[Guide] Replacing a broken fingerprint sensor - Xiaomi Redmi 4X Guides, News, & Discussion

This post is just for reference, in case anyone needs pictures of original parts and a small guide on how to replace the fingerprint sensor.
This video (not mine) shows the process as well, on a Redmi 4 (non-X), except you don't need a screwdriver for the 4X. And there's no fp sensor test in the 4X MIUI engineer test app.
I recently bought a Redmi 4X with a faulty fingerprint sensor.
I noticed in both MIUI11 and LineageOS:
- I was not asked to add a fingerprint during initial setup
- There are no fingerprint settings for lockscreen security (only PIN, pattern, swipe). If you try to search in settings for "finger" and tap on the result, the page will be empty/blank.
I tried some software tricks like deleting files, but that did not help here. On the phone itself, the fp sensor had a tiny dent/hole in it (can be seen on the pictures), less than 1mm in size, which revealed a bit of silver colour under the black surface. Looks like it hit some sharp object. I'm not entirely sure if that caused it to fail though.
So I bought a replacement (less than $10, pictures attached). After opening the phone with plastic tools, removing the old fp sensor ribbon cable from the motherboard, just push the old sensor out of the case through the hole with moderate force. It is glued in place with some sort of foam, clean it off with some tweezers and isoprop alcohol. I installed the new sensor with some B-7000 glue (if you make any mistakes with B-7000, just wipe it off before it dries with a qtip and isoprop alcohol and try again).
My replacement seems to be the common one sold on Aliexpress and elsewhere, it works fine and appears to be fpc (persist.sys.fp.goodix is 0).
Text on original Xiaomi fp sensor ribbon cable (ribbon cable has a black colour):
F3208FD RA0
F 171501
Text on replacement (ribbon cable has copper/bronze colour):
[icon]-film 0251-00 V4HX-1718

Related

Correct way to turn off proximity sensor

I'm visiting my parents and my mother's Z3 Compact has issue that screen goes black when call is made. It turned out proximity sensor reports always active on state. It seems to work when I push the top-left part of screen but I have no experience with fixing HW issues so I don't want to open the phone.
Instead I would be happy if it was possible to disable the proximity sensor altogether for now. Phone is bought as used and it seems to have bootloader unlocked so it wouldn't probably be a big deal to root it if that would help with fixing the issue. Any suggestions what to do? I tried some programs like Proximity Screen Off Lite which some people mentioned had done it for them but it seemed not to help me with this issue.
Hi. Proximity issue is result of peeling off screen from frame. Just take some epoxy glue and apply a little to the gab in the corner between frame and screen. Just watch out to not apply glue on proximity sensor, but only on the frame. After that take some clip to press it and left it for 24 hours to make sure glue get dry. Thats all. Of course You can also take apart whole phone and change whole glue adhesive under the screen but this one is quite harder than just apply some glue in gap between screen and frame.

Wierd issue with Nokia 8.

