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Old 20 May 2020, 01:00   #1
Signman
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1084 monitor high pitched sound

The monitor works well or so it appears. Only when I turned it on and my grandson grabbed his ears in obvious discomfort. So it is emitting a noise but what does it signify if the image is working fine?


Interestingly, there are hearing tests that you can find on the web and youtube to demonstrate how ones hearing has diminished mostly after 35 years of age. Or abuse I presume.
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Old 20 May 2020, 01:37   #2
Vypr
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A high pitched whine is usually the first sign of the flyback transformer starting to fail.
Replacing a flyback transformer is tricky at the best of times and not something that would be recommended if you've never worked with these type of high voltage circuits before because they can kill you if you're not careful.
What is likely to be happening is that the capacitors in the power circuit supplying the flyback are starting to go out of spec due to age so it owuld be worthwhile to look at getting them replaced.

Regarding the sound then yes, it is well known that younger people can hear higher frequency sounds than adults and a system was developed that used this as a deterrent to keep anti-social teenagers from gathering in some public places.

https://en.wikipedia.org/wiki/The_Mosquito
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Old 20 May 2020, 04:07   #3
AmigaHope
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All 15Khz monitors emit a whine at 15Khz. You can't get rid of it entirely. Some people lose the ability to hear it as they get older while other folks can still hear it.

People who grew up with them got used to it, but younger people who have never experienced it notice it right away. It could be that your monitor is operating perfectly normally and your grandson is just not used to the noise that kids from the 1950's-2000s just filtered out.

On the other hand if it's particularly loud a part could be going bad, but a failing flyback transformer usually generates a squeal at a much lower frequency that 15Khz (usually at a harmonic thereof). You can use a high performance audio analyzer (that comes with a very good mic) to see how loud the 15Khz noise is vs another 15Khz CRT.
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Old 20 May 2020, 12:39   #4
Juz400
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Quote:
Originally Posted by Signman View Post
Interestingly, there are hearing tests that you can find on the web and youtube to demonstrate how ones hearing has diminished mostly after 35 years of age. Or abuse I presume.



For testing from Subwoofers to age related hearing loss

https://www.szynalski.com/tone-generator/


Quote:
Originally Posted by AmigaHope View Post
All 15Khz monitors emit a whine at 15Khz. You can't get rid of it entirely. Some people lose the ability to hear it as they get older while other folks can still hear it.


One of the reasons for the Atari ST dominance in the Music Bizz, the Mono monitor has Horizontal frequency of 31Khz, way out of the `Audio spectrum`
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Old 20 May 2020, 13:40   #5
dreadnought
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Is that the same frequency some UK councils used to stop kids congregating in certain places?
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Old 20 May 2020, 21:30   #6
Nobby_UK
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Yup, more or less (17.4 kHz)
see the Wiki Linky Vypr posted:
https://en.wikipedia.org/wiki/The_Mosquito
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