[Q] Low/dim backlight after screen replacement - Xperia Z2 Q&A, Help & Troubleshooting

Hey there!
I'm currently trying to repair an Xperia Z2 that had water enter its chassis. The initial fault was that the backlight was completely non-functional with the screen still working as you could make out stuff when shining a bright light on the display. I read that this can be due to a blown fuse on the board, but before attempting to solder, I decided to get a replacement screen first.
The replacement screen has the backlight working, but it's very dim as if it was fixed to the lowest brightness setting. Naturally, I tried changing that in the Android settings, but to no avail. Various combinations of settings like turning the adaptive brightness on or off also does nothing. I tried a factory reset as well, but the issue persists.
Could this still be due to a bad fuse? At the very least, the old screen definitely had a defect since the new one has the backlight working at least somewhat. I'd be surprised though if there was a fuse solely responsible for letting you control the backlight brightness.
I checked one of the fuses commonly suggested to be responsible, as explained in this post. It's still conducting electricity though, so I doubt that's it. The other fuse is near the CPU below the heatsink, but I had trouble testing that since it's covered with some non-conducting substance like a resin of some sort.
What do you think? Any help is appreciated!

Hi did you ever find out what the problem was?, because i have the extact same problem with mine after water came into it and i replaced the screen.
any info could be of help

Related

[Q] light sensor broken?

Hi guys,
Ill start with saying that my english is veryy bad
But my problem is:
I quess my light sensor on my hd2 is almost defect.
why?
When i start a call (or got an incoming call) the screen turns black
(as its suppose to be when you hold it to your ear)
But it turns black all the time, no matter how i hold it.
So i did a quick test, i called a number, and took a very bright light (100w) just next to the sensor. and after that, it doenst turn black for the first time!
So the sensor isnt working correctly anymore?
It is since my telephone has gone back to the shop for a new screen.
Can i make it better with software? Cause it works.. But only with a very bright light.... Or do i need to get back to the shop?
thnx
try a soft reboot and then if needed a hard reboot/factory reset. don't forget to back up the phone first as it wipes the phone
Sorry, i was forgotten to say:
Ive tried different roms, and even Android. Results are always the same!
That is an odd problem. Especially since the ambient light sensor is not what is used to black out the screen during calls. That would be the proximity sensor.
If you look very carefully just to the left of the speaker at the top of the phone you will see the proximity sensor. Do you have a case on your phone that may be blocking/interfering with this sensor? Do you hold your phone in a way that your fingers or hand may be close to this sensor?
Another thing to try is put the call on speaker phone, this should disable the proximity sensor and keep the screen on. If it does not then you may potentially have a hardware issue.
I haven't got something blocking the sensor. But because my screen was broken, they placed another one. (And since then it happend)
Ok, i did some tests..
I cleaned the screen very proper. And i was sure there was no spat of dust or whatever. so i called again.. And it worked properly!
But.. When i put my finger on the sensor.. (So its not 100% clean anymore) it turns black again. So its veeeeery sensitive..
When i turn on the speaker.. It doesnt turn black..
So conclusion:
It turns back way to fast. Only when the screen is 100% clean, and there is enough light in the room.. It works properly..
Aren't there any settings for windows or android to change the sensitivity? Cause this is very annoying..
Aren't there any settings for windows or android to change the sensitivity? Cause this is very annoying..
Click to expand...
Click to collapse
Not that I'm aware of. It sounds like they didn't do a proper job of replacing the screen. The ammount of light in the room should have no impact on the screen turning on/off. Also, my screen is often quite filthy and I've never had that trip the proximity sensor. It is possible that the sensor was moved or misaligned during the repair.

