01-17-2020, 12:31 PM
(01-17-2020, 09:39 AM)cheburashka Wrote: Just tried one more thing. I have my wireless mouse dongle plugged in, high pitched noise is there. I plug my phone in to the other USB port and it starts charging and the high pitched noise disappears. Take out the charging phone and it's back.
Seems to be some kind of input/output unbalance or something (okay maybe I just said something really stupid, but I'm pretty much a-technical).
Other posters have reported the noise going away by increasing the screen brightness. As noted, things such as card readers without cards, and mice, do not draw much current. So it seems to be happening within a range of current draw — above or below a certain load. Which leads me to suspect it's the resonance of a band reject filter where an inductor is oscillating. Perhaps someone could find the specific inductor by muting it with a gloved finger, using a can of freeze-it, or some other method, then smothering it with epoxy so it doesn't vibrate.
