board, Network Board and Power
Filter Board. Disconnect the floppy
disk power and data cables at the
disk drive. Remove the floppy
drive-mounting bracket. Lift the
bracket and floppy drive out of the
cabinet. Set these aside for
reassembly.  
						

							Servicing          5-4   Remove the CPU Board power cables at the CPU Board. Remove the circuit board retention bars.
Disconnect the hard drive power and data cables at the disk drive. Remove CPU Board mounting
screws. Lift the circuit board out of the cabinet. Use anti-static packaging from new parts to store
boards that you won’t reinstall.
• 
Dashboard and Steering Mechanism
Switch off power to the VGM. Unlock and
remove the rear door. From inside the
cabinet, disconnect the dash cables. Sit in the
driver’s seat and support the steering wheel.
Remove the top two dashboard mounting
screws. Remove the dash bracket. Slide the
viewing glass upward. Lift the glass out of the
cabinet. Remove the bottom two dash
screws. Remove the dashboard and set it on
your workbench.
Inspect the motor, pulleys, and belt. If the belt
is broken or shows signs of wear, replace it.
Locate the two nuts on each side of the motor
mounting bracket. Loosen all four bracket
nuts. Rotate the tension adjustment bolt as
necessary. Tighten this bolt until the belt is
taut. Then restore correct tension by
loosening the bolt one full turn. Tighten the
motor bracket nuts. 
• DIMMs (Dual In-Line Memory Modules)
DIMM circuits contain the computer read-write
memory for this VGM. Switch off power to the
VGM. Remove the cabinet rear door. Remove
the back of the Arcade Computer. Unplug the
ribbon cable from the floppy drive. Leave the
other end of the cable attached to the CPU
Board. Unscrew and remove the circuit board
retention bars. Remove the floppy drive
mounting bracket. Remove the floppy drive.
Note DIMM positions. Press out on the locking
retainer on each side of the DIMM. The DIMM
should partially or completely pop out of its
socket. Lift the DIMM from its socket. Handle
the DIMM only by its edges.
  To reinstall memory circuits, orient the DIMM
over its socket. Make sure that you’ve
positioned the keying holes and notch properly.
Push the DIMM board into its socket. The
board should snap into place, engaging a
locking retainer at each socket end. Be sure
that the retainers mate tightly with DIMM board
notches. Don’t attempt to force a DIMM into its
socket.
 
CB
A