CB5-311 Headphone Socket Not Working

Have just acquired a second hand CB5-311. It's working OK except the headphone socket appears not to be working. No "SOUND DEVICE" options appear in the control area next to the volume slider. I can find no "Sound" options in the settings. I powerwashed the device when I got it, so it's at Factory Default Settings right now.
I've tried:
1. Three different types of headphones
2. The usual power off, insert, power on
3. I've dismantled, checked the socket for continuity and also the ribbon cable to the main PCB, all OK. Also cleaned the socket contacts. It's OK, I'm an electronics engineer!!

4, Tried using as Guest with the same results.
I'm running the latest Chrome version for this CB, Version 77.0.3865.35 (Official Build) dev (32-bit)
Short of buying a replacement socket assembly - if available - which I doubt is the cause - is there anything else I could try?
Thanks
Chas Large

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billsey

Yeah, you can ohm out the cable with the headphones connected to verify it's not a socket or cable issue. We don't have schematics for these systems, so it's tough to take it much further. It's likely in the audio circuit, but those are usually contained in the chipset and not using very many discrete components, so not terribly fixable.

CIL_ELECTRONICS

billsey said:

Yeah, you can ohm out the cable with the headphones connected to verify it's not a socket or cable issue. We don't have schematics for these systems, so it's tough to take it much further. It's likely in the audio circuit, but those are usually contained in the chipset and not using very many discrete components, so not terribly fixable.

Hi Billsey, yes did that, confirmed headphones and mic were connected and correct resistance. Injected a tone at the end of the ribbon to make sure I could hear sounds clearly from the phones.
I guess somehow the "chipset" is not recognising there is anything connected to the phones jack. Odd that a schematic is not available, how did they build them without that? or is it proprietary they don't want to give the joe public, even professional engineers like me??.
As there is no "Device Manager" like in Windo3s or Appl3 kit, there is no way of knowing if a device is even seen. I guess there may be some SW that could do it or even a command line but it's so locked down it's almost impossible. Shame really, a good little device that could have been donated to someone to make use of is now destined for the bottom spares drawer.

billsey

Yeah, ChromeOS can be a bit of a pain, just due to the 'ease of use' design, which hides so much from the user. There is a lot of info on the software and developer mode exposes some of that, so someone with the proper skills could probably see what's going on. You might try the USB recovery on a ChromeOS image to verify it's not just a corrupt build image that you are running. I've never had issues with headphones being recognized on any of my Chromebooks, and I've had several over the years. It's such a basic piece of functionality that I can't think of what could go wrong software-wise.

CIL_ELECTRONICS

billsey said:

Yeah, ChromeOS can be a bit of a pain, just due to the 'ease of use' design, which hides so much from the user. There is a lot of info on the software and developer mode exposes some of that, so someone with the proper skills could probably see what's going on. You might try the USB recovery on a ChromeOS image to verify it's not just a corrupt build image that you are running. I've never had issues with headphones being recognized on any of my Chromebooks, and I've had several over the years. It's such a basic piece of functionality that I can't think of what could go wrong software-wise.

Thanks Billsey. Tried a recovery, just the same. Guess the MOBO hardware is at fault but I'll strip it down and double check the connections and board, it may have had some damage as it was a scrapper with a smashed screen and top case which I replaced. I hate waste and given this is only just 6 years old, far too new to go to recycling.

billsey

Yeah, my oldest laptop still in use is dated 2006, running Windows 10 and acting as the controller for my CNC router.

CIL_ELECTRONICS

A small update: Discovered the system information list by entering chrome://system . in the browser window, this gives a list of all diagnostic data. Scrolling down to audio_diagnostics and clicking the Expand button you can see a list of connected devices.

Image: https://us.v-cdn.net/6029997/uploads/editor/44/50t82tvkm387.png

Plugging in the headphones and refreshing the list shows no change. Plugging in a USB sound card and refreshing shows the device

Image: https://us.v-cdn.net/6029997/uploads/editor/zv/13wmcmqj00ba.png

and also the Audio Settings option to the right of the volume slider also appears.
So it seems the system IS able to detect audio devices and the problem points to the headphone connection only.
Further digging in the Audio Thread Event Log under the diagnostics device list shows changes to BOOLEAN values, which indicates that when a device is connected, these values change and tell the system of the input. On the headphone circuit board and ribbon cable I recall there being a transistor which may be a discrete switch giving this boolean change of state. I'll investigate this further...

There is a post on Chromebook Unboxed here: https://www.youtube.com/watch?v=RSpRRoidezw showing the Audio Settings but interestingly, there are dozens of comments about how the headphones jack fails to identify a device plugged into it on many different devices, thus suggesting there is an inherent flaw in the design.

CIL_ELECTRONICS

Small Update:
Just discovered the ABOUT SYSTEM display you can get by entering Chrome://System in a browser window. This gives a list of the whole OS Diagnostic Data. Scrolling down to audio_diagnostics and clicking the Expand button, you can see all the connected audio devices:

Image: https://us.v-cdn.net/6029997/uploads/editor/05/p613fx8mb5w8.png

Plugging in the headphones and refreshing the display shows no change. Plugging in a USB sound card and refreshing shows the USB device:

Image: https://us.v-cdn.net/6029997/uploads/editor/uv/p0kxd5zistls.png

So it would seem the system IS detecting external audio devices. The Audio Settings icon also appears next to the volume slider.
Further delving into the Audio Thread Event Logs under the devices list, shows boolean value changes when devices are input.

I recall that on the headphone jack ribbon cable, there was a transistor, which may be a switch giving this logic change indication to the mobo and this may be what is at fault. I will investigate this further.

Interestingly, on the Chrome Unboxed YouTube channel, there is a video explaining about the Audio Settings and how they appear and what they do, see here: https://www.youtube.com/watch?v=RSpRRoidezw However, in the comments below, there are dozens of mentions of the headphone jack not working and or the Audio Settings not appearing on many different devices from different manufacturers. This leads to a conclusion that there is an inherent design flaw in the Chrome OS or Hardware. Mine is quite old but many of these comments are as recent as two months ago, suggesting there is still an issue with this.

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