Coil whine

[olimex]

I would suggest two things

1. I can send you few coils and few step up converters if you want to solder and see if the problem will still exist

2. Send back the laptop so we can check here

[khumarahn]

Hi, thanks for the support!

I finally found a 22μH coil that should fit:
https://uk.rs-online.com/web/p/wire-wound-surface-mount-inductors/6920600

I ordered it and will try to replace. (I wish I did not do the superglue, argh!!!...)

On the other hand, if you want to try to understand what is happening, I will be happy to send the laptop to you. (Say, why the noise appears with one screen but not the other.)

[olimex]

send back the laptop so we will see how high is this sound
we experimented a lot on this and some sounds are not possible to be hear by some colleges but other colleges say they hear them so it's very subjective and the people who test the PCBs may have skip some boards with low noise

[khumarahn]

Good, I will post it to you, hopefully tomorrow. I this the address?

OLIMEX Ltd.
2 Pravda St.,
P.O.Box 237,
Plovdiv 4000 BULGARIA

In my case the sound is very distinct, and it seems to be not only in my imagination. My wife can hear it very well too, despite the new capacitors and the superglue.

[khumarahn]

Or should it be like this?

Olimex Ltd
Tzvetan Uzunov
2 Pravda Str
Plovdiv 4006
BULGARIA

[khumarahn]

Olimex people seem extremely busy... ping?

[LubOlimex]

The one at the about page is good enough: https://www.olimex.com/About/

Most delivery companies ignore the P.O. box anyway. It is helpful for our standard e-mail however, since Bulgaria post offices are a bit of a mess and if you don't have P.O. box and you missed the mailmain you might spend a lot of time searching for your mail around the town.

We don't keep close eye on the forums so if you are in a hurry try contacting Tsvetan over [email protected]

[khumarahn]

Good, I have sent it out. Hope it is not lost :-)

Just in case, I included my previous screen. It is shattered, but with it the coil is (and always has been) silent.

[khumarahn]

My package has been delivered on Friday in the evening, and today (Monday morning) I got an email from Olimex with a tracking number.

That is really fast! Though, I have not heard from Olimex, and I have no idea of what has been happening on their side. I hope that it helped and the source of the whine has been identified. If not, I have now a couple of coils to try as a replacement.

[LubOlimex]

Let us know if the whine persists.

[khumarahn]

ok :-) I am eager to find out what you have done!

[khumarahn]

The package quickly arrived, and I am very happy.

Olimex replaced the screen (this is my 3rd!). I could not tell if anything has been done to the mainboard, at least my stacked capacitors and the superglued coil are in place. But the new screen is FULL HD!!! And there is no audible noise now.

Also, they replaced the plastic screen bezel, where I broke a few clips. And included an 8gb flash card with a bootable image.

I am very grateful overall! Will try to understand how to make full hd work under gentoo (somehow the kernel boots into 1366x768).

[olimex]

Hi
LCD is not FHD for sure but you can try to run it in HD anyway!
The plastic is same we just placed the wires properly and now the plastic snaps well to the frame, the 8GB Flash SD card is probably forgotten by our people while testing the LCD for noise oh may...
anyway I'm glad we have happy customer
Tsvetan

[khumarahn]

It boots into full hd with the forgotten 8gb flash card :-) Well, I did not check the pixel dimension, but this is the resolution reported by xrandr. I am relieved that it is not full hd :-) It would have been a bit too much for the small screen, though interesting technically.

Looks like future Teres might have a full hd display?

[unclouded]

I took a trace of the VDC18V line with "Power Management Preferences", "On Battery Power", "Reduce backlight brightness" ticked:



This shows a 4.6 kHz cycle, which I guess is what we're hearing, and 1.74 Vpp with the stock C204 and C206.