Can't end phone calls because of black screen

[dixijo]

Hi,
Often when trying to make a call my Fairphone has an annoying error.
When the call is made (i.e to a mailbox) the screens blackens.
Then I am not able to end the call anymore. Trying to activate the phone again (for example shortly pushing the power button) the screen immidiatly blackens again - so fast its impossible to hit the red button to end the call.
Sometimes I am able to end the call after a lot of tries but occasionaly I have to reboot the phone or have or wait till the other side ends the call.
Any ideas about the problem?
Best regards
Johannes

[Stefan]

You can set the power button to end calls in Settings > Accessibility > Power button ends call as a workaround.

[dixijo]

Thanks a lot. Your workaround should help till the cause of the problem is found.

[aljoscha]

Same problem here. Having already used the power button method before. But while calling I can’t e.g. activate the speakers or type numbers for hotlines.

[dixijo]

Yes, thats also part of my problem and not solved with the workaround. When stuck in a hotline and forced to press numbers, I can’t go on.

[Johannes]

@dixijo

Any ideas about the problem?

Sounds like a problem with the proximity sensor - it’s located just left of the grill for speaker that you listen to when making normal phone calls. There may be a test function in testing mode (not sure) or you can use an app like CPU-Z to read out the sensors. In the latter the value should alternate between 0 when you put your finger over the sensor, to 1 when you remove it (it may not show any value until covered at least once). If it stays stuck on 0, it could mean anything from something obstructing the sensor from the outside of the glass (screen protector, scratches, smudges, stickers) or between the glass and the sensor (if dust somehow got into the phone) to a defective sensor (which may be a warranty case - you’d need to ask Fairphone support).

[dixijo]

Thanks, I just installed CPU-Z. The sensor seems to work.

I also found this thread:

Near field (proximity) sensor reacts slowly/hangs up calls

The current configuration of the near field sensor ( @Chris_R, maybe you could change the topic to be more clearly that this is about, so others who have no idea what that sensor is are able to find it?) is a problem for me as well. I often find myself in Time Zone settings or Calendar when finishing calls and i very often hang up by accident. Interestingly, I had the same problem with other phones like the Nokia N8 or a cheaper Acer Android Smartphone (which is powered by an chipset of the sa…

It seems to be a quite common issue with no real solution at hands yet.

[Martijn]

I also had a problem with my proximity sensor, and went to the custumer service for it.
This was their response:

We’ve just released a
new software update, which is called Fairphone
2 OS 1.5.1 (make
sure your phone is up-to-date), and it is a first step towards fixing your
issue.

In this update, there is a tool to calibrate the proximity sensor of your
Fairphone 2. In other words, the update is not solving the issue itself but
provides a tool to improve it.

Please follow these steps to recalibrate your proximity sensor:

Dial the following code
where you normally enter phone numbers when you want to make a call: ##8765##; the calibration app
will start (it can take a minute the first time);

Cover the upper-left
area of the display (use an opaque object);

Press the “Read
sensor data” button; the app will display “Reading…” and then
go to the next screen;

Uncover the upper-left
area of the screen (take the covering object away);

Press the “Read
sensor data” button; the app will display “Reading…” and then
go to the next screen;

The final screen will
display “Cal Success. press Exit to reboot to finish cal process”.
This means that the sensor calibration was successful. Now restart your phone
by pressing the “Exit” button.

The calibration app is harmless for the device, it will only set new
calibration values for the sensor.

The following error messages can appear:

·
Block value < 230, please ensure you have blocked sensor
before reading data

·
Make sure you covered
the upper-left part of the display left of the ear speaker at step 2. You can
also cover the whole upper part of the phone.

·
Start from step 1
again.

·
Unblock value is too high, please clean screen and cal again

·
Make sure you removed
the covering object at step 4.

·
If the issue persists,
make sure the display is clean on the outside and then also on the inside as
described in our
troubleshooting guide.

·
Start from step 1
again.

We will publish a new software update by the end of July with an app which is
easier to use. We assumed you would not want to wait two more weeks so we are
offering you this interim solution.

It works fine for me now, maybe you can do something with this.

[freibadschwimmer]

Yes, so it it described here as well:

FP2 Screen can't be reactivated during/after calls - See first post for Workarounds

Solution: Please follow the official troubleshooting tool.

archived text

Besides a badly calibrated sensor the next most common reason for this issue is dust between the proximity sensor and the screen. For more info check <a href="https://forum.fairphone.com/t/fp2-screen-cant-be-reactivated-during-after-calls-see-first-post-for-workarounds/11874/148?u=paulakreuzer">this post</a>. Cleaning tips: Clean the screen of your phone, especially the part where the proximity sensor…

But note that this thread here relates to FP1, the bug fix with recalibrating the proximity sensor only works for FP2!

[dixijo]

Thanks a lot for your reply. Unfortunatly this only works with a FP2 and I have got a first edition.
Hopefully the developers will implant this tool in the september update for the FP1.

[Stefan]

@dixijo

Hopefully the developers will implant this tool in the september update for the FP1.

This would require a lot of work because of the entirely different hardware of the FP1.

However, I might have a solution for you: Check, if the little rubber part securing the proximity sensor inside your FP1 is placed correctly. (You can see it in step 28 of the corresponding iFixit-tutorial). If it covers the proximity sensor, the screen stays black, when you move the phone away from your head.

[dixijo]

Thanks a lot. I will give this a try. My screen broke and I replaced it. Could be the rubber part was moved then.

[Regine]

Same is true for me: When the call is made (i.e to a mailbox) the screens blackens.

[MegaJoule]

I have the same problem after having had replaced my touchscreen of FP1U. However I am not sure whether it is really related to the sensor as the screen also turns black when I don’t put the phone to my ear and don’t touch or move it at all after dialing or picking up.

[paulakreuzer]

@MegaJoule

However I am not sure whether it is really related to the sensor as the screen also turns black when I don’t put the phone to my ear and don’t touch or move it at all after dialing or picking up.

That’s the thing with a malfunctioning proximity sensor. Just a little dirt behind or a smear on the glass can be enough for the sensor to believe it is covered and the screen becomes dark.