Step-up Transformer
 

Hey guys,

I brought a heap of gear from Ausi to Japan that needs 240v, so I of course have to use a step-up transformer.

I have been using mine for a period of about 6 years, and recently it's started to make a humming noise. It's quite loud and it only appears once it's warmed up by the looks. Really pisses me off though.

I am wondering if any of you tech guys know what may be going on with it.
Is this normal wear and tear for something like this?
Could it screw up any of my gear attached?
Can I do anything to fix it?

This is a heavy duty step-up, weighs about 7 kilo, and could power almost the whole studio if I let it. I really don't wanna buy another one.... :(

Any ideas?

Since no one else has any input... My limited experience with this and your description of the problems suggests one of the transformers is acting up. A lot of power conditioners and transformers will go bad over time.

Is the hum new? Could something that you've got plugged into the transformer be kicking up noise like a laptop power supply or display? Try unplugging everything from the transformer and adding things in one by one to see if you have a noise maker in the bunch. If possible, try hooking the transformer up to another circuit in the studio if you have one. Do you have some gear powered through the xformer and some hooked directly up to the wall? If so, you may have yourself a ground issue. That might be difficult to address, but balanced cables could help. Give those things a stab and post back! Good luck

From what i´ve read it could be DC on the AC line. Here´s a thought: Maybe there has always been DC on your AC line but your step-up transformer might have been filtered it away (until now). Now think if a capasitor has shorted. Now the DC doesn´t get filtered anymore and the transformer starts to hum. Just an idea...

Here´s a link to someone selling hum eliminators with some info on the isue: http://www.psaudio.com/articles/hum.asp

A transformer consists of 1 or more coils of copper wire wound around 'laminations' which are thin sheets of steel placed on top of each other to form a block.

With age these laminations can get loose and start to vibrate at the same frequency of the supply...this is normal but can be annoying.

I have heard one person recommend pouring some super glue into the gaps between the laminations on all sides of the block in order to stop them vibrating but I don't know if this will work...worth a try though since large transformers cost a packet.

Either that or put it in a soundproof box...or another room :D

Reading this again... is it a mechanical vibration from the unit itself? I WAS understanding it was causing a ground loop. If it's just a mechanical hum that's not unusual at all.

Thanks for the replies everyone.

Yep, it's a mechanical hum. I think it's just down to the age of the thing itself.
I have read up about magnostriction (think that was what it was called), and how vibration can occur. Just a bit pissed that it has to happen in the studio. What can you do I guess.....

hehe super glue isn't a bad idea - don't think I'll try it just yet though. Maybe I'll wait till I get a fire blanket or similar ready. :)

For now, I have cased it (not tightly) in some sound proofing and put it as far away as possible in a roomy cupboard.
It's doing the trick, but it won't be the best once summer comes around.