Fxtec Pro1 X Crash - Audio 3.5mm Cable Unplugged / Plugged-In Causes LineageOS to Crash & Reboot

[own3mall 1]

Anyone else have this issue with their Pro1 X on stock / LineageOS?

When I plug in my aux cable from my car's radio to the 3.5mm jack on my phone, my Fxtec Pro1 X phone dies and reboots instantly. When Lineage boots back up with my cable still plugged into the port and car radio, the sound plays out of the phone's internal speakers and my car speakers via the radio connection. It should only play from my car speakers when the cable is plugged in.

When I disconnect the aux cable from the car's radio aux port after it crashed and rebooted, it instantly crashes and reboots again.

I tried using my computer headphones, and they don't have this issue. Maybe some kind of power sensitivity? My computer headphones don't crash the device when plugging / unplugging the connector, and the audio switches to the connected headphones appropriately.

Wondering if anyone else has experienced this?

[MonCon 123]

More of a workround than a fix, but this is what I use to get audio from my Prawn to my car.  

https://www.jaycar.co.nz/digitech-fm-transmitter-with-bluetooth-technology-and-usb/p/AR3140

Gives you a couple of USB sockets for charging as well.  

P.S.  I've not had the reboot problem myself, but I've only ever plugged in headphones via a '3 pin' plug (TRS).  

Is the cable that's causing the problem a TRS or TRRS?  

https://audiouniversityonline.com/ts-vs-trs-vs-trrs-audio-connectors/

Edited Saturday at 01:28 AM by MonCon

[EskeRahn 5,448]

Be aware that there - unfortunately, are TWO standards for the four-pinned 3.5mm with microphone, I do not know if the wrong type could cause this.
The OMTP and the CTIA. Now most devices (including Pro1/Pro1X) uses CTIA, some years back most (e.g the real Nokia) used OMTP.
OMTP is an a LOT more sensible standard BTW, having ground close to a plug housing that could be metal.

The easiest way to know if a given headset is CTIA or OMTP (if doc does not tell), is to measure the resistance between the right and left at the tip. Typically something like 320-340 Ω, then measure for he tip to the two others. The ground one will be around half (i.e typ. 160-170 Ω). The mic will typically be much higher.

NOTE, You can not expect a sensible measurement measuring this on a whole car system nor a Noise Canceling headset, as there are active components there, (including a battery)

As can be seen from the diagram, OMTP to CTIA converters are really simply, and you can find them for as low as £1 on e.g. AliExpress

[MonCon 123]

2 hours ago, EskeRahn said:

Be aware that there - unfortunately, are TWO standards for the four-pinned 3.5mm with microphone, I do not know if the wrong type could cause this.

As the saying goes:  "The great thing about standards is there are so many to choose from"

P.S. @EskeRahn Agree that a grounded 'sleeve' terminal at the base makes a lot of sense.  

Edited Saturday at 11:18 AM by MonCon

[claude0001 1,336]

On 10/19/2024 at 11:06 AM, EskeRahn said:

OMTP is an a LOT more sensible standard BTW, having ground close to a plug housing that could be metal.

On 10/19/2024 at 1:10 PM, MonCon said:

Agree that a grounded 'sleeve' terminal at the base makes a lot of sense.

AFAIK, the advantage of the CTIA standard is greater backwards compatibility. A CTIA headset can be plugged into a traditional (3-contact) stereo-jack socket and still work as an output-only stereo-headphone set (without mic function, obviously).

If an OMTP headset is plugged into such a socket, even the earphone function could not work, as there might be no connection of the speakers to common ground (the common ground of the socket contacts the MIC ring instead of GND).

Edited Sunday at 11:11 AM by claude0001

[EskeRahn 5,448]

6 hours ago, claude0001 said:

AFAIK, the advantage of the CTIA standard is greater backwards compatibility. A CTIA headset can be plugged into a traditional (3-contact) stereo-jack socket and still work as an output-only stereo-headphone set (without mic function, obviously).

Well it might, depending on where the contact for ground is in the old device. But certainly if plugged into a mono device, CTIA is very likely to work in Left channel.