I only got this phone couple of days back and I am having a strange problem.
After installing a screen guard, touch stops working when phone is lying on flat surface. Once I lift the phone, touch starts working again. This happens regardless of the phone is plugged or not in a power socket.
Removing screen guard resolves this issue. However, I installed three different screen guards of glass, plastic and rubber types and with each type touch stops working on a flat surface.
I also did a factory reset but it didn't help. I tried with case on and off but the problem still persists.
At this point I am clueless how to resolve this issue as the phone doesn't seem to be defective as touch works flawlessly without a screen guard.
Same here!
With glass screen protector I have this issue... Can't really use it while device lying on a table.
Hi... Same here also... I thought the screen problem but not even lying on the table but when in charging lying on the table also can't touch... And sometimes it's stuck when to touch... My nokia 6 i think also like that... Maybe the screen curve is??
I have screen protector bought from Taobao, no such problem on my Nokia 8, TA-1004.
The screen protector is not glass type, but looks like plastic type.
Another strange observation: If I plug headphone jack when the phone is lying on flat surface, touch starts working again.
I suspect this entire thing has to do with metal/glass body of the phone and static electricity generated or magnetic field around touch panel.
I don't have much knowledge on this type of scientific stuff so I am not sure what the problem is.
It's the cheap glass protector and its glue that is messing up the touch screen.
references said:
It's the cheap glass protector and its glue that is messing up the touch screen.
Click to expand...
Click to collapse
I thought so. But what about headphone jack fixing touch issues with screen protector on?
Also, I have used similar quality screen guards on Moto and Huawei phones at my home and they don't have this issue.
Nitg16 said:
I thought so. But what about headphone jack fixing touch issues with screen protector on?
Also, I have used similar quality screen guards on Moto and Huawei phones at my home and they don't have this issue.
Click to expand...
Click to collapse
Are you connecting it to headphones or speakers?
Maybe the capacitive buttons doesn't like the glue and messes up everything? You could try enabling these in the Developer Options: Show taps & Pointer location. Let me know what is happening
references said:
Are you connecting it to headphones or speakers?
Maybe the capacitive buttons doesn't like the glue and messes up everything? You could try enabling these in the Developer Options: Show taps & Pointer location. Let me know what is happening
Click to expand...
Click to collapse
Headphones.
Enabled taps and pointer location. When phone is not touching a flat surface everything works fine. A curve is drawn on screen showing various gestures and a circle is drawn to show taps.
When lying on flat surface, if I use any touch gestures (e.g. scrolling) curve is drawn once in 5-6 attempts. Same with taps, circles appear only once in a while.
It is all very erratic. When I repeatedely try to tap anything, I receive ghost touces at a different part of screen.
Just noticed that I don't need headphone jack to fix touch. Blocking 3.5 mm port with one finger also works. This is truly getting weird.
Have you shown it to the Service Centre? Do they have any theories?
Sent from my Pixel 2 XL using XDA-Developers Legacy app
No, since the phone works perfectly without screen guard, I think service center guys will simply tell me to use it without a screen guard.
But I will indeed show them this problem after few days, though I am not sure they will understand or will be helpful in this regard.
I think I am reaching somewhere. The antenna reception at the top might be messing with touch.
What I have observed that touching the top of the phone or keeping any object or my hand one inch away from top of the phone fixes touch issues.
If I remove the object or move it farther than one inch, touch becomes messy again.
If I put little pressure on bottom chin of the phone, the top of the phone raises a bit so that the top antenna is not close to flat surface any more. This also fixes touch issues. Lowering top part of the phone brings back touch issues.
Anyone else with this issue can test this?
This video exactly describes my issue:
I found that many phones had these issues in past including oneplus, lg, sony and galaxy phones. Everywhere it was mentioned that it is a grounding issue which is unfortunately a hardware detect.
My phone is fortunately within replacement window. So I will contact the seller and request for a replacement.
I was thinking about the grounding, but when you mentioned you used headphones i thought it couldn't be the case.
Keep us updated if you get it replaced.
Just received the replacement. Same problem on the new one
I don't know what to do now. No other phones in my family have this problem and that includes $200 budget devices. This is flagship and much more costly.
I will just summarize different cases in which the touch issues on a flat surface gets fixed on my device:
- Inserting headphone jack (with screen gaurd applied on display).
- Inserting charging cable (with screen guard applied on display).
- Touching any part of the phone with finger including blocking the headphone jack (with screen guard applied).
- Removing the screen guard.
I am tired of this sh*t. I have tried all things possible to fix it. I have also wasted money on 6 different screen guards to fix this issue.
Some guys on galaxy s8 forums mentioned that modern curved phones uses a touchscreen placement mechanism different than traditional smartphones (they were also having the same problem).
There were two possible solutions mentioned:
Find a screen guard that has glue all over, not just around the edges or at dots. Which means that screen guard should stick to the screen 100% flat without any gap, air or bubbles.
Second solution was to use a flip cover to protect the screen and no screen guard.
I will go with second solution and buy a flip cover. I simply have no energy left to hunt for screen guards that work properly on Nokia 8. Not to say that you will never know if it works or not unless you purchase it and stick on your phone.
Hi, I'm writing from Italy and I've the same problem, exactly the same problem, solvable with the same solutions you have proposed: remove the protective film (a glass screen guard in my case).
I'm noticing that the touch screen works perfectly with the protective film only if the phone is connected via USB cable to the battery charger or to the pc.

