The four-digit credit/ball-in-play display is dark while the score displays are fine.

Status display is off but the score displays work

Cause: Missing 3 V AC filament supply, missing +42 V DC, missing +5 V DC offset at the transformer center tap, wrong control board option switches 18 and 28, or a faulty status display.

Checks

• Measure about 3 V AC at the status display.
• Measure +42 V DC at the power supply output.
• Measure the +5 V DC offset at the center tap of the bottom board transformer winding.
• Check control board option switches 18 and 28.

Fix

• Correct the supply or switch setting; otherwise replace the status display.

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

• All displays are dark
• A display segment or digit is always on or always off
• How the control board drives the displays
• Display data in attract mode
• Scores light at once and the status display stays dark
• How the four-digit status display shows a "1"
• Six-digit and four-digit display voltages
• Control board display connectors A1-J2 and A1-J3

Source: System 80 Service Manual, Gottlieb