High Frequency Hum/Buzz from HAI &SA UPB Light Switches

[Chassmain]

Hey friends, I've got over 50 HAI 35A00-1 Dimmer Switches that have developed an annoying hum at night. Oddly it doesn't happen all the time, but when it does you can hear this study high-frequency hum/buzz coming out of the switches. Definitely audible enough that you can hear it across the room.

Any idea on what could be going on or where I should look. They didn't always used to do this.

 

[electron]

Does it sound like the buzzing you hear when UPB commands are sent/received?

 

[RobinsonNi]

Hi,
I have noticed this too, it’s always there (constant). It’s not the UPB commands because it’s a different buzzing sound.
It can get very annoying from time to time!

 

[Chassmain]

Mine isn't always there, some nights it is, some mornings it is… This persistent high pitch hum… Can't figure it out.