Sega/Stern White Star Repair
 |
Click to go back to the Data East/Sega/Stern pinball repair guides index.
1 Introduction
2 Games
2.1 Sega
- Apollo 13
- Goldeneye
- Twister
- Independence Day
- Space Jam
- Star Wars Trilogy
- The Lost World Jurassic Park
- The X Files
- Starship Troopers
- Viper Night Driving
- Lost in Space
- Godzilla
- Harley-Davidson
- South Park
2.2 Stern
- Striker Xtreme
- Sharkey's Shootout
- High Roller Casino
- Austin Powers
- Monopoly
- NFL
- Playboy
- Roller Coaster Tycoon
- The Simpsons Pinball Party
- Terminator 3: Rise Of The Machines
- The Lord Of The Rings
- Ripley's Believe It Or Not
- Elvis
- Grand Prix
- The Sopranos
- NASCAR
3 Technical Info
3.1 The White Star Board Set
3.1.1 CPU / Sound Board
3.1.2 Power Driver Board
3.1.3 Display Controller Board
3.1.4 Display Power Supply
3.1.5 128 x 32 Dot Matrix Display
All Sega or Stern White Star games make use of a 128 x 32 "standard" dot matrix display.
3.2 Recommended Documentation
As always, it is highly recommended to possess a game manual. Every game manual is full of detailed information regarding game specific switch, lamp, and coil assignments. Equally, details for maneuvering through test, audit, and bookkeeping screen menus, schematics for all boards used, and game specific mechanical assemblies are included. Hard copy game manuals can be purchased through several of recommended pinball parts suppliers.
The Stern Pinball, Inc. website currently archives theory of operation and board schematics in PDF form at the time of this writing. Scroll down to the bottom of the linked page to review the documents available.
3.3 Switch Matrix
3.4 Dedicated Switches
3.5 Lamp Matrix
3.6 Trough Opto Boards
3.7 Flippers
4 Problems and Solutions
4.1 Power Problems
4.2 MPU boot issues
4.2.1 Relocating the battery from the MPU board
4.2.2 Repairing Alkaline Corrosion
Sega/Stern White Star boards are well known for issues with leaky batteries. This is because the Batteries are mounted on the top of the board - with plenty of board beneath it for the corrosion to affect.
Remember - Battery Acid is an Alkali - it needs to be neutralised before fixing any damage that was caused. Most commonly used is vinegar, since it is an acid, however not a strong one and one that will adversely affect the surrounding areas of the board.
4.2.3 Connecting a logic probe to the MPU
4.2.4 Using a PC Power Supply For Bench Testing
4.3 Low +5VDC and Game Resets
The +5VDC for logic power is sourced from the 8VAC secondary windings on the transformer. The 8VAC is fed to the I/O Power Driver Board, and rectified via bridge rectifier, BRDG21. The rectified DC voltage is regulated via an LM338K adjustable voltage regulator. Logic voltage can be adjusted via R116 on the driver board, which is a 50 ohm adjustment potentiometer.
U413, which is located on the CPU / sound board next to the reset button, is a Dallas Maxim DS1232 monitoring chip. In theory, should the logic voltage dip to less than 5% or +4.75VDC, the DS1232 will force a reset of the CPU. However, it has been determined that most White Star board sets will not function properly below +4.85VDC.
If the voltage on the power I/O driver board is below the +4.85VDC threshold, adjustment can be made via the R116 adjustment pot, until a satisfactory voltage is achieved. The best location to measure the +5VDC is at the bottom leg of resistor R114. R114 is located in the vicinity of the R116 adjustment pot, and just below the +5VDC LED, L2. If a satisfactory voltage cannot be achieved, turn the game off. Remove connector J16, located above the LM338 regulator. Turn the game back on, and measure the +5V again. If a satisfactory voltage can be acquired with J16 disconnected, a board or component which uses the +5VDC is "dragging" it down. Turn the game off, and remove all 5V input connectors on all other boards at this time. Reconnect J16 again, and review the logic voltage on the I/O Power Driver board. Repeat the process of turning off the game, and reinstalling logic power connectors one at a time to determine the suspect board. Keep in mind that all opto switch receivers used throughout the game use the same +5VDC logic lines. If no other boards in the backbox appear to be suspect, an opto receiver board may be at fault.
Should the game start randomly resetting, the first course of action is to measure the +5VDC on the I/O Power Driver Board. If the logic voltage is within spec., measure the +5VDC on the CPU / sound board. Unfortunately, there are no definitive +5V test points on the CPU / sound board. The best location to measure the +5V is at pin 8 of U413. If the voltage drastically differs between the measurement of the I/O Power Driver Board and pin 8 of U413, turn the game off. Remove and reseat connections CN2 on the CPU / sound board and J16 on the I/O power driver board.
4.4 Solenoid problems
4.5 Lamp problems
4.6 Switch problems
4.7 Display problems
4.8 Sound problems
4.9 Flipper problems
4.10 Pop bumper problems
5 Game Specific Problems and Fixes
Example would be servo controller on Independence Day pinball
Lord Of The Rings -
Balrog. If your Balrog stops registering hits. A little checking will sort it out. It is a micro mini switch with a roller on it. May need adjusting. Known problems past that are flaky or bad switch. And wiring. The Balrog moves so wires can break inside where you can't see them. Easy to check the switch and wires with a meter. And the wires push into an IDC connector nearby, be sure they are pushed in tight. LTG :)
6 Repair Logs
Did you do a repair? Log it here as a possible solution for others.