After vacuuming inside the cabinet, only a couple of coils fire in ball search; others fire only when grounded by hand. Later the display stays dark and the CPU board LEDs are off, though GI works.

After cleaning the cabinet most coils are dead and the display goes dark: reseat J16

Cause: Connector J16 on the I/O power driver board, which sends 5 V and 12 V to the other boards, had been disturbed and was not making good contact.

Checks

• Check the LEDs on the I/O board and measure 5 V at the CPU board.
• Reseat every connector, and press the J16 housing firmly onto its header; watch whether the display comes on.
• Inspect the insulation-displacement connectors for wires that have pulled out of their contacts.

Fix

• Reseat J16, and replace the connector if it is loose or damaged.

Systems

• Sega/Stern Whitestar

Games

• The Sopranos

Related tips

• Won't boot after a board swap, CPU LEDs dark: loose 5 V wire in the CPU power plug
• Whitestar: I/O board blanking LED flashes, lamp rows 1 and 3 dead: data bus short
• Game keeps resetting with blank display and blinking lamps: faulty 6264 RAM
• One flipper flips but has a weak hold and drops when hit: bad transistor at Q16
• F7 blows at power-up: flasher socket tabs touching, which also shorted Q27
• Resets when the flippers are used: arcing flipper coil, then bridge rectifier BR21
• Whitestar flipper weak or dead after a MOSFET swap: fake part, test with TPL1
• Left slingshot, some lamps and a trough switch dead: wires torn by the playfield slide

Source: Pinball Repair help group!! (Facebook group)