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Old 3rd February 2017, 11:40 PM   #1
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Question Amplifier noise - please help!

Hi all,

I have a soundbase from Ricco model T2122 which started to make this buzzing as soon as it's turned on.. Sample here
There's no specific reason related to it, it just happened suddenly.

I took it apart but main board seems fine - please have a look at the images.

Also, I found a power supply with identical specs (15v 3A) and tried it but the noise is still there.. what can it be?

Thanks in advance!
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Old 4th February 2017, 03:14 AM   #2
farley is offline farley  United States
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Does the noise occur when your cell phone is next to, or on top of, the amp? The noise sounds similar to what I hear when my cell phone is next to my bedside radio.
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Old 4th February 2017, 10:56 AM   #3
AndrewT is offline AndrewT  Scotland
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Sounds like interference coming from some other location.
And it turns itself ON OFF periodically.
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Old 4th February 2017, 11:04 AM   #4
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i hazard its some bad capacitors charging up and giving a noise.
8 would change the big electrolithic caps at first shot.
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Old 5th February 2017, 03:28 PM   #5
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Thanks all for your replies!

The strange thing is that the noise recorded was with all cables unplugged so no input signal and far from any mobile or radio source...

The big caps are Panasonic, I've replaced the 4 of them myself about 4 months ago based on the exact same specs as the initial Chinese ones.. - would this cause the noise?!


Thanks!
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Old 5th February 2017, 05:52 PM   #6
AndrewT is offline AndrewT  Scotland
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open inputs with a poor enclosure that lets in interference will make a noise. long slots will pass interference even if they are only 0.1mm wide.
You must have a source of emi in the house, or nearby. Something that repeatedly changes even few seconds. An SMPS that is hardly being used and it turns itself on to top up the charge?

You need to add some RF attenuation to your cable entries and maybe look at how to improve the enclosure.
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Old 5th February 2017, 06:18 PM   #7
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My first reaction would be to take it somewhere else, a friends house and see if it is interference (conducted or radiated) if the problem exists it my be internal to the box.
Next I would run it off a battery, say 10 type AA batteries, it should power the device for a while, that way you can establish if it is power supply related.
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Old 6th February 2017, 04:36 PM   #8
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short the INPUTS and see if the noise is still there or if it had changed any.
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Old 11th February 2017, 06:29 PM   #9
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perhaps the RCA cables going bad? happened to my system last week ... check everything turned out to be the cables ... sometimes it is not the amplifier fault that create these noises but caused by low quality RCA cables which connects the source with the amplifier. What actually happens when using an RCA cable with poor shielding, the poor shielding would not be able to prevent the noise from interfering with the actual wire (inside core of the RCA cable) that carries the audio signal ...
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