All the six-digit score displays are dark while the four-digit status display works.

Score displays are off but the status display works

Cause: Missing 5 V AC filament supply, missing +8 V DC offset, missing +60 V DC, or an overload or shorted zener on the +42 V output dragging the 60 V down.

Checks

• Measure about 5 V AC at the score displays (filament supply).
• Measure +8 V DC at the power supply output and at the center tap of the bottom board transformer winding.
• Measure +60 V DC at the power supply output.

Fix

• Restore the missing supply; if 60 V is low, look for excess load or a shorted zener on the 42 V output.

The display supply carries 60 V DC (and 42 V DC); keep fingers off the power supply and display boards while the game is on.

Systems

• Gottlieb System 80

Related tips

• Seven-digit display board (A14) parts
• A display segment or digit is always on or always off
• Telling a bad display driver from a bad display tube
• The display voltages to check
• How the Gottlieb fluorescent displays work
• Measuring voltages on a display board
• Meter check of the display board 7432
• Checking the +60 V filter caps on a display board

Source: System 80 Service Manual, Gottlieb