Evel Knievel (Bally, 1977): common faults and replacement boards (Bally MPU)
Does your Bally Evel Knievel light up but do nothing, reset, have stuck coils or a dead flipper? 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.
Evel Knievel (Bally, 1977): overview
Released in 1977, Evel Knievel is one of Bally's very first solid-state pinball machines, themed around the famous motorcycle stuntman. It exists in electromechanical and solid-state versions; this article covers the microprocessor version.
- Manufacturer: Bally
- Year: 1977
- Electronic system: Bally MPU (solid-state)
- Type: solid-state pinball
- Theme: motorcycle stuntman / Evel Knievel
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 Evel Knievel (forum feedback)
- Lights up but won't boot: often a failed 6821 PIA (U10) or battery corrosion; diagnose with a PIA tester.
- Solenoids and resets: coil and reset problems linked to the driver board.
- Cracked solder joints on the driver board: to rework; wires pulled out of their female connector to re-crimp.
- A dead flipper / silent chimes: to check (coil, switch, sound driver).
- Leaked battery on the MPU: corrosion around U10/U11.
- Oxidised connectors: to replace for a reliable machine.
Replacement boards compatible with Evel Knievel
- 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, as well as the dependence on tired PIAs. 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 — Evel Knievel Bally
My Evel Knievel lights up but won't boot.
Often a 6821 PIA (U10) or battery corrosion. The BallyFA replaces the MPU and its PIAs, and works without a battery.
Coils stay stuck or the machine resets.
On the power side, the driver board is to blame: the BallyDri (power + driver) replaces it.
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 Evel Knievel 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.
