[vexborg]

Hopefully some aduio buffs in here can help me out?

I've got a Hitachi AX-M135 Home stereo with a built-in 40GB hard drive - and this stereo has an extremely annoying humming noise, the noise is audible even if the music is playing or not, of course when the power is off, no noise is there.

The humming noise can best be describe as a cycling 60Hz noise.

I've tried the following:

Moved the stereo to another outlet on the wall.
Put a new plug at end of the power cable.
As I thought that it might have been the speakers, I disconnected them, and played the music only using a pair of headphones - the noise was still there.

To be honest I don't know what to do anymore (not that I've tried that much).

I can only think it might be a grounding problem, but how do it get the stereo grounded? As it is now, the plug at the end of the powercable is a standard UK 3 pin plug which supposedly has a grounding pin.

Any ideas?

[Goldfinger]

I got the same with my Sony Receiver, playing things like classical music through the headphones is impossible. The hum makes me go nuts. Through the speakers it's the most apparent through the center speaker (if it decides not to cut out for once).
I tried it in different outlets, other rooms (every room has it's seperate circuit in our house), at a friends place.
The hum is still there, it's been in for repair twice, they never fixed it.

My previous amps never had it. I blame it one the power supply in the receiver. Ah well, I'm saving up for a Denon or Pioneer to replace this (somewhat highly regarded) Sony POS.

[vexborg]

I wish I could replace the amplifier with something else, but since this system is connected via something which best can be described as a IDE cable, this won't be a solution for me

[residentEvil]

you man still have a ground loop problem.

also do you have any appliances on the same circuit (i didn't say outlet)?

[vexborg]

Originally Posted by residentEvil 

you man still have a ground loop problem.

also do you have any appliances on the same circuit (i didn't say outlet)?

Well, before I moved the stereo it was in the same circuit as the TV and DVD player, but then I moved it to another outlet where it is the only thing connected. That didn't help...

Any suggestions as to what to do?

[residentEvil]

appliance = fridge, etc. something with an electric motor that cycles. it may be coming back thru your circuit panel anyway. you tried another outlet; but that could be the same circuit as the one you are now.

as i said; don't try another outlet...but try a different circuit. a circuit can have many outlets on it. you may be trying the same circuit.

[analogika]

Do you have a light dimmer in the same room?

[vexborg]

Originally Posted by residentEvil 

appliance = fridge, etc. something with an electric motor that cycles. it may be coming back thru your circuit panel anyway. you tried another outlet; but that could be the same circuit as the one you are now.

as i said; don't try another outlet...but try a different circuit. a circuit can have many outlets on it. you may be trying the same circuit.

Ok, as far as I can understand, our house has 2 circuits - one on the lower floor, and one on the upper floor.

The problem is still there no matter if I connect the stereo on the upper or lower floor.

[vexborg]

Originally Posted by analogika 

Do you have a light dimmer in the same room?

Yes, the livingroom has a dimmer swicth, not used when the stereo is playing.

[jokell82]

Try putting a ground lift on the stereo. You can get a plug that costs less than a dollar to put on the end of your power cord. It'll turn your grounded plug into an ungrounded plug. If you put one of these on and the hum goes away, you have a ground loop issue.

Here's what the plug looks like in the US:
http://www.american-allergy-supply.c...1-2720plug.jpg

[analogika]

Cheap dimmers are notorious for ****ing up electricity. However, if the thing is completely switched off, and other electric devices are also disconnected from the mains, and the hum persists, it might just be an electrolytic cap in the amp's power supply that's dying. Cheap to fix.

[residentEvil]

I highly doubt your house only has two circuits.

Oh well.

[vexborg]

Ok, while this tread has been going, I've tried to use a modified plug - this time with a plastic grounding pin, and that didn't make any difference at all.

I guess it might be time to get the stereo down to the seller and see if they can solve the problem, if not, I'll see if I can get the money back or get an replacement. It still has 6 months of warranty left.

[Weezer]

My speakers used to hum, but then I got one of those "clean power" surge protectors, and the hum went away..

[vexborg]

Originally Posted by Weezer 

My speakers used to hum, but then I got one of those "clean power" surge protectors, and the hum went away..

That's worth a try.

[Goldfinger]

Originally Posted by analogika 

Cheap dimmers are notorious for ****ing up electricity. However, if the thing is completely switched off, and other electric devices are also disconnected from the mains, and the hum persists, it might just be an electrolytic cap in the amp's power supply that's dying. Cheap to fix.

Is there a way to test those electrolytic caps ? How much do they cost ? I'm thinking of maybe replacing them all in my receiver. The damn thing is out of warranty anyway, don't care if it dies on me. My soldering skills are adequate

I have a "clean power" surge protector already.

[G4ME]

many power conditioners vary on what they actually do, if you want do some research and pick one up thats worth is cost.

Panamax is one company that makes a great product, but if its constant and you tried a "cheater" plug sounds more along the lines of the PSU is real crap and no matter how clean your power is, you won't get rid of that hum.

Time to break out the rosin core and breath deep

[macintologist]

My el cheapo logitech 2.1 computer speakers don't hum

[Railroader]

Originally Posted by macintologist 

My el cheapo logitech 2.1 computer speakers don't hum

I think I'd rather hear the hum.

[G4ME]

for the price, those logitech arn't that bad, deff worth the 30-40 bucks they charge at my uni comp store.

you just need to realize they are only 40 dollar speakers and treat them as such.

[Railroader]

Originally Posted by G4ME 

for the price, those logitech arn't that bad, deff worth the 30-40 bucks they charge at my uni comp store.

you just need to realize they are only 40 dollar speakers and treat them as such.

I'll stick with my Tivoli Audio. k-thx.

[awaspaas]

I had that problem with my first receiver (a Sony) - I brought it back for a replacement that same day and the new one was fine.

[vexborg]

Originally Posted by awaspaas 

I had that problem with my first receiver (a Sony) - I brought it back for a replacement that same day and the new one was fine.

It is starting to look like a replacement is the only solution for me - oh well, hopefully they'll have the same in stock...

[Goldfinger]

Originally Posted by awaspaas 

I had that problem with my first receiver (a Sony) - I brought it back for a replacement that same day and the new one was fine.

What type if I may ask ?

[awaspaas]

I don't recall the model number - it supported 5.1 inputs but didn't have a Dolby Digital or dts decoder. I believe it was 90 or 100 watts/channel.

[Severed Hand of Skywalker]

Every time I have had buzz issues it was because of grounding.

[centerchannel68]

Yeah. It could be a cap, but that usually only happens in old equipment. I'd just replace it dude... get something else off craigslist.