On 02/09/2016 03:27 AM, gregz wrote:

[snip]

Anything switching current on a board can make sounds. Probably a magnetic
field created by current acting like speaker.

Greg


Around 1991, I had a TV (25-inch CRT) with a very audible horizontal
frequency. It was really annoying until I sold it to someone with
hearing loss.

--
Mark Lloyd
http://notstupid.us/

Never make a god of your religion

After serious thinking Mark Lloyd wrote :
On 02/09/2016 03:27 AM, gregz wrote:

[snip]

Anything switching current on a board can make sounds. Probably a magnetic
field created by current acting like speaker.

Greg


Around 1991, I had a TV (25-inch CRT) with a very audible horizontal
frequency. It was really annoying until I sold it to someone with hearing
loss.

It prolly had a bad audio tube or a bad cap.

On Wednesday, February 10, 2016 at 6:47:34 AM UTC-6, Eagle wrote:
After serious thinking Mark Lloyd wrote :
On 02/09/2016 03:27 AM, gregz wrote:

[snip]

Anything switching current on a board can make sounds. Probably a magnetic
field created by current acting like speaker.

Greg


Around 1991, I had a TV (25-inch CRT) with a very audible horizontal
frequency. It was really annoying until I sold it to someone with hearing
loss.

It prolly had a bad audio tube or a bad cap.

I'd suspect loose laminations in the horizontal output/flyback transformer which is operating at a frequency of +/- 15.65khz. A loose lamination could cause a vibration at a different frequency that would beat against the 15khz tone and cause a really irritating noise. Another problem could the horizontal scan frequency running at the wrong rate. I've seen all kinds of weird crap over the years when I was working on electronic equipment. O_o

[8~{} Uncle Flyback Monster

On Wednesday, February 10, 2016 at 4:32:23 PM UTC-6, Uncle Monster wrote:
On Wednesday, February 10, 2016 at 6:47:34 AM UTC-6, Eagle wrote:
After serious thinking Mark Lloyd wrote :
On 02/09/2016 03:27 AM, gregz wrote:

[snip]

Anything switching current on a board can make sounds. Probably a magnetic
field created by current acting like speaker.

Greg


Around 1991, I had a TV (25-inch CRT) with a very audible horizontal
frequency. It was really annoying until I sold it to someone with hearing
loss.

It prolly had a bad audio tube or a bad cap.

I'd suspect loose laminations in the horizontal output/flyback transformer which is operating at a frequency of +/- 15.65khz. A loose lamination could cause a vibration at a different frequency that would beat against the 15khz tone and cause a really irritating noise. Another problem could the horizontal scan frequency running at the wrong rate. I've seen all kinds of weird crap over the years when I was working on electronic equipment. O_o

[8~{} Uncle Flyback Monster

Really pertinent, thanks!