Garage Door Opener problem

[meintv]

Hi, This is about a Craftsman chain drive garage door opener made in 1996. It stopped working a few days ago, and after disassembling it, it was obvious that the gear and sprocket needed to be replaced. I did replace those parts, but after putting everything back under the ceiling again, the door won't move much anymore. The chain moves a few inches in one direction, then reverses, moves a few inches in the other direction and then stops. This occurs independent of whether the door is locked into the chain, or whether the chain moves without the door. Of course, I had to loosen the chain during the installation, so does this sound like I tightened it too much (or not enough?) when reinstalling it? Or could this be a safety "auto reverse" issue? But would that also explain what happens when the door is disconnected? Are the three wires that go into in the back of the unit part of the auto reverse process? Most importantly, I would of course like to find out how to solve the problem, so any suggestion would very much be appreciated. Thanks, Tim.

[Bob F]

It is probably a matter of the position of the sprocket on the chain, which affect the limit switch operation. Or, adjustment issues on the limit switches or misassembly of the gear/sprocket in relation to the limit switches.

Bob

[tnom]

Did you rotate any of the remaining parts that would appreciably change the limit setting?. Is the door in the same position after repairs were completed?

It sounds like the bearing on top for the sprocket may be worn out Did the sprocket actually wear out? Usually the recommended tension on the chain will destroy the bearing on top before the sprocket.

The three wires on bottom are for up and down limits. Brown-closest to shaft, gray-middle wire and yellow-farthest from shaft. Why do you ask about wires? Did you disturb other wiring?

[doordoc]

It sounds like you left the revolution counter cup (black plastic w/ notches in the side) off or it isn't seated properly on the end of the motor shaft. This is part of the reversing system & is like a timing circuit. The board on the end of the motor sends pulses thru the notches & when the timing of the pulses change (motor slows down) the door reverses. When this part isn't working properly the door will move exactly 4" in either direction.

DoorDoc www.DoorsAnd> Hi,

[meintv]

Wow, I am impressed.....I have to admit that I am guilty as charged. I did not put the RCC back on......When I reassembled the machine after changing the gear/sprocket, I must have rotated the gear 120 deg. from its original position, so now the openings for the RCC were out of place, and it wouldn't fit. In my naivety, I just ignored this, figuring that a piece of plastic wouldn't matter that much. Was I wrong..... Anyway, thank you so much! I really appreciate your help (and of course, everybody else's ideas), and I will try to fix this then. Cheers, Tim.