[sdiy] aging transformer replacement

[Glen]

At 04:47 PM 6/10/04 , jhno wrote:

>several of my devices start to hum/buzz acoustically after being powered up
>for a while - typically 0.5 - 2 hours, say. it is the transformers, of
>course. i imagine they are just getting old.

Before you assume all of them need transformers, you might want to
investigate whether there is some sort of overloading that is occurring.
It's possible that one or more of your synths is drawing excessive current,
and that can make the transformer hum noticeably. One would think that
fuses would be blowing if that were the case, but I've actually seen a
transformer blow, apparently to protect the fast-blow fuse connected to it
from harm.   :)

Also, some transformers are mounted on shock-absorbing rubber mounts.
Sometimes these rubber mounts will deteriorate over time, and the
transformer establishes a loose metal-to-metal contact at its mounting
points. This can make an audible hum, where previously there was none. In
this case, you need replacement rubber mounts.

Sometimes transformers that are solidly bolted down from the factory, with
full metal-to-metal contact, will develop one or more loose bolts or loose
nuts. This can also cause audible humming. The cure here is to simply
re-tighten the nuts or bolts of the transformer.

Of course, it could be the fault of the transformer itself. I think some
people have methods to quieten a noisy transformer, but that's something I
don't have personal experience with. Maybe someone else on the list can
help you with info on that.


later,
Glen
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