GT-i9300 Display Issue

This may seem a bit strange, but I have an old i9300 that has run into a bit of an issue. The device itself runs fine, boots CM12.1 (Unofficial port, I know), but the issue is that sometimes the LCD Display goes to a point where it's unreadable. It'll look fine on a normal startup (Displays the Samsung Galaxy S3 GT-i9300 Logo), but then the display dims after that. While in Download Mode, it'll do the same thing. Attempting to reboot into recovery with this display dimmed causes a bootloop. I know that the AMOLEDs don't have backlights, but every so often, the backlight (I know that's not what it's called), will function properly. It's a very strange conundrum. Could it be that either something is loose, or the AMOLED is going out?
There is no backlight on AMOLED, each pixel illuminates individually so your problem is with the screen driver or connections. Water damage can cause the symptoms you describe, first step is to strip down the phone and check the connections.
boomboomer said:
There is no backlight on AMOLED, each pixel illuminates individually so your problem is with the screen driver or connections. Water damage can cause the symptoms you describe, first step is to strip down the phone and check the connections.
Click to expand...
Click to collapse
I gave it a thorough strip-down and checked for signs of water damage, but there wasn't any water damage to be found. I checked the strips that indicate water damage and they were still white. I also checked the connections, reseated them firmly and restarted. I haven't had the issue again since, but it's not a consistent issue, it pops up every so often.

LCD Backlight is on but there's no video output

Hello!
My phone fell from a high place some weeks ago and the screen shattered. Touch was unresponsive, clicking everywehere, but LCD was fine, i could see everything on screen normally.
Ordered a new screen. Changed it, but when I turned it on, only backlight of the LCD was visible, but it was displaying nothing. I thought it was a defective screen (either way, it was, lots of stuck pixels), sent it back and bought another from the same seller. When I changed it and turned it on, again, no video output, lcd would light on but woundn't display nothing on screen. Googled a bit, found out it could be a defective fuse on the motherboard, and that soldering it again would solve. I know nothing about this kind of stuff, so I picked up a tweezers and apllied a little force on every fuse, because I thougth that way I could try to solve it. Well, it worked, kinda. I put the screen above that blue plastic glue only for testing, and it worked, I felt reliefed for seeing sony boot logo again. Figuring out it had worked, i took out the screen, took out the blue plastic, and glued the screen back on. For my surprise, it had the same problem as before, and it doesn't matter what I do now, it wont work anymore, only displays a black backlight with no video.
Could anyone help me out with this? Give me a hint of why it worked once but not anymore. Could it be there's really a defective fuse, or it was just a coincidence that it worked after it had force apllied? Also, the Screen flex is kinda loose, it keeps coming off all the time, and it's really hard to plug it to the LCD sometimes, is it supposed to be like that, or could it be the culprit? Also, touch is working normally, i can't see nothing on screen but i can click and feel it vibrating.
It's kind of a big text, but that's the way I could explain it. Sorry for the bad english, it's not my native language.
And thanks in advance if anyone can help!

Main screen display is very Dim even when the brightness is adjusted to max

Display backlight is not working of a sudden even when i keep the brightness at max and second screen is working but the display is not working with good backlight ! I just took the phone from my pocket and what i seen is the display is dim ! Display is so dim even when the brightness is kept at full and i dont know how this happenned and someone tell me the way to solve this problem ! Screen is very dim even when i adjusted the brightness level at max and i even tried formatting phone but the issue remained same
Hi this also just happened to me. Image is working but no brightness in screen except some bright ess in top right corner. Phone overheated a couple kf times and shutdown after this initially happened and consumed 2 full batter chages in minutes. Now the heat and battery problem is gone but screen still dark. Any ideas
Hi guys!
I`m having the very same problem. Back light of the main screen is gone, and it doesn`t matter how I adjust it, it is always dark.
Have you guys solved your problem already? Any ideas?
Marcos
Having the same issue as of yesterday, been Googling possible reasons and it seems the 'backlight controller' has malfunctioned and the entire screen needs replacing (allegedly). Considering a new screen costs almost as much as the V10 itself on ebay these days I'm going to be trying to take mine apart to see if an easier fix is possible, it is more than likely there isn't, but I at least have to try. Let me know if any of you guys have any luck in repairing your phones
Revilo61 said:
Having the same issue as of yesterday, been Googling possible reasons and it seems the 'backlight controller' has malfunctioned and the entire screen needs replacing (allegedly). Considering a new screen costs almost as much as the V10 itself on ebay these days I'm going to be trying to take mine apart to see if an easier fix is possible, it is more than likely there isn't, but I at least have to try. Let me know if any of you guys have any luck in repairing your phones
Click to expand...
Click to collapse
Update: Having replaced the screen with a new replacement screen, I am still having the same issue, indicating an issue with either the mainboard and/or the chipset. Can't really go much further with this it would seem so unfortunately I don't think the issue has any DIY fix...
Sorry guys... RIP my V10
phelanpw said:
Hi this also just happened to me. Image is working but no brightness in screen except some bright ess in top right corner. Phone overheated a couple kf times and shutdown after this initially happened and consumed 2 full batter chages in minutes. Now the heat and battery problem is gone but screen still dark. Any ideas
Click to expand...
Click to collapse
I have Same problem,, Any solution ? please help me
My LG70 just did this for a few minutes
My LG70 just did this for a few minutes. Scared me to think my phone was dying. Restarted, still the same. While I was googling it, the screen came back on. Hope it stays that way. Really strange to take it out of my pocket and only have the screen lit in the upper right hand corner. I hope this wasn't a preview of things to come. Love this phone and want it to last!