[FIX] [REPAIR] XIAOMI Redmi Note 7 Proximity Sensor fix after screen replacement

So i replaced the screen glass and digitizer and watched a few YouTube videos of the teardown of the redmi note 7 and soon realized my proximity sensor didnt work after i changed the screen and screen frame . Upon further investigation i noticed most of the youtube videos DID NOT point out some of the extra hardware that needed to be changed as well and as a result my proximity sensor did not work. So if you have previously replaced parts on or repaired your XIAOMI REDMI NOTE 7 and notice a few things arent working here are few things that you may have forgotten to swap and replace. After i swapped the pieces over my proximity sensor worked again. Note that the blue tape is there to PREVENT DUST from hitting the sensor and glass, so only remove the tape when you are ready to replace.
I was wondering after the screen replacement, how is the latency on the edge of the screens? Can you compare it please? My phone is brand new but because of this latency i want to replace the screen and digitizer with non official one.
Hi. I'm exactly in this case. where did you buy the the extra hardware that needed to be changed?

Disabling Proximity sensor - Nokia 7 plus

Hi All,
I am using Nokia 7 plus for past 2 years. Andorid 10 with Nov security patch. Recently, my proximity sensor stopped working and I am not able to use phone any more (due to black screen during calls). I even root my phone and installed edxposed framework for disabling proximity sensor but no luck. Even sensor disabler not working for me. Any suggestions would be much helpful as I want to use this phone badly
I have same problem (stop working after lcd replace), try more solution, but at end i find one "working"... In Developer options enable QuckSettingsDeveloperTiles/SensorOff, this add Sensor tile to top pulldown QuckSettings menu, before call must you manually enable it, after call disable (because sensor off disable all sensors and also camera ;-)
k3dar7 said:
I have same problem (stop working after lcd replace), try more solution, but at end i find one "working"... In Developer options enable QuckSettingsDeveloperTiles/SensorOff, this add Sensor tile to top pulldown QuckSettings menu, before call must you manually enable it, after call disable (because sensor off disable all sensors and also camera ;-)
Click to expand...
Click to collapse
Yeah, I have been using it. Problematic when attending calls in Skype which wont work unless you switch again. Thanks anyway
In my experience, proximity sensors don't stop working, they just work all the time! Often there's a small rubber gasket which separates the UV LED from the sensor. Can be lost when replacing a screen - I did this myself on a Moto G. Screen would go black in a call and couldn't be unlocked. I found the gasket on the floor, replaced it and this fixed the problem. Replaced the screen on a Nokia 7 Plus recently, same problem. I couldn't find a missing gasket this time, but glued a small piece of rubber between sensor and LED and this fixed the issue. Had to experiment with the size of the rubber piece to get it working properly. I think some of the UV light bounces off the back of the screen and is picked up by the sensor , if this piece is missing. My $0.02 worth...
Guys, I am frustrated with proximity sensor of my Nokia 7 Plus, as soon as I call, screen goes black.
I could stop it by enabling Developer Mode and disabling sensors, but this disables all sensors not proximity, and my camera stopped working.
Can I just remove it from mother board? any way to disable only proximity sensor?
Thanks in advance.
MrNams said:
Guys, I am frustrated with proximity sensor of my Nokia 7 Plus, as soon as I call, screen goes black.
I could stop it by enabling Developer Mode and disabling sensors, but this disables all sensors not proximity, and my camera stopped working.
Can I just remove it from mother board? any way to disable only proximity sensor?
Thanks in advance.
Click to expand...
Click to collapse
If you've had the screen replaced, I think the rubber gasket separating the IR LED and sensor has been lost. Seems to be a common cause of this kind of problem. Cheers
Gastrocnemius said:
If you've had the screen replaced, I think the rubber gasket separating the IR LED and sensor has been lost. Seems to be a common cause of this kind of problem. Cheers
Click to expand...
Click to collapse
Many thanks for quick reply.
Yes, I replaced screen. I don't remember about rubber gasket, but now i have to open scree and fix it.
Can we just remove proximity sensor from board? What functions get affected?
MrNams said:
Many thanks for quick reply.
Yes, I replaced screen. I don't remember about rubber gasket, but now i have to open scree and fix it.
Can we just remove proximity sensor from board? What functions get affected?
Click to expand...
Click to collapse
I guess just the screen turning off during a call. But removing it may damage some other component, I guess. I also wonder if the screen stays off or on permanently if the sensor is removed. If you're taking the screen off anyway you could just try my fix of glueing a small piece of plastic or rubber between the sender and receiver, has worked for me and is still working. But this is just my opinion, all the best in whatever you decide to do. Cheers
Gastrocnemius said:
If you've had the screen replaced, I think the rubber gasket separating the IR LED and sensor has been lost. Seems to be a common cause of this kind of problem. Cheers
Click to expand...
Click to collapse
Yes, I replaced screen. I don't remember about rubber gasket, but now i have to open scree and fix it.
Can we just remove proximity sensor from board? What functions get affected?
Gastrocnemius said:
