Electrical sound issues

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drZhiv
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Electrical sound issues

Post by drZhiv »

Hello, I'm new here and new owner to this piece of hardware, N2+ 4G. I just had it for 2 days and just succeeded in booting it to coreelec via SD-card.

The board is quiet if only power connected with red led and no boot.

As soon as I boot the board there is high pitch electrical noise (heard meters away, enough to be annoying) coming from the board, And it continues after booting to the core elec start menu (latest version).The noise seems to change in character a bit when I plug in a USB mouse or keyboard.

The hardware seems to work otherwise. But having this noise in the background with film/tv sound is not going to be fun with the hifi-system. Is there anything one can do?

Edit: The noise issue is the same with the Ubuntu Mate that came with the EMMC module.

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Re: Electrical sound issues

Post by mctom »

Hi!

Never seen anyone with such complaints on this forum. I own the same model and would definitely notice something like that.

From what you describe, the sound is probably made by a power converter inductor. Normally power converters are designed to work in frequency range above human hearing. Unless your hearing is extraordinarily good, there is something wrong with your unit.

If connecting USB device changes the pitch, or pattern, it might suggest 5V source is faulty.

But before I encourage you to replace the unit, perhaps it's not a bad idea to ask someone else if they could hear it too. Seriously. As a kid I couldn't stand some certain CRT TVs for this reason. At this age, maybe not so much. Also, CRT TVs are gone.

Also, please tell us what kind of power supply do you use and if there is any chance of trying a different one.
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Re: Electrical sound issues

Post by drZhiv »

mctom wrote:
Tue Oct 12, 2021 5:05 am
Also, please tell us what kind of power supply do you use and if there is any chance of trying a different one.
I'm using the official one with attachable EU-plug, that I bought with the board.

I' sure the sound would be heard by anyone with normal hearing. Maybe the sound would be less noticable if used in a case, but that is probably wrong way to go if it is broken.

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Re: Electrical sound issues

Post by odroid »

If the noise could be heard from a couple of meters distance, there might a hardware problem with an inductor of DCDC converters.
Where/when did you purchase your N2+?

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Re: Electrical sound issues

Post by mad_ady »

You can use a smartphone with an app like phyphlox to get a frequency graph for the audio and work out the frequency of the sound. But yes, sounds like a broken/loose inductor coil.
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drZhiv (Tue Oct 12, 2021 6:48 pm)

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Re: Electrical sound issues

Post by rooted »

mad_ady wrote:You can use a smartphone with an app like phyphlox to get a frequency graph for the audio and work out the frequency of the sound. But yes, sounds like a broken/loose inductor coil.
Spectroid works a treat for pinpointing a constant sound.

https://play.google.com/store/apps/deta ... t.spectrum


Image
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drZhiv (Tue Oct 12, 2021 6:48 pm)

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Re: Electrical sound issues

Post by drZhiv »

odroid wrote:
Tue Oct 12, 2021 11:17 am
If the noise could be heard from a couple of meters distance, there might a hardware problem with an inductor of DCDC converters.
Where/when did you purchase your N2+?
I ordered it in the beginning of this month, october, from kksb-cases.com (r-pi.se) (Gothenburg Design AB). If I'm reading correctly it says "Rev 0.6 20210121" on the board.

Thanks for support!

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Re: Electrical sound issues

Post by drZhiv »

mad_ady wrote:
Tue Oct 12, 2021 3:51 pm
You can use a smartphone with an app like phyphlox to get a frequency graph for the audio and work out the frequency of the sound. But yes, sounds like a broken/loose inductor coil.
I took a screenshot of the measure i did with Spectroid, holding close to board at kodi homescreen (using an older android phone so not sure how accurate it is).
Screenshot_20211012-150856_Spectroid[1].png
Screenshot_20211012-150856_Spectroid[1].png (340.19 KiB) Viewed 237 times

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Re: Electrical sound issues

Post by mctom »

Looks like background noise and nothing more to me. A few lines on the lower half are probably gentle taps on the phone.
The noise coming from N2+ is probably above 8kHz, which is filtered out by the phone itself.
If this is the case, you may be gifted with wide hearing range after all. ;)
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Re: Electrical sound issues

Post by drZhiv »

Yea the phone is not picking up the noise. But its very much there, like when you're outside hearing grasshoppers/crickets. That's the best I can describe it. Do you guys think it's best to ask for a replacement unit. Unless something else to try?

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Re: Electrical sound issues

Post by odroid »

I could hear some electrical sound only if ambient is very quiet and my ear is very near (less than ~0.3 meter) to the inductors.
Maybe it's because my ears are old and dull, but I couldn't hear the noise unless I was very focused.

Try a replacement.
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drZhiv (Wed Oct 13, 2021 4:49 pm)

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Re: Electrical sound issues

Post by drZhiv »

odroid wrote:
Wed Oct 13, 2021 10:14 am
I could hear some electrical sound only if ambient is very quiet and my ear is very near (less than ~0.3 meter) to the inductors.
Maybe it's because my ears are old and dull, but I couldn't hear the noise unless I was very focused.

Try a replacement.
Yea, usually I only notice such sounds very close (I'm not that young also). I will try replacement :)

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