On 28 Feb 2007 20:09:39 -0800, "
wrote:

On 28 Feb, 20:05, "
wrote:
I have no experience with electronics except dabbling with a
multimeter.

I wanted to silence a humming transformer, I read somewhere that
covering it in JB Weld would do the job. But I didn't even get
that
far.

I struggled to open it up, in the end I managed it quite 'easily'
with
a hammer.

Before even putting on any JB Weld, I put the lid back on it and
plugged it in.

Then I flicked the mains power switch and bang it blew.

I know it was the ACDC adaptor because and not a mains plug fuse
because the power cord still worked in another ACDC adaptor

Is there a way for me to open one of these things without
encountering
that?
does anybody know about silencing humming / whining transformers

Here are pictures of the transformer
http://img152.imageshack.us/img152/262/15084473gh0.jpg
http://img339.imageshack.us/img339/954/18933823la0.jpg
http://img339.imageshack.us/img339/3033/19265605dw7.jpg

I know the AC-DC adaptor sits on a book about electricity, but it
hasn't been read, I don't have any background in the subject!



Unless I'm mistaken the transformer you refer to is a fairly standard
E core ferroxcube switch mode type. The cores are generally stuck
together with epoxy or other suitable adhesive at manufacture. If the
adhesive between the faces of the two E cores comes adrift you will
hear a high pitched squeal and possible even a rattle. I would not try
to fix this by covering it with any sort of gunk (or JB Weld). The
transformer should be unsoldered from the board and the two E cores
removed, their mating faces scraped clean and then re-glued under
pressure.

Sometimes only one face may have come unglued so you have to heat the
transformer core to a reasonably high temperature (I use a hot air
gun) in order to soften the remaining bonds so you can get the cores
apart.

Re-gluing with epoxy adhesive is good and will definitely fix your
squealing transformer. I have also used Cyanoacrylate (superglue) to
rebond core faces.