In , jeff_wisnia wrote:
terry wrote:

On Apr 25, 3:58 am, Ivan wrote:

I have a two-tube fluorescent desk lamp that buzzes too annoyingly to
use, but it's a terrific lamp otherwise. Any ideas how to silence it?


There is likely a thing called a ballast (a sort of transformer)
inside lamp base, (not much info provided to go on!) and it may be
slightly loose.Tighten the screws holding the ballast. Glue the
ballast in place/place or jam a piece of something softer maybe
cardboard between ballast and the box/frame etc. Twist the metal case
of the lamp base holding the ballast so it doesn't vibrate. Add weight
to bottom of lamp base? Pour in some cement or heavy
glue ............. !
In other words do everything possible to stop vibration due to the 60
cycle (In North America) frequency of the electrcity being supplied
when the lamp is switched on. Maybe the clamp of the ballast itself is
slightly loose?
We once had a fluorescent tube lamp in the upper part of a cooking
stove that also buzzed, we rarely used the lamp anyway; seemed to be
more of a dress-up item than much practical use. Later found that one
end of the small ballast, which looked much like a small transformer
was secured by one sheet metal screw, while the other end was just
tagged slightly loose into a metal slot. Cheap factory labour saving
construction? Twisting the tag stopped the vibration; took all of five
minutes. Kept the ballast somewhere when we later scrapped the
stove.


If it does have a magnetic ballast, and tightening the ballast mounting
doesn't work you could try what an office maintenance worker "tought me"
a long time ago.

Dismount the ballast, hold it in one hand and give it a couple of whaps
on its side with the ball end of as BP hammer. Make some minor dents to
tighten the case against the ballast lamination stack.

Jeff

I't worked for me a couple of times already.

Sounds good to me!

But anyone else doing this needs to know to hammer over the lamination
stack as opposed to the winding!

The lamination stack is the rectangular portion sticking out in the two
longest dimensions. The winding is what bulges up and down from the
middle of the lamination stack.

(The winding is around a "center leg" of the lamination stack, and goes
through two holes in the lamination stack. The lamination stack is the
"iron core", made of a kind of steel optimized for this purpose in large
part by mixing in silicon to reduce its electrical conductivity. The
lamination stack is made of E-shaped and I-shaped thin sheets/laminations
of this "silicon steel". The winding is around the "center leg" of the
"E", and the "I" is placed against the tips of the 3 legs of the "E".

In most lamp ballasts using an "E-I core" as well as some specialty
transformers where the primary winding conducts significant DC, and
many inductors made with E-I cores, the E pieces point the same way so
that a nonmagnetic gap (often paper) is added in the "magnetic flux
circuit" between a stack of E pieces and a stack of I pieces. In some
lamp ballasts, the E-stack is even welded to the I-stack at the edges,
which causes a minor increase in eddy current loss.
Otherwise, especially with transformers handling pure AC, the E pieces
and I pieces are interleaved.)

So, I offer some details of ballast and transformer construction so that
others trying to silence a ballast with a ball-peen hammer know where to
pound! Pound against the lamination stack - not the winding!

- Don Klipstein )