Galaxy (Stern, 1980): faults and replacement boards (Stern M-200 MPU)
Is your Galaxy by Stern looping on the MPU check, stuck in tilt, showing a flickering display or producing weak, distorted sound? 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.
Galaxy (Stern, 1980): an introduction
Released in 1980, Galaxy is the second-biggest production run of the "Classic Stern" era after Meteor, with roughly 5,000 units built. It runs on the Stern M-200 MPU board, which is distinct from the Bally boards.
- Manufacturer: Stern Electronics
- Year: 1980
- Electronic system: Stern M-200 MPU
- Type: solid state pinball machine, 7-segment displays
- Theme: space, science fiction
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 Galaxy (from the forums)
- Battery corrosion reaching connector J3: the electrolyte migrates as far as the male pins and creates short circuits; the connector has to be desoldered, the area decontaminated, and a new one soldered in.
- Tilt code showing permanently: isolate the cause by removing J3 in switch test mode, to decide between shorted cabinet wiring and a fault on the MPU.
- Looping on the MPU check ("continuous MPU check"): a fault documented on the forums, to be looked for on the RAM and the 5 V supply.
- Weak or distorted sound: dried-out capacitors on the sound board, and connectors that need re-pinning.
- Player 1 display flickering: cold solder joints; missing digits point instead to a broken wire or a broken pin in the MPU harness.
- Tired Molex connectors: replace male and female pins; if unplugging and replugging "fixes" the fault, the connector is dead.
Replacement boards compatible with the Galaxy
- BallyFA — battery-free MPU.
- BallyDri — power supply + driver.
- BallyLa_60 — lamp driver.
Plug & Play installation, battery-free, free support.
Worth knowing: the Galaxy 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 — Galaxy Stern
Which replacement board for my Galaxy?
The Galaxy 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 Galaxy stays in tilt permanently.
Remove connector J3 in switch test mode: if the tilt clears, the fault is in the cabinet wiring; if not, the MPU is to blame (often battery corrosion that has reached J3).
The machine loops on the MPU check at start-up.
Check the RAM and the 5 V supply, after dealing with any trace of battery corrosion.
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
- Pinball machine leg sizes: the guide by machine
- Which MPU board for a Bally/Stern?
See also
Sources & further reading
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