Rebuild the high-voltage display supply

Steps

• Unplug the game, remove the power supply board and let the high-voltage caps discharge.
• Replace C6 and C7 (.01 mfd 500 V) and C2 (160 mfd 250 V; 220 mfd 250 V is fine).
• Replace R5 (22k 1/2 W) and trim pot VR1 (25k).
• Replace Q1 (2N3584 / NTE384) and Q2, Q3 (2N3440 / NTE396).
• Replace D10 (1N5275A) and D5-D8 (1N4004).
• Refit the board, power up and set TP2 with VR1.

The display supply runs at 170-230 volts DC; touch nothing on the high-voltage section with the game on, and let it discharge before working on it.

Systems

• Bally 6803

Related tips

• Replace high-voltage caps C6 and C7 before they take out Q2/Q3
• High-voltage input fuse FU2 blows
• Display high voltage above 190 V and VR1 cannot lower it
• Power supply test points and their voltages
• Check every power supply fuse before first power-up
• Power supply test point ranges
• 6803 power supply fuse ratings
• Strange intermittent faults from power supply solder joints

Source: Repairing Bally 6803 Pinball Games from 1985 to 1989, Clay Harrell (pinrepair.com)