[sdiy] Fixing humming transformers in 1u rack units

[Altitude]

Pardon me if this is common knowledge but for me it was quite a revelation:

I have/had a couple of rack units that have a hum when turned on (M1000 and
Tx-81z specifically) which is rather irritating.  Some quick research
revealed that this is caused by magnetic flux from the transformer vibrating
the top of the case and the general solution I could find was a vague "cover
it with something". So finally got around to looking at this on my TX and
per the Tx-81z service notes which has a diagram of the fix, all that needs
to happen is a metal shield needs to be clamped on top of the transformer. I
used 0.016" thick cold rolled steel which is nice and formable but rigid
enough to hold its shape so just bending the flanges in is enough for it to
clamp on to the transformer.  Not sure if aluminum would work or not, the
steel works great.  The trafo is conformal coated so it is not electrically
connected to anything.

The results are perfect. The hum is completely eliminated. I wish I tried
this earlier when I still had my Martrix 1000.

Pics:

http://midiot.net/TX_side1.jpg
http://midiot.net/TX_side2.jpg
http://midiot.net/TX_top.jpg


Cheers,
Alt

 

__________ Information from ESET NOD32 Antivirus, version of virus signature
database 4881 (20100219) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com