Joust (Williams, 1983): common faults and System 7 replacement boards

June 26, 2026

Does your Williams Joust fail to boot, reset, see its flippers drop out or have no sound? These symptoms are typical of Williams System 7 pinball machines, whose original boards (MPU, Driver, power supply) are now over 40 years old. The good news: the WillFA7 replacement board, Plug & Play and battery-free, brings your machine back to life.

Joust (Williams, 1983): overview

Released in 1983, Joust is a one-of-a-kind Williams System 7 pinball machine: a head-to-head model where two players face each other across the playfield, each controlling their own flippers, with spinner gates that pass the ball from one side to the other. Inspired by the Joust video game and featuring 4-ball multiball, it had a production run of about 402 units.

Manufacturer: Williams
Year: 1983
Electronic system: Williams System 7
Type: solid-state pinball, head-to-head, 4-ball multiball
Theme: Joust (video game) / medieval jousting

WillFA7 MPU/Driver board for Williams System 3 to 7 — The WillFA7 board replaces the original MPU and Driver of Williams System 3 to 7.

Common faults (System 7)

On Williams System 3 to 7, the recurring faults come from ageing: leaking NiCad battery on the MPU (corrosion, the No. 1 cause of dead boards), worn 40-pin MPU↔Driver connector (the best-known weak point), resets/reboots on a 5 V drop (power headers and connectors to be resoldered), tired power-supply capacitors, displays with missing segments, and a solenoid fuse that blows (slingshot or stuck bumper).

Issues specific to Joust (forum feedback)

Temperamental spinner gates: the switches of the gates between the two sides get dirty and become intermittent.
One side no longer responds: each player controls their own flippers; a dead side points to its switches/coils or the matrix.
4-ball multiball won't start: trough and lock switches to clean or replace.
No boot or resets: corroded battery and worn 40-pin connector, typical of System 7.
No sound: System 7 sound board to be diagnosed.
Displays with missing segments: displays and power supply to rework.

Checking voltages with a multimeter on a Williams System 7 — A multimeter is used to check the 5 V and diagnose the boards of Williams System 7 machines.

Replacement boards compatible with Joust

WillFA7 — 2-in-1 board (MPU + Driver) compatible with System 3 to 7, System 7 included.

WillFA7 replacement board for Williams pinball — The WillFA7: Plug & Play installation, battery-free, with tutorials and free support.

📚 Further reading: Guide: which board for a Williams System 3 to 7?

The WillFA7 replaces the original MPU and Driver board (boot-up, logic resets, coil and multiball driving, battery-free memory) and removes the fragile 40-pin ribbon. The sound board and the mechanical parts (spinner gates, switches) must still be maintained separately; our support team will guide you.

Plug & Play installation, battery-free, free tutorials and support. Contact us.

FAQ — Joust Williams

Only one side of my Joust no longer responds.
Each player has their own flippers and switches; check the switches/coils on the dead side and the matrix. The WillFA7 makes the logic and coil driving reliable.

My Joust won't boot or resets.
A corroded original battery and worn 40-pin connector are the No. 1 causes. The WillFA7 replaces the MPU and Driver and boots without a battery.

Is the WillFA7 compatible with System 7?
Yes. It covers System 3 to 7, System 7 included, and drives the logic, multiball and coils.

Should I keep the original battery?
No. The WillFA7 works without a battery and removes the No. 1 cause of corrosion on System 7.

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

Powered off, visual inspection: look for any battery or corrosion trace on your Joust's MPU; remove the NiCad battery if it is still present.
Power supply: measure the 5 V and check it actually reaches the MPU and Driver (redo the power solder joints and connectors if the voltage drops); check the fuses.
Grounds and power connectors: resolder the tired headers between the boards to eliminate resets and reboots.
40-pin MPU↔Driver connector: re-pin the oxidised link with trifurcon pins, the No. 1 weak point of Williams System 7.
Displays: never plug or unplug a display while powered on; test with a known-good display.
Final test: check boot-up, credits, coils and displays; reminder: the WillFA7 replaces the MPU and Driver and boots without a battery. If needed, contact our free support.