Capacitor C26 holds the display high voltage after power-off
The large C26 filter capacitor in the high-voltage section can stay charged after switch-off and only bleeds down after a few minutes. Shorting it into the logic side of the board can also destroy chips there.
The solenoid driver / regulator board makes about 190 V DC for the score displays (around 230 V on some Stern boards); a shock from it hurts. Work with the game unplugged and let the filter capacitors discharge, and use one hand and insulated probes for live checks.
Systems
Related tips
- Power up and set a rebuilt high-voltage section
- Where the display high voltage enters and leaves the solenoid driver board
- Rebuild the solenoid driver board high-voltage section
- All displays dark after fitting a new power supply: blown solenoid driver board fuse
- High voltage still too high or too low after a rebuild
- No score displays light at all
- The solenoid driver board also carries the 190 V display supply
- First checks before repairing Bally score displays
Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part Three, Clay Harrell (pinrepair.com)