For anyone interested, some info about screen flickering issue.

Seems that a lot of people complain about this bug/glitch. It mostly happens with this device, specific to some carrier like s5 t mobile etc. Mostly what people face is flickering with a green/yellow nuance that covers at least half of the screen, and that happens when you set screen brightness on minimum. Some other ( like me ) also get the flickering while turning the screen on or off. So I started doing some searches over the web, and tried all the 'fixes' possible. Sadly to me nothing worked. Some of these 'fixes' are :
Turning off auto brightness.
Turning off adaptive display.
Turning off screen overlay ( found on developer settings )
Also other strange ones like removing your sd card etc. Few people say that these worked for them, but for me it didn't.
I tried booting on safe mode, and the problem was still there. I also flashed official 5.0 and the same. So the only thing left was to blame the hardware. But I was sceptical about this since the problem is not persistive, sometimes it happens, sometimes not. Sometimes it happens on small scale, sometimes it is worse. Also a lot of people say that their devices were working fine and the problem started after marshmallow update. A certain person on an online forum claims that he/ she spoke with samsung officials and they are aware about this problem and working on an update to fix this. Does this mean it is not physical problem but just a software glitch ? Hard to say, I sent my phone to different local repair shop and they say it is screen physical problem. But maybe they just want to scam me and take money ( new screen costs too much )
After going through all these, I just got the idea to try and flash an older firmware, like kitkat. And to my surprise, on official kitkat rom it still does the problem, but FAR less.
So TLDR if you have this glitch and gave up on all the 'fixes' you found online, try flashing kitkat, it might work for you even if it's not a permanent fix.
I'm sorry to bump this topic being that it seems dead. However after my own research and now my second S5 from T-Mobile. I'm at the same point as you. My research states that it's more of an AMOLED screen issue, which after a factory reset and flash of older ROM and such does make sense. However, at the same time it could be an actual issue with the screen.
It's definitely a hardware issue in my case-cold temperatures exacerbate it ie-I have no flicker issues in the summer, but get flicker issues in the winter if my phone cool's down to the 60s. The flicker goes away if I heat the screen.
It seems the lower the temp, the more wattage (brightness) is required for the display matrix to function; insufficient wattage/heat when the screen is activated, and the matrix collapses. This is why it autobrightness tends causes issues when it provides power below threshold for matrix stability.
Easiest legitimate econimical fix is ordering a replacement screen, if you have reaervations about yiur shop doing it, it's a very easy/cheap/simple process to do yourself and plenty of how to YouTube videos.
okay, I will solve this issue for yall. I have an s5 g900t that had the screen flicker issue and also when temps are cold, the screen would blank out till I warmed the screen. I fixed this issue after a year of having the issue. a temp fix which can damage the device was found by accident when I went to change out a broken rear cam. heating the screen with a heat gun during surgery fixed the issue for a while then the symptoms came back. after much much research and testing, I found the amoled screen was the culprit. I ordered a new screen and replaced it. no more issues. I took the old screen and replaced it to my other s5 which is for testing only and the screen flickered under low light and would not come on when cold. so, if you have a screen that is flickering in low light and/or wont come on during cold, its your screen. replace it and fixed. how long the new screen will last? well 2 years later no problems, yet.
FYI, AMOLED screens are notorious for this issue and the manufacture is well aware.

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