Supersonic (Bally, 1979): faults and replacement boards (Bally MPU)

June 26, 2026

Does your Bally Supersonic no longer start, have its displays off, no sound or runaway coils? These symptoms are typical of Bally microprocessor pinball machines, whose original MPU board is now over 40 years old and almost always suffers from a battery that has leaked. Good news: the BallyFA replacement MPU board, Plug & Play and battery-free, brings your machine back to life.

Supersonic (Bally, 1979): overview

Released in early 1979 on a supersonic aviation theme, Supersonic is a great Bally solid state hit (more than 10,000 units). It introduces the Bally electronic sound board (AS-2818-32), which replaces the chimes. It uses the Bally MPU from the AS-2518 series.

Manufacturer: Bally
Year: 1979
Electronic system: Bally MPU (AS-2518)
Type: electronic pinball (solid state)
Theme: supersonic aviation

Bally MPU board (BallyFA) — Supersonic — The MPU board controls the entire Bally pinball machine.

Common faults (Bally / Stern)

On Bally and Stern microprocessor machines (1977-1985), 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, impossible start-up), 5101 RAM and sockets to replace, MPU/power connectors oxidised or burnt (look for heat marks), displays with missing segments, and a power/driver board (rectifier, fuses, coil transistors) to rework.

Issues specific to Supersonic (forum feedback)

No sound: the electronic sound board AS-2818-32 (first generation) is diagnosed separately.
Leaked battery on the MPU: corrosion around U10/U11.
Displays off or partial: the displays' power supply and MPU to check.
Runaway or dead coils: driver board (transistors, fuses) to rework.
Oxidised or burnt connectors: to replace (repin) to make the machine reliable.
Blowing fuses: look for a shorted rectifier or coil.

Checking a Bally board with a multimeter — Supersonic — The multimeter: essential for checking the power supply and diagnosing the MPU.

Replacement boards compatible with Supersonic

BallyFA — replacement MPU board (battery-free).
BallyDri — power supply + driver.
BallyLa_60 — lamp driver.

BallyDri power and driver board for Bally — Supersonic — The BallyDri: replacement power and driver board, Plug & Play installation.

📚 Further reading: Guide: which MPU board for a Bally / Stern (1977-1985)?

The BallyFA replaces the original MPU board (start-up, logic, battery-free memory) and does away with the battery, the no.1 cause of corrosion. For the coils and the power supply, the BallyDri takes over; the lamps via the BallyLa_60. The sound board is serviced separately. Plug & Play installation, battery-free, free support. Contact us.

FAQ — Supersonic Bally

My Supersonic no longer starts.
Check the battery and the corrosion around U10/U11. The BallyFA replaces the MPU and works without a battery.

I have no sound any more.
The electronic sound board is diagnosed separately; the BallyFA makes the MPU and the game logic reliable.

Is the BallyFA compatible with my Bally?
Yes, for Bally/Stern microprocessor machines (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 trace on the MPU board of your Supersonic; remove the original battery if it is still present.
Power supply: measure the voltages (especially 5 V) and check they reach the MPU; check the rectifier and the fuses on the power board.
MPU components: check the 6821 PIAs (U10/U11) and the 5101 RAM, often oxidised by the battery.
Connectors: repin the oxidised or burnt connectors, especially between the MPU and the power supply.
Displays: check the displays' power supply; test with a known-good display.
Final test: check start-up, credits, coils and displays; the BallyFA replaces the MPU without a battery; if needed, contact free support.