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Washing Machine Hum and Buzz

Napzca

Napzca

Active Member
The Washing Machine is causing my Amplifier to hum and buzz loudly. Is there a way to rectify this? I only have one ring main for my sockets. Could there be a leakage of current to the Ground or is it causing distortion of my waveform? Can I filter out the noise by plugging a filter before the washing machine? Would a separate ground remedy this? Your help is appreciated.
 
I am no expert and I can’t claim to have ever connected an oscilloscope to the output of the mains but received wisdom says transformer hum is caused by a D.C. offset on your supply which I am not sure tallies directly with your washing machine theory. Anyway I am sure somebody will come along shortly and put us both straight as is the way on PF.
 
When you say noise from your amp do you mean through the speakers or mechanical noise from the transformer.
Afaik washing machines have dc motors to get the speed range between wash mode and spin mode.
 
Do not under any circumstances connect an oscilloscope to your mains unless you know what you are doing.

The likely problem is spikes being put on the mains by the washing machine, which may be faulty. A suitable filter may help, or do the washing when you are not listening to music.
 
It is mechanical hum of the transformer. I am worried the vibrations in the transformer are doing it damage ie could degradation of the toroidal transformer occur causing more hum? The washing machine seems to work ok.
 
Also try plugging the amp in right by the washer, less mauling than the other way round.
 
The fact that the washing machine seems to work O.K. doesn`t mean it`s not faulty, it`s own suppressor may be faulty or some problem in the motor circuit could be causing excessive noise on the mains. What about other equipment on the same circuit - TV for instance?
 
Don't want to replace the washing machine it's only a few months old. The interference doesn't affect any other equipment. Just the Amplifier.
 
The xformer buzz is caused by DC offset on the mains. If its the washing machine causing this then it may be missing or need a transient suppressor wired across the motor. It sounds grand but its just a resistor (around 100Ω or so) and a suitably rated capacitor (around 0.05µF) in series across the motor. Sometimes you can buy these as a sealed suppressor unit.

Cheers,

DV
 
I tried a Tacima Mains Filter, it didn't have any effect. Thanks DV you were right if I put a humbuster III which blocks DC voltage on an AC line it stops the hum, but I don't want to use this long term.
 
They refer to the three phases on a three-phase supply. No good for your machine as domestic mains is only single phase.

That's also rated for use at 400Hz so is intended for aircraft ground supply systems!
 
Napzca said:
Will this motor suppressor do the job? What does U, V and W stand for?

23050_zoom by Napzca, on Flickr
Click to expand...
Are you in the UK or Europe? In the UK our domestic supply is single phase and this is the sort of thing I was talking about https://uk.rs-online.com/web/p/surge-suppressor-units/0240393/

However unless you really know what you are doing wrt to mains electricity I'd suggest you get someone qualified to do the work. Before that why not disconnect the machine from the mains and check whether there is already a suppressor fitted across the motor and if so is it still properly connected.

When I lived in Germany we had a 3 phase mains supply so things were wired differently.

Cheers,

DV
 
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