Eight Ball (Bally, 1977): common faults and replacement boards (Bally MPU)
Does your Bally Eight Ball fail to boot, have dead displays, targets that no longer reset or dead lamps? These symptoms are typical of microprocessor Bally pinball machines, whose original MPU board is now over 40 years old and almost always suffers from a leaked battery. The good news: the BallyFA replacement MPU board, Plug & Play and battery-free, brings your machine back to life.
Eight Ball (Bally, 1977): overview
Released in 1977 on an American pool theme (8-ball), Eight Ball is one of Bally's biggest solid-state hits, produced in huge numbers. It uses the famous Bally AS-2518-17 MPU.
- Manufacturer: Bally
- Year: 1977
- Electronic system: Bally MPU (AS-2518-17)
- Type: solid-state pinball
- Theme: billiards / 8-ball
Common faults (Bally / Stern)
On microprocessor Bally and Stern games (1977-1985), the recurring faults come from ageing: leaking battery on the MPU (corrosion of traces and sockets around U10/U11, the No. 1 cause of dead boards), tired 6821 PIAs (U10/U11) (oxidised legs, no boot), 5101 RAM and sockets to replace, MPU/power connectors oxidised or burnt (look for heat marks), displays with missing segments, and the power/driver board (rectifier, fuses, coil transistors) to rework.
Issues specific to Eight Ball (forum feedback)
- Connectors to replace: the MPU's J4 connector deteriorates (pins hanging by a few strands); without rework, the machine stays unreliable.
- Drop targets that won't reset: often the outhole switch no longer registers.
- Dead feature lamps: the common 6 V bus must be present; check the rectifier-board connector (burnt pins).
- Fuses to check: 3/16 A on the driver board (AS-2518-22) and 3/4 A on the rectifier board.
- Leaked battery on the MPU: corrosion around U10/U11.
- Recommended repair order: rectifier, then driver board, then MPU, then lamp board.
Replacement boards compatible with Eight Ball
- BallyFA — replacement MPU board (battery-free).
- BallyDri — power supply + driver.
- BallyLa_60 — lamp driver.
📚 Further reading: Guide: which MPU board for a Bally / Stern (1977-1985)?
The BallyFA replaces the original MPU board (boot-up, logic, battery-free memory) and removes the battery, the No. 1 cause of corrosion. For the coils and power, the BallyDri takes over; the lamps via the BallyLa_60. Plug & Play installation, battery-free, free support. Contact us.
FAQ — Eight Ball Bally
My Eight Ball is unreliable (dropouts, resets).
Often the connectors (MPU J4) to redo. The BallyFA replaces the MPU and makes boot-up reliable, battery-free.
My feature lamps are dead.
Check the 6 V bus and the rectifier-board connector (burnt pins); the BallyLa_60 replaces the lamp driver.
Is the BallyFA compatible with my Bally?
Yes, for microprocessor Bally/Stern games (1977-1985). If in doubt, contact us.
Should I keep the original battery?
No. The BallyFA works without a battery and removes the No. 1 cause of corrosion.
How long does it take to install a replacement board?
Installation is Plug & Play: a few minutes, no soldering, with tutorials and free support.
Does a battery-free board keep the settings and high scores?
Yes. Modern replacement boards use non-volatile memory: no more battery, no more corrosion, and the settings are kept when powered off.
Step-by-step diagnosis
- Power off, visual inspection: look for any battery or corrosion damage on your Eight Ball MPU, especially around U10/U11; remove the battery if still present.
- Power: measure the 5 V and check that it reaches the MPU (rework the power/rectifier board and the fuses if the voltage drops).
- Grounds and connectors: rework the oxidised or burnt MPU/power connectors (heat marks) between the boards.
- MPU components: check the 6821 PIAs (U10/U11) and the 5101 RAM, often tired or corroded by the battery.
- Displays: never plug or unplug a display while powered on; test with a known-good display.
- Final test: check start-up, credits, coils and displays; reminder: the BallyFA replaces the MPU and boots without a battery. If needed, contact our free support.
