Scope.
This document is a repair guide for Bally electronic pinball games made from 1977 to 1985. Since Stern electronic pinball games use nearly identical electronics, these games are covered too.

This document is three parts (part one is here, and part two is here, and part three is here).

IMPORTANT: Before Starting!
IF YOU HAVE NO EXPERIENCE IN CIRCUIT BOARD REPAIR, YOU SHOULD NOT TRY TO FIX YOUR OWN PINBALL GAME! Before you start any pinball circuit board repair, review the document at http://marvin3m.com/begin, which goes over the basics of circuit board repair. Since these pinball repair documents have been available, repair facilities are reporting a dramatic increase in the number of ruined ("hacked") circuit boards sent in for repair. Most repair facilities will NOT repair your circuit board after it has been unsuccessfully repaired ("hacked").

If you aren't up to repairing pinball circuit boards yourself or need pinball parts or just want to buy a restored game, I recommend seeing the suggested parts & repair sources web page.

Table of Contents

1. Getting Started:
1. Experience, Schematics, Manuals
2. Necessary Tools
3. Parts to have On-Hand
4. Game List
5. Lubrication Notes
6. The Circuit Boards
7. Voltage Test Points on the Boards and the Power Train
8. Fuse Values/Usage & Power Supply Power Distribution

2. Before Turning the Game On:

1. Check the Coil Resistance
2. Removing the MPU Battery and Fixing Corrosion
3. The Power Supply - Blown Fuses, Bridges, etc.
4. Upgrading the Voltage Regulator/Solenoid Driver Board
5. Upgrading the Ground on the MPU Board
6. Pre Power-On Voltage Checks
7. Connectors
8. Setting Free Play

3. When Things Don't Work:

1. Making a MPU test fixture
2. Fixing the MPU (LED flashes and the such)
3. Game ROMs, EPROMs, and Jumper - the Basics
4. -35 MPU Game ROMs, EPROMs, and Jumpers
5. -17 MPU Game ROMs, EPROMs, and Jumpers
6. Stern M-200 MPU Jumpers (using a Stern M-200 in a Bally Game)
7. Converting a -133 MPU (Baby Pacman) to a -35 MPU
8. The Built-In Diagnostics/Bookkeeping
9. Coils: Locked-on, Sporadic, or Not Working (Solenoid Driver board)
10. Lamps: Locked-on or Not Working Feature Lamps (Lamp Driver board)
11. Solenoid Expander Board Problems
12. Auxiliary Lamp Driver Board Problems
13. Switches and the Switch Matrix
14. High Voltage Section Problems (No Score Display Power)
15. Score Display Replacement and Fixes
16. Reset or Lockup Power Problems
17. Sound Board Problems
18. Miscellaneous Problems and Fixes

Bibliography and Credit Where Credit is Due.
Many of the ideas in this repair guide are not original. Lots of people contributed to this document, and I just want to say, "thanks!" Below are a list of the resources used in the development of this guide. Some resources/people may have been innocently left out. If this is the case, and an idea is here that was originally yours, please notify me and I will make sure to give you credit!

• "Electronic Pinball Games Repair Procedures", Bally, part number F.O.560-3, fourth edition, dated October 1, 1981.
• Jerry Clause, who provided tons of tips and tricks.
• Tom Callahan and his web site at www.pin-logic.com.
• Mr. Johnson and his web site at www.aros.net/~rayj/action/tech. Ray's postings and tips were most helpful.
• Duncan Brown. Duncan provided lots of tips and tricks.
• Rob Hayes, who's advice and proof reading were very appreciated.
• David Gersic, who also did proof reading and provided some tips.
• John Robertson and his posts & tips helped mucho grande.
• Dwight Elvey for his posts, tips and tricks.
• A. Reizman for his amazing wealth of knowledge.
• Pinball Liz Tech Reprints #1 to #6, August 1995 to August 1996, for their tips and tricks.

Why is this Document Available?
There has been TONS of information and fixes published for the 1977 to 1985 Bally electronic pinball games. There's no complete information of "here's what to do" in its entirety. This guide should fill that void.