NES blinking red light / grey screen fix (72-pin connector and CIC lockout chip)
A front-loading NES that flashes its power light and the screen about once a second is failing the lockout check, almost always because the cartridge and the 72-pin connector aren't making a clean contact. Clean the games first, then clean, refresh or replace the 72-pin connector; disabling the 10NES lockout chip is an optional extra, not a cure.
Written by the CircuitScope research team in our own words, from the sources listed at the end, and checked by our moderators.
A front-loading NES that flashes its power light and the screen about once a second is failing the lockout check, almost always because the cartridge and the 72-pin connector aren't making a clean contact. Clean the games first, then clean, refresh or replace the 72-pin connector; disabling the 10NES lockout chip is an optional extra, not a cure.
Difficulty: Easy · Time: about 60 minutes
Related codes / lights: Power LED and screen blink at about 1 Hz (lockout check failing), Solid grey or white screen (no valid data from the cartridge; also what you see with the lockout chip disabled and a bad contact)
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