Extremely high pitched (unwanted) noise coming from electronics...
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kc koellein
Jun 22, 2012, 1:40:30 AM6/22/12
to X-otic Computer Systems of San Antonio, 10BitWorks on behalf of shazzner
Ladies and Gentlemen...
Latest quiz is in reference to quite a pain in my eardrum...
We have two appliances now that emit a very high pitched ringing when plugged into the 120vac. They are so high pitched that some in my family cannot hear them... but those who can it drives us nuts!
One, a rather old 9inch portable television... when the tv is turned off, but still plugged in... makes this sound... when we pull the cord... it goes away after a few seconds, like a capacitor was feeding it for a while afterward. if we leave it turned on, the sound is not there... but THAT drives me mad wasting the electricity.
The other... my brand new Chinese ham radio... the charger base station for it. did NOT do it the first couple of hours... just started when I docked it to go to bed. I had it in and out of the base all night carrying it around. it only does it when 120vac is plugged in... if I switch to alternative 12v dc from an external wall wart, it does not make the sound...
120vac - 8.4vdc transformer...? or likely... something in the filter circuit..?
Ideas any and all are welcomed!
thx,
kc
as I typed this message... after 10-15 minutes of the annoying micro-ear-split... the radio base station's disturbance-noise faded out. I thought my ears were breaking, but I just confirmed... no... it is not making the sound anymore. I'm sure it will come back. any educated guesses as to what it might be are appreciated.
Latest quiz is in reference to quite a pain in my eardrum...
We have two appliances now that emit a very high pitched ringing when plugged into the 120vac. They are so high pitched that some in my family cannot hear them... but those who can it drives us nuts!
One, a rather old 9inch portable television... when the tv is turned off, but still plugged in... makes this sound... when we pull the cord... it goes away after a few seconds, like a capacitor was feeding it for a while afterward. if we leave it turned on, the sound is not there... but THAT drives me mad wasting the electricity.
The other... my brand new Chinese ham radio... the charger base station for it. did NOT do it the first couple of hours... just started when I docked it to go to bed. I had it in and out of the base all night carrying it around. it only does it when 120vac is plugged in... if I switch to alternative 12v dc from an external wall wart, it does not make the sound...
120vac - 8.4vdc transformer...? or likely... something in the filter circuit..?
Ideas any and all are welcomed!
thx,
kc
as I typed this message... after 10-15 minutes of the annoying micro-ear-split... the radio base station's disturbance-noise faded out. I thought my ears were breaking, but I just confirmed... no... it is not making the sound anymore. I'm sure it will come back. any educated guesses as to what it might be are appreciated.
Chris Hardee
Jun 22, 2012, 8:44:02 AM6/22/12
to 10BitWorks on behalf of kc koellein
From my experience, it happens with cheap electronics that are not
properly filtered. The capacitors in them basically start vibrating at
an audible high-frequency, and those that are sensitive can hear it.
A friend of mine replaced three computer power supplies in a row
because they were so noisy. I'm not sure what you can do; I've plugged
them in a power conditioner, which didn't help at all. Some people
open the electronics up and hot glue around the offending parts.
Not too sure, maybe someone with a better EE know-how can answer.
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properly filtered. The capacitors in them basically start vibrating at
an audible high-frequency, and those that are sensitive can hear it.
A friend of mine replaced three computer power supplies in a row
because they were so noisy. I'm not sure what you can do; I've plugged
them in a power conditioner, which didn't help at all. Some people
open the electronics up and hot glue around the offending parts.
Not too sure, maybe someone with a better EE know-how can answer.
> You received this message because you are subscribed to the Google Groups
> "10BitWorks" group.
> To post to this group, send email to sa-hack...@googlegroups.com.
> To unsubscribe from this group, send email to
> sa-hackerspac...@googlegroups.com.
> For more options, visit https://groups.google.com/groups/opt_out.
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Chris Hardee
10BitWorks
San Antonio Hackerspace
10bit...@gmail.com
http://10bitworks.com/
kc koellein
Jun 22, 2012, 12:48:01 PM6/22/12
to X-otic Computer Systems of San Antonio, 10BitWorks on behalf of shazzner
Gee, thanks for the responses guys! Good stuff...
Like I said, the radio does it intermittently so far... I just came into the room where it is and it isn't doing it at the moment. It wasn't doing it anymore when I left it last night.
The old TV will do it like clock work. Probably similar issues only in different circuits. I think I will consider taking the TV apart... but I'm not sure about the radio base... since that has a warranty and all... I may call and inquire.
Now that I think of it... I have some USB wall warts (1 or 2 of them) that do this high-pitched thing, too...
Just for grins, I'm checking my AC voltage now... and when it happens again, I'll check again.
kc
Like I said, the radio does it intermittently so far... I just came into the room where it is and it isn't doing it at the moment. It wasn't doing it anymore when I left it last night.
The old TV will do it like clock work. Probably similar issues only in different circuits. I think I will consider taking the TV apart... but I'm not sure about the radio base... since that has a warranty and all... I may call and inquire.
Now that I think of it... I have some USB wall warts (1 or 2 of them) that do this high-pitched thing, too...
Just for grins, I'm checking my AC voltage now... and when it happens again, I'll check again.
kc
On Fri, Jun 22, 2012 at 12:47 AM, Aaron Osmer <ajo...@gmail.com> wrote:
As far as I can tell, that symptom is usually caused by a filter capacitor in the switching power supply of the device. It seems to be a tolerance matching issue where the capacitor is theoretically in the right voltage range, but can't actually handle voltage spikes that occur. This causes the capacitor to either lower in value or increase in resistance and stops filtering the switching frequency correctly. I'm not sure how you can find this capacitor or if replacing it will help, but you can always try.
-Aaron Osmer
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Donald Greer
Jun 22, 2012, 1:22:36 PM6/22/12
to 10BitWorks on behalf of shazzner
I've also seen (heard?) that high-pitched whine from transformers. The laquer between the coils breaks down over time (or due to heating) and allows a tiny spark-gap between two windings that generates the noise. This was really common on cheap TV flybacks in the 80's and cheap monitors in the 90's (of course some of you young'ns won't remember TV flybacks ;^).
If this is the case, the only fix is to replace the PS and try to get better ventilation or some other way of cooling the transformer better. Or just get a better PS that can handle the heat better.
If this is the case, the only fix is to replace the PS and try to get better ventilation or some other way of cooling the transformer better. Or just get a better PS that can handle the heat better.
Don
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"I don't necessarily believe that software should be free, but if you pay for it, it should work." -- Me
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"I don't necessarily believe that software should be free, but if you pay for it, it should work." -- Me
kc koellein
Jun 22, 2012, 1:38:47 PM6/22/12
to 10BitWorks on behalf of Donald Greer
We still keep using this TV after all these years..
and I have no intentions of getting rid of it... it still has an analog tuner...
you never know. that just might come in handy in a zombie apocalypse survival situation. I'm gonna hang onto that sucker. Fixing it is definitely an option.
kc
and I have no intentions of getting rid of it... it still has an analog tuner...
you never know. that just might come in handy in a zombie apocalypse survival situation. I'm gonna hang onto that sucker. Fixing it is definitely an option.
kc
--
Mike Garis
Jun 22, 2012, 2:35:36 PM6/22/12
to sa-hack...@googlegroups.com
Just a thought, if you do take the old TV apart and just in case your not aware, those old Flyback transformers can hold enough of a charge to hurt you, for a very long time. I know that has gotten people before, even though the TV may have been unplugged.
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