The ball trough proximity switch (switch 26) misreads or stops working.
Twilight Zone trough proximity sensor (switch 26) problems
Cause: The Twilight Zone sensor has no adjustment pot and does not self-adjust. Usual causes are the sensor board sitting too far from the ball, worn 2-pin .100 inch Molex connector pins on the driver board, cracked solder on the driver board header pins, or a failed TDA0161 chip.
Checks
- The assembly has a sensor board plus a separate driver board; the driver is the one fitted with two Molex plugs.
- Reseating the 2-pin connector fixing it for a while points to worn crimp pins.
Fix
- Move the sensor board closer to the ball.
- Replace the .100 inch crimp pins in the housing, or solder the wires to the header pins.
- Reflow the driver board header pins.
- Replace the TDA0161 chip (Williams 5370-13452-00), or the whole proximity driver board.
Systems
Games
Related tips
- Twilight Zone: "clock is broken" error
- Twilight Zone: LED lighting mod for the clock
- Twilight Zone clock uses eight sensitive U optos
- Twilight Zone: diode mod to cool the clock with stock bulbs
- Twilight Zone ninth switch column (clock switches)
- Eddy sensors: electronic ball switches under the playfield
- Test report lists switches the game doesn't have
- Ninth switch column on Twilight Zone, Indiana Jones and STNG
Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Three, Clay Harrell (pinrepair.com)