Nine Ball (Stern, 1980): faults and replacement boards (Stern M-200 MPU)
Is your Nine Ball by Stern showing an MPU eaten away by the battery, displays that go dark after about thirty seconds, a hum in the speakers or tired drop targets? These symptoms are typical of Stern microprocessor machines (M-200 MPU): the original board is now more than 45 years old and has almost always suffered from a leaking battery. A battery-free replacement board gives the machine a second life.
Nine Ball (Stern, 1980): an introduction
Released in 1980, Nine Ball brings pool to a very open playfield, with its banks of drop targets and its ball locks. It runs on the Stern M-200 MPU board and the SB-300 sound board, both distinct from the Bally boards.
- Manufacturer: Stern Electronics
- Year: 1980
- Electronic system: Stern M-200 MPU, SB-300 sound board
- Type: solid state pinball machine, 7-segment displays
- Theme: pool (nine-ball)
Common faults (Stern M-200 MPU)
On Stern M-200 microprocessor machines (1979-1985), the recurring faults come down to age: a leaking battery on the MPU (corroded traces around the 5101 RAM chips at U8/U13, the number one cause of dead boards), tired RAM and logic chips (no boot, reboots, looping in the tests), oxidised or burnt Molex connectors on the MPU and power supply side (pins to be replaced male and female), displays with missing or flickering segments, the rectifier and solenoid driver board (dried-out capacitors, bridge rectifier, fuses, coil transistors) and a sound board with dried-out capacitors.
Problems specific to the Nine Ball (from the forums)
- An MPU marked by the battery: almost every Nine Ball found today shows traces of leakage; once the corrosion has eaten into the traces, replacement is safer than repair.
- Displays that go dark after about thirty seconds: a component fault reported on the forums, to be looked for on the display power supply side.
- A loud hum after work on the SB-300 sound board: dried-out capacitors to replace (kits are available) and connectors that need re-pinning rather than simply being pushed back on.
- An erratic switch matrix: rows or columns that respond badly, to be isolated in switch test mode before suspecting the MPU.
- Drop targets to rebuild: the mechanisms are the game's mechanical weak point and the parts are hard to find.
- A temperamental left ball lock: a fault documented on the forums, to be dealt with by adjusting the mechanism and its switch.
Replacement boards compatible with the Nine Ball
- BallyFA — battery-free MPU.
- BallyDri — power supply + driver.
- BallyLa_60 — lamp driver.
Plug & Play installation, battery-free, free support.
Worth knowing: the Nine Ball is fitted with a Stern M-200 MPU, whose part numbers differ from the Bally -35 boards. Get in touch with the part numbers of your boards: we confirm the right solution before you buy anything.
FAQ — Nine Ball Stern
Which replacement board for my Nine Ball?
The Nine Ball uses a Stern M-200 MPU: get in touch with the part numbers of your boards and we will confirm the right board (battery-free) before you buy.
My displays go dark after a few seconds.
A known fault on the Nine Ball: check the display power supply and the connectors before suspecting the displays themselves.
The SB-300 sound board hums — what should I do?
Its original capacitors are dried out: recapping the board and re-pinning the connectors settles the majority of cases.
Should I keep the original battery?
No: a battery-free board removes the number one cause of corrosion.
What warranty comes with boards from Pinballs Store?
A 6-month warranty (parts and labour) against any fault not caused by misuse, plus 30 days money back. Technical support is free.
Does a battery-free board keep the settings and high scores?
Yes. Modern replacement boards use non-volatile memory: no battery, no corrosion, and the settings are kept when the machine is switched off.
Useful guides
- How much does pinball machine repair cost? The price guide
- How much is my pinball machine worth? Values and estimates
- Pinball machine leg sizes: the guide by machine
- Which MPU board for a Bally/Stern?
See also
Sources & further reading
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