Wild Fyre (Stern, 1978): faults and replacement board (Stern M-100 MPU)
Is your Stern Wild Fyre no longer starting, showing dead displays, blowing the playfield fuse or stuck with inert coils? These symptoms are typical of Stern microprocessor pinballs (M-100 MPU): the original board is now over 45 years old and almost always suffers from a leaked battery. A battery-free replacement board gives the machine a second life.
About the Wild Fyre (Stern, 1978)
Released in October 1978, Wild Fyre is a solid-state pinball from Stern Electronics designed by Harry Williams, with about 2,400 units produced. It uses the Stern M-100 MPU board and the SB-100 sound board.
- Manufacturer: Stern Electronics
- Year: 1978
- Electronic system: Stern M-100 MPU (+ SB-100 sound board)
- Type: solid-state (electronic) pinball
- Theme: fantasy / fire
Common faults (Stern M-100)
On Stern M-100 machines (1977-1979), the recurring faults come from ageing: battery leaking on the MPU (trace corrosion around U10/U11, the number-one cause of dead boards), tired logic circuits (5101 RAM, 6821 PIA, no start-up), oxidised or burnt Molex connectors between the MPU and power supply, displays with missing segments, and a power/driver board to overhaul (bridge rectifier, fuses, coil transistors).
Wild Fyre-specific issues (forum feedback)
- Score displays dead while the rest of the game works: display power supply and MPU link to check.
- The game enters attract mode but refuses to start a game, the coin lockout coil not releasing.
- Playfield fuse blows as soon as the coils activate (bumpers, outhole, slingshots): a shorted driver transistor to look for.
- The machine only boots with the sound board unplugged: the SB-100 loads the power supply and blocks MPU start-up.
- Saucers (ejectors) that no longer kick the ball out after 3 to 10 minutes of play, working again after cooling down, despite 45 V present at the coil.
- Playfield lamps dead in groups and corroded Molex connectors to re-pin.
Replacement boards compatible with Wild Fyre
Important: Wild Fyre uses a Stern M-100 MPU, close to but distinct from the Bally boards. Confirm the right board before ordering: contact us with the references of your boards.
- BallyFA — battery-free MPU.
- BallyDri — power supply + driver.
- BallyLa_60 — lamp driver.
Plug & Play installation, battery-free, free support.
FAQ — Wild Fyre Stern
Which replacement board for my Wild Fyre?
Wild Fyre is fitted with a Stern M-100 MPU: contact us with the references of your boards, and we will confirm the right solution (battery-free).
My Wild Fyre only starts if I unplug the sound board.
This is a classic: the SB-100 loads the power supply. Diagnose the sound board separately before concluding that the MPU is dead.
Why does the playfield fuse blow as soon as a coil activates?
A shorted driver transistor powers the coil permanently. Check the driver-board transistors before fitting a new fuse.
Should I keep the original battery?
No: a battery-free board removes the number-one cause of corrosion.
Does a battery-free board keep the settings and high scores?
Yes: non-volatile memory keeps settings and scores when powered off, with no battery and no corrosion.
What is the warranty?
6-month warranty (parts and labour) against any fault not caused by misuse + 30-day money-back guarantee. Free technical support.
Useful guides
- How much does pinball repair cost? The price guide
- How much is my pinball worth? Rating and valuation
- Pinball leg sizes: the complete guide
- Which MPU board for a Bally/Stern?
