Yesterday all of my AC/DC power supplies began making strange buzzing, crackling noise (quickly and intermittently repeated pops). First I thought that my computer's power supply is dying. So I switched to laptop, to my surprise its power began to make the very same noise when I started the laptop. I checked the outlet and there was not problem.
I tryed other wall outlets in the flat too. All of them making this noise. I looked around the house. Other AC/DC converters making this noise too (eg. the main door bell).
But something is strage, the DC appliances and computers still working no signs of overheating or crashing, incandescent light bulbs NOT blinking, AC appliances (like hair dryer) works like before.
Also no electric smell anywhere inside building, pylons seem and sound to be ok. The local transformer just humm.
This crackling noise is quite annoying at night, and it's worrying.
So what can be the source of the noise? And how to fix it? (at least in theory as I rent the flat and I have no tools).
Some technical details: I live in Hungary, the voltage between one phase and ground is 230V, between two phases it's 400V. It seems only one phase installed in the house but I'm not sure.
UPDATE:
Uploaded a Youtube video of the phenomenon:
Best Answer
You have an arc-over somewhere in your power supply system. Electric arcs produce a broad band signal with precisely that noise pattern.
Cracked or dirty insulators on the power poles, transformer with an internal primary circuit fault, loose connections between the transformer and meter, or compromised underground feeder cables that are leaking current between the conductors will probably be the source of this EMI.
Heaven forbid that the source is anywhere in the house, that's a dangerous situation.
Determining where it comes from
Given the noise that can be heard in the video, this should be transmitting a pretty nasty interference on AM radio frequencies to the point you should have no problem using an AM radio as a source detector.
First steps are to make sure this isn't something in the house that is suffering from a loose connection, ground leakage or arc fault. Turn your radio on and with it somewhere mid band between stations, see if you can hear the noise. Now go through the breaker panel or fuse panel and cut power to each circuit till you have cut all power to the house.
If the noise goes completely away from powering off a circuit, then start looking for appliances, switches, lighting fixtures powered by that circuit that that have failures. At this point, if wiring starts being the possible culprit, you're getting into electrician territory, so get a qualified electrician if you're exceeding your technical expertise or what you're allowed to do under your local laws.
Using this method, I had found that the people who wired my house up had used a crimp ground ring to complete a power circuit in the bathroom which explained the radio noise and the dim lighting that would flicker every so often. Removing the electrician's tape off the odd looking connection revealed that the crimp ring (improper use, only supposed to be used in the ground circuit) had worked loose and the copper wire was being slowly eroded from the arcing in the loose connection.
If the power down only slowly diminishes the noise till the last circuit is cut off, then you need to make sure the power entrance and cabling to the breaker panel/fuse panel are intact to clear your residence (qualified electrician time, you do not want to be messing with this).
Once you have cleared your residential wiring, then you need to get the power company involved in hunting down where the noise is emanating from. It's in their best interest to fix it if its a bad splice, cracked insulator or transformer getting ready to blow.