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This anomaly is occurring on both of my garage door openers, and began about the same time. One of them also stopped working at all after about a month, and I had to replace the motor start capacitor to fix it. However, they both won't receive a signal from the remote while the light sockets in them are engaged as on. Bulbs removed, same issue. Once the click occurs that turns the light sockets off, it works normally. Odd that they would both get this problem at the same time. I did add a "Ting" power monitor on a plug in the house which monitors the power grid in the home, but the symptoms continue even when I unplug it. Anyone have a suggestion?

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  • Trying to understand your question... this part seems key: "Once the click occurs that turns the light sockets off, it works normally". So even with NO load (ie bulbs not in place, activating the switch for the lights causes the garage door to cease functioning. Sounds like the light switch is wired incorrectly, possibly even dangerously. Can you clarify a bit, maybe more info on that light switch?
    – mark f
    Commented Dec 7, 2021 at 18:36
  • Do the hard wired wall switches both work to open and close the doors regardless of the condition of the light circuits? It's just the remotes that don't work, and only when the lights are switched on? Is this strictly with the light circuits built into the opener units, not your separate ceiling or other house lights? Does this happen regardless of distance, even if you stand with the remote next to the opener in the garage?
    – jay613
    Commented Dec 7, 2021 at 20:24

2 Answers 2

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I had a similar issue with two ten year old openers that failed at the same time. My issue is like what xeeka mentioned.

In my case, the large cap for smoothing out the 5v power supply went bad. When the relay for the lights is energized, it makes the ripple too high on the 5v supply and destabilizes the receiver. Diagnosing requires familiarity with electronics and an oscilloscope.

Googling "5v capacitor liftmaster" shows that others have had the same issue as I did. Perhaps you have the same issue. If you can solder, you could just replace the filter cap without diagnosis in hopes that is the problem.

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  • you might not need to replace the cap, it can be added in parallel to curtail desoldering the old one, if the old cap is lower capacity and hasn't gone low-resistance (which seems to be the cases given partial success). You can also replace the relay with a DC SSR so that hold current needs are minimal.
    – dandavis
    Commented Dec 8, 2021 at 18:17
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A lot of capacitive power supplies are producing that issue. Reason could be strong thunderstorms with lightings or inductive equipment nearby (motors, compressors, A/Cs) that cause voltage spikes in the 110/220V~ domestic net.

Those spikes can reduce the capacitance of the capacitors, which are often self-healing. But the capacitance is reduced.

Another reason could be aging of components in that power supply. But if both failed at the same time, an external reason seems more likely.

As result, the output voltage and/or power which is delivered by the capacitive power supply of the garage door opener is reduced to a level, where the electronics like the processor or radio receiver is no more working as it should (frequency shift, decreased sensibility, not working at all etc.)

The lamp sockets - assumed to be part of the garage opener - which are switched by a relay (click sound) do need much more power if in state "on" compared to state "off", since the relay needs energy to hold the contacts together.

An indication might be that switching to the state "off" is more difficult than switching to the state "on" - and the opener is less likely to work when the sockets are on, as described by the thread opener.

Those capacitive power supplies are directly connected to dangerous high voltage and must not be opened/repaired/tuned.

To protect the domestic net (or long garage lines) from spikes, special overvoltage-protection is available for electric panels and boards (level 2).

Just as information for experts - the following is NOT a repair instruction:

an exchange of that capacitor which serves as voltage divider may solve those issues. For a check, a small capacitor can be temporarily attached in parallel. Mostly, the capacitors are in the range of 100 nano Farad to 680 nano Farad. They must be of type X2 or better (often X2 types are yellow with UL/VDE/ labeling).

A calculation of the new circuit with new capacitor is necessary if the capacitance is increased - sometimes brand new capacitive power supplies are not well constructed and have capacitors that are too small right from the beginning (warranty, legal issue).

That calculation is important for other electronic parts like series resistors (power loss), diodes/rectifiers (current/peak current, power loss) etc.

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