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My garage door opener (Craftsman 1/2 HP) stopped working some time ago (even lights didn't come on). I replaced the circuit board and now the lights are working and the board reacts to the remote (rapid blinking) but the motor doesn't start (doesn't even make a noise). I decided to replace the motor but it didn't help. There is a large capacitor between the CB and the motor. When I press the remote my voltage meter doesn't show anything on that capacitor's legs. Could it be the capacitor?

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When I was working on modifying my garage door opener, I found two things:

  1. One of the failure sensors was tripped; there are several, but the one that got me was the obstruction sensor. It was incredibly easy to bypass by short-circuiting the sensor's connection with a jumper wire.

  2. The communication may be off, especially since you replaced the board and remotes sometimes don't clear their memory so well; check the blink patterns in the diagnosis manual. The blinks may indicate that the remote's rolling keycode pattern is incorrect. This is exactly what happened to me.

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No voltage at the capacitor may mean it is never getting current to be charged. There is some sort of relay that the computer triggers to run the motor. That is a likely failure point in the system.

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Well, that relay is probably a part of circuit board that I recently replaced. I also replaced the RPM sensor. Still for some reason the motor doesn't start... – kirill_l Jul 14 '12 at 13:24
did you check that the relay is in-fact changing state? either from normally open or normally closed circuit. then you can eliminate your remote and board... A picture of the board and wires would help. – Hightower Oct 9 '12 at 9:33

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