On one score display several digits look blotchy, patchy or faint (sometimes called measles) while the others are normal; some displays like this improve after warming up for a few minutes.
Classic Stern display: blotchy, faint digits on one display: outgassed glass
Cause: The gas-discharge display glass has outgassed. That cannot be repaired on the board.
Checks
- Swap the display with a good one to see whether the fault follows the display.
- Repin the display connector and reflow the header pins first if only a digit or two is affected, since bad contacts can look similar.
Fix
- Replace the display glass or the whole display, or fit an LED replacement display.
These displays run on high voltage (around 190 V DC): switch off and let the supply discharge before handling them.
Systems
Related tips
- Display glass dim, digits missing or slow to light
- Replace a score display glass
- Bally and Stern score display boards
- One digit missing on a score display
- Score display digit parts by position
- Score displays dim
- One or two score displays completely blank
- All displays show strange scores (one bad decoder)
Source: Pinball Repair help group!! (Facebook group)