I guess just the screen turning off during a call. But removing it may damage some other component, I guess. I also wonder if the screen stays off or on permanently if the sensor is removed. If you're taking the screen off anyway you could just try my fix of glueing a small piece of plastic or rubber between the sender and receiver, has worked for me and is still working. But this is just my opinion, all the best in whatever you decide to do. Cheers
Click to expand...
Click to collapse
Ok Thanks, I shall try it.
One more question
Is there a way to disable only proximity sensor through OS/App? This will save my effort to remove it from board and possible damage to board.
Am working on another 7 Plus which has the gasket fitted to the proximity sensor and took some pictures so y'all can see what I'm talking about. First picture is of the gasket, second is the sensor without the gasket. Cheers
Just checked in to this forum for give Gastrocnemius a big "Thank you"!
We have a Nokia 7 Plus with the "normal" USB connection issue.
Send to repair to an independent repair station (so not Nokia), who offered a good price.
When it came back it looked fine, charging and fast charging was possible, we have been happy.
Until the first call... Black screen with dialing.
A short search showed: many problems after an update, looked like software related issue with no solution.
Shortly after the new USB connection was faulty again.
So the phone went into a drawer and replaced with a new Nokia.
Now my old Redmi 4 is too old and some for me important apps will not work with the "old" android.
I remembered the Nokia 7 plus and started to repair the USB board, also as a trial if i can handle mobile phone repairs for myself. Well, cheap USB board found, change successful... not! Broke the Display (stayed black after assembly, board from display got hot, probably cable broken).
Ok next step, new display, screen works and and charging repaired on first view.
Function check: black screen during call. Tried several proximity fix tools without success.
The app Phone Check clearly identifies as proximity sensor as "close" / near, no change.
The change to far came only when the display was way to the side. So, the sensor is working, but the function close far is not working.
After weeks I discovered this fred! Gasket? Which gasket! There is no gasket! Check with several videos on YT, yes, gasket identified!
So I tried the mentioned fix rubber band but was not able to get it working.
Then I looked for a gasket online and found one available for the Nokia 2 / TA 1007 on EBAY for a couple of Euros and ordered it for giving it a try.
I just assembled the gasket.... the 7 plus no works like new!
So I'm assuming that during the first USB-board change the gasket got lost and the check by the repair company was only performed for the charging and no more checks for the rest or they didn't care (ASUMING!)
Long story short:
If the gasket is missing you can use the one from the TA-1007!
It does look a little bit different than the above gasket but mine worked. No further assembly from the phone is required, just slip it over the sensor (make sure that the big hole is left, seen as microphone is up and sensor is up left [don't know how to describe better]).
Thanks again for the hind to the missing gasket.
Best regards from Munich,
Thorsten
(typos corrected)
Blackboie said:
Just checked in to this forum for give Gastrocnemius a big "Thank you"!
We have a Nokia 7 Plus with the "normal" USB connection issue.
Send to repair to an idependent repair station (so not Nokia), who offered a good price.
When it came back it looked fine, charging and fast charing was possible, we have been happy.
Until the first call... Black screen with dialing.
A short search showed: many problems after an update, looked like softwrae related issue with no sollution.
Shortly after the new USB connection was faulty again.
So the phone went into a drawer and replaced with a new Nokia.
Now my old redmi 4 is to old and some important apps wil not work with the "old" android.
I remembered the Nokia 7 plus and started to repair the USB board, also as a trial if i can handle mobile phone repairs for myself. Well, cheap USB board found, change sucsessful... not! Broke the Display (stayed black after assembly, board from display got hot, probably cable broken).
Ok next step, new display, yes, phone and charging repaired.
Funktion check: black screen during call. Tried proximity fix tools without sucess.
The app Phone Check clearly identifies as proximity sensor as "close" / near, no change.
The change to far came when the display was way to the side. So the sensor is working, but the function close far is not working.
After weeks I discovered this fred! Gasket? Which gasket! There is no gasket! Check with several videos on YT, yes, gasket identified!
So I tried the mentioned fix rubber band but was not able to get it working.
Than I looked for a gasket online and found one available for the Nokia 2 / TA 1007 on EBAY for a couple of Euros and orderet it for giving it a try.
I just assembled the gasket.... the 7 plus no works like new!
So I'm assuming that during the first USB-board change the gasket got lost and the check by the repair company was only performed for the charging and no more checks for the rest or they didn't care (ASUMING!)
Long story short:
If the gasket is missing you can use the one from the TA-1007!
It does look a little bit different than the above gasket but mine worked. No further assembly from the phone is required, just slip it over the sensor (make sure that the big hole is left, seen as microphone is up and sensor is up left [don't know how to discribe better]).
Thanks again for the hind to the missing gasket.
Best regards from Munich,
Thorsten
Click to expand...
Click to collapse
Glad to hear it worked for you Thorsten!

