Question about Sears Craftsman LiftMaster Chamberlain Garage Door Opener Wireless Keypad Model 976LM Security+

4 Answers

Liftmaster garage door intermittent power loss

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?

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  • Anonymous Jan 06, 2008

    I too am having this same exact problem. I have completely removed and reconnected all connections hoping to find a loose connection but to no avail.

  • Fat Fred Jan 08, 2008

    Me too! Same issue here; the door sometimes starts to open then the
    light goes
    off & it stops. I can tap on the side of the unit and the light
    will flicker and, if I'm lucky and look sideways, tap again, the light
    may stay on. In which case, the door 'may' complete it's ride up or
    down. Not always consistent in working so have to wait awhile, tap it
    again, get a solid light then press remote and it might work.

    Contacted LiftMaster last week via email but have yet to hear from
    them. Left message for the original installer but has not returned my
    call. I, as well, thoroughly checked to see if wires were loose
    but all looked secure. Have a feeling that this is a common issue.
    Purchased my opener in September of 2002.

  • Jeremy Carson Jan 10, 2008

    Actually, I just replaced the logic board and everything works great now. I figured there are only a few electronic parts that can go bad and that was the most logical place to start. Took 5 minutes and $68.

  • Jeremy Carson Jan 10, 2008

    Actually I just replaced the logic board and it works great now! I figured there are only a few electrical parts that could go bad and the logic board was the best place to start. 5 minutes and $68 to fix.



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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

  • sailnc May 15, 2011

    This solution is definitely worth trying! No more difficult than replacing the logic board, and it's free. I tried it on my system which had precisely the same symptoms as others described here, and so far it's working well.
    Just a note -- the connector he's talking about is NOT one of the two that you removed when taking the circuit board assembly out of the main unit. (although I cleaned those up too, just in case). Once you have the 2 circuit boards taken out and on your workbench, you'll remove 3 screws that hold the two boards together, and you'll see the interconnect (I think it was red or rust colored) that seems to be causing the issue.

    Also as another data point - my system was from 2002 as well.

  • Greeny4000
    Greeny4000 Oct 10, 2017

    I did this as well and added a little solder to add a little more width to the connections. So far it works great. Thanks for this idea. Saves a ton of money.


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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

  • Anonymous Sep 02, 2015

    I had the same intermittent power problem: I also shimmed the transformer board to make a better connection to the logic board but didn't do any soldering. I did put dielectric grease on the two cable connectors and the connector that joined both boards together during reassembly...opener works perfect now!



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!
Fat Fred

Posted on Jan 11, 2008

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  • Master
  • 4,402 Answers

Try a new logic boad

Posted on Jan 10, 2008

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