there are 5 relays inside arcording to the eevblog teardown video,
3 of them are bistable type, so i dont think they can do this.
it sure sound like fast random drive signals to a relay.
i did ask my supplier for permission to open, and track down the problem for them,
(NON void warranty of course, hopefully they say yes.)
since it is very rare to see this, i feel they will never be able to find the problem or the cure,
and also we need to know ?? is it just a simple defect in my unit ? or a general design issue ?
will other similar units do this too ? same age, serial range ?
please check, if you own one, let it stay with mains, but power off on the front, put it where you sit and sleep
so you detect the weak audio sound
it seems like it happens a little bit more often, the first hr after mains is applied,
or like in the video, i just put it down on the ground, i could feel cold air from garden door,
so it might be affected by temperature or humidity
my plan : solder wires to the two standard relays coils,
connect to scope, set trigger, and memory mode, let it run a few days, and then i will have all the coil pulses stored for research,
then i also want to monitor supply voltage of the standby system,
and maybe also mains voltage, just to isolate all input variables.