Mi 9T Pro has bad ghost touch issue after screen/digitiser change

Hi everyone!
The phone has bad ghost touch issue after a new screen was installed. And I am not able to pin point the cause.
Sometimes the issue is very bad with ghost touches more frequent with a ghost touches repeating under 1 second, sometimes the touches are much more rare. After the first installation I took the screen off and just reconnected without installing it and it had no ghost touch issues at the time but the issue returned when it was assembled.
Do you have any similar experience or idea what contact/connector/plug might cause the problem?
Thank you in advance!
I have tried to reinstall a full factory ROM but that did not help. The issue exists even on TWRP screen so I guess it must be a hardware problem.
Ghosting is a known issue with this phone. You can find many different solutions, but nearly all of them is about insulation.
The first method: Try to install some insulation under the main speaker. But be aware, if you put too much insulation there, you'll be unable to put back that plastic piece correctly.
The second method: Put some insulation onto the back of the screen like this.
The next two method are my own solutions to this problem, these fixed my ghost touch issues on my second Mi 9T Pro.
Fully assemble your phone, then place it on a completely flat surface with the screen pointing downwards. Now try and push each corner of the phone. It it remains stable, then move to the next idea. But if you feel that the phone is bent, then take a regular hair dryer, heat the phone with it's lowest mode everywhere for 5-10 minutes, then place something heavy on the back of the phone (like an older notebook or a desktop hard drive) until it cools down. Repeat the process if needed, but be careful, too much heat can cause other issues if you're not careful enough.
And the final solution: Remove the glass backplate, and the plastic cover with the main speaker. Then take a look at the bottom left corner of the phone, where you should see a hole in the frame, and some black insulation tape in this cutted hole. Remove that piece of tape, and gently push that orange-yellow circuit against the back of the screen. If it moves too much, you can try to wedge it with a piece of plastic.
I hope one of these solutions will help you to fix your screen. An extra tip for you: If any of these solutions work when the phone is fully assembled, don't try anything else, otherwise you'll risking to make the problem reappear.
Szatyor said:
take a regular hair dryer, heat the phone with it's lowest mode everywhere for 5-10 minutes
Click to expand...
Click to collapse
I wouldn't recommend hairdryer as without being careful it's easy to damage parts.
Someone, maybe IFIXIT came up with nice suggestion to use hand warmer and heat it with microwave. It's almost ideal solution, as it's not overheating and applies heat everywhere.
Disable three finger screenshots and ghost touch issues will be gone on 5 point touch displays(replacement)
MIUI 12 Fingerprint Unlock defective
After upgrading to MIUI 12 Global OTA yesterday, fingerprint unlock stopped working. When I select fingerprint unlock in settings to switch it on and enter my PIN, phone goes dark and restarts (MIUI splash screen). Any suggestions? Phone is stock...
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