Question about Sears Craftsman LiftMaster Chamberlain Garage Door Opener Wireless Keypad Model 976LM Security+
Lately, my Liftmaster will lose power during opening or closing, resulting in stopping of the garage door going up or down. sometimes the power somes back right away, flickers, or won't come back for a few minutes. Upon reactivation, if I push the button it will either complete is opening/closing or it will lose power again and get interrupted. If I lightly bang on the side of the unit the power will come back on or flicker, like a wire or connection is loose. I've checked all the connections, nothing appears loose or corroded, all looks normal. Could this be the board or RPM sensor?
I had the same problem. Although it appeared to be the logic board, on mine it actually was the connectors between the logic board and the power supply board.
There are 2 connections on the logic board. One white connector with wires going to the main unit, and another set of connectors that plug directly into the smaller circuit board that holds the step-down transformer (120vac - 22vac). These pins were not making good connection between the boards. I simply bent the pins slightly so they would make better contact on the logic board and have not had a problem since. This must be a weak point on these door openers. Purchasing a new logic board would work too, as the connectors are newer and tighter.
Posted on Oct 23, 2008
Mine was also made in 2002, and had the same problem. What I did is put washers under the mounting holes of the transformer/relay board which brings the connector pins on that board up through the logic board. Then, with a soldering iron, I bridged from each soldered pad to each pin to ensure the connnection. BTW, I did this with the ccas in the plastic housing on a work bench.
Posted on Jul 05, 2013
Hmmm...sounds like a common problem as that is exactly what I did. It was very simple to replace the logic board and, voila, I have a fully functioning garage door with an automatic door opener that is healthy again. And, I might add, at probably a third the price of having to replace or have a technician come in and inspect/repair/replace.Thanks for everyone's input!
Posted on Jan 11, 2008
Try a new logic boad
Posted on Jan 10, 2008
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Posted on Jan 02, 2017
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