LED and incandescent lamps flicker or strobe across the game, although voltages, wiring, the rectifier bridge and even a replacement lamp board all check out.

All lamps strobe after a replacement CPU board was fitted: check its M-200 jumpers

Cause: An aftermarket replacement CPU board had been fitted without moving its jumpers to the M-200 setting this game needs, so the board's timing was wrong for the lamp circuits.

Checks

• If a replacement CPU board has been installed, look up its jumper chart and confirm it is set for an M-200 game, not M-100.

Fix

• Set the replacement board's jumpers for M-200 (power off), then power up and check the lamps.

Systems

• Stern MPU-200

Games

• Split Second

Related tips

• MPU LED gives only two flashes at power-up: replace the 5101 RAM chips
• Leave the ROM jumpers alone until the LED flickers
• Flicker but no first flash
• Fit the replacement MPU LED the right way round
• Stern M-200 MPU jumper settings by ROM set
• M-200 clock-speed jumpers E32-E33 and E34-E35
• Reseating socketed chips

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