Buzzing crackling transformer

The item labelling looks dubious. They quote 18 watts in and 18 watts out so 100% efficient and then show a warning that it can get very hot. WTF.

They should not make a noise unless perhaps are being overloaded and are protecting themselves

crackling from electrics means sparking. Remove from service immediately.

NT

Agreed but if a supersonic switchmode PSU is self protecting under overload conditions it usually ticks at a few Hz from the transformer which could be described by the OP as a crackling sound?

maybe so. Do you want to gamble, bearing in mind the dubiousness of the unit at the best of times? Are you feeling lucky?

NT

Or they are just made very poorly and are rattling due to being quite hot and the glue inside has melted or moved due to expansion and contraction. Though probably not actually dangerous, I'd think replacing them with better quality items for peace of mind and less annoyance factor should be a priority. If they are under warranty, then in my view making excessive noise when used for their intended purport is a good enough reason to reject them, whatever else you might think. I once had this with the PSU supplied with something and after some negotiation got it replaced. It turned out it was actually intended for a different market but was OK in the UK except that it got too hot to touch in use. Crap. Brian

Those CE markings look fake to me, the letter look too close together and a bit to elongated. But atb least being ebay you can send themn back if they are working.

they're probably the ones that mean: Chinese Export/

Yes.

The Red and Black tails in the terminals marked Brown and Blue are not a good sign either.

Stevew