9V Transformer is Buzzing - Need I Worry?

[Billy]

I have a 9VAC GE security system transformer that began to make a faint
buzzing sound and I'm worried this may be unsafe. The noise started a week
ago after several weeks of it *not* buzzing when first installed - or at
least I never noticed it. The unit does *not* appear "hot".

I changed the receptacle that it is plugged into and checked for grounding
and it is properly grounded. I tested the voltage for 110v with a multimeter
and it is steady at 110. I also swapped the transformer with a new one but
it still buzzes. Finally, I ran the transformer to another two outlets and
it buzzed on both, but each with different intensity.

What could be the cause of this, and how do I fix it? Is this a warning that
it should not be used or corrected?

 

[Steve Cothran]

If you want to fix it, here is how. Find a shop that rebuilds
electric motors and has a varnish tank. Ask them to dip the
transformer for fifteen minutes, or when it stops bubbling.
You can ask them to bake it, or you can take the sticky mess home,
bake it in the oven for three hours at 300 degrees F, and listen
to complaints about the smell.

That'll dang sure do it. Another thought is to ring up my favorite
surplus company (mpja.com) and get another for less than $10. Use 'ol
buzzy for a paperweight.

 

[John]

Its called a hysteresis hum caused by loose laminations I would replace
it cheap enough to do Not likely to happen but it could cause the
insulation coating on the windings to deteriate causing a short
circuit.And please don't correct my spelling