Speaker buzz

[awoodward]

I have a Sansui 9090 that causes a constant buzz in the speakers that is independent of the volume. The buzz exists even when plugged in and connected in place of a newer Kenwood that has zero buzz. Any way to stop the buzz would be appreciated...Art

 

[soundguruman]

There are three things,
One is a ground loop, use an adapter to lift the ground pin of the electrical cord.
use an adapter, do not cut the ground pin off the power cord.
Two is an actual blown transistor inside the unit
Three is a broken input connector, damaged circuit board where the input is.
Does it hum with the input unplugged?

 

[awoodward]

There are three things,
One is a ground loop, use an adapter to lift the ground pin of the electrical cord.
use an adapter, do not cut the ground pin off the power cord.
Two is an actual blown transistor inside the unit
Three is a broken input connector, damaged circuit board where the input is.
Does it hum with the input unplugged?

Thanks for the suggestions.

Ground loop idea: the power chord does not have a third pin and each prong on the plug is the same width. I rotated the plug but it made no difference. Also a newer Kenwood plugged into the same outlet and connected to the same speakers has zero buzz.

answer to "Does it hum with the input unplugged?" If by inputs you mean other components connected to the amp, yes, it buzzes equally whether a turntable or CD are connected or not. If you just connect the amp to the speakers with nothing else in the room running and nothing connected to the amp, it buzzes the same. Also as I mentioned above, I plugged the amp into the same electrical outlet, and connected it to the same speakers as a newer Kenwood (which has no buzz), and the Sansui still buzzed. Maybe I should take it to a repair shop to check for internal problems? or are there things I can still try here.

Thanks again for your help...Art

 

[anwaypasible]

probably easier for the electronics repair shop to hunt down the problem.
maybe it is a broken solder joint.. but usually that means something is seriously not working right if there is still audio output.
otherwise, something is probably just old and aged and needs replaced.

either one might bring new life to the receiver's amplifier.
it might mean a louder output, or a more detailed output.

 

[awoodward]

Thanks,
So I just found a good high end repair shop not to far from where I live. I will take it there tomorrow.

Thanks again for the valuable help...Art

 

[soundguruman]

first, disconnect the cable television from your system completely. Then check for hum again.
Cable TV ground connected to your system can cause this. Check this before you go to the repair shop.
Like for example cable TV is connected to your TV, your TV audio is connected to the receiver. This can form a ground loop.

 

[awoodward]

Thanks for the suggestion. The TV is not connected to the amp in any way. When we unplugged it anyway it made no difference. Still looking...Art

 

[awoodward]

Best answer selected by awoodward.

 

[awoodward]

Problem is not solved. I took it to the high end shop. When the technician plugged the amp in and connected it to speakers -- there was NO buzz.

When we brought it home and plugged into the wall and connected it to our speakers -- it was buzzing again. A Fisher 400 tube amp, and a solid state Kenwood plugged into the same outlet and speakers do not buzz. There is nothing connected to the apm except the speakers.

We cannot figure out why this Sansui 9090 does not buzz at the shop but does at home, while two other amps do not when connected identically. Any ideas...

 

[anwaypasible]

obviously the electricity from the wall outlet at the electrical shop is somehow different than what your wall outlet is at home.
could be a slightly different frequency (it is supposed to be 60hz in the usa)
maybe there is a difference there.
you would have to use an oscilloscope to check the wave pattern to see if there was more or less waves, and also if those waves are taller or shorter.
either one could cause the power supply (or something else) to be aggravated.

maybe the voltages are different.
maybe the electricity for your house is improperly grounded.

 

[awoodward]

thanks for the suggestions, I checked the polarity of all the electrical outlets using a little plug in device for checking GFI. All of them were wired properly. I don't have an oscilloscope unfortunately, or any other equipment for checking precise voltages and alternating current frequency.

I am wondering if it could be something to do with the two TV cable boxes we have. They are not connected to the amp, but are connected to the electrical system in the house, and I guess they also emit some kind of electrical fields. I don't know how to turn them off.

Its weird the other two amps make no sound at all.