Screen won't turn on at all after swaping mainboard - Any advice? - Galaxy S6 Q&A, Help & Troubleshooting

Hi all,
I had broken my phone's back cover and bent the middle frame too. So I bought a live demo version of S6 to use it as a donor. I swapped the mainboards over and only can here the noise it turns on and buttons light up, notification light come up but the screen stays black. So I swapped the mainboards back and with the demo mainboard the screen comes on as it should. Even I tried a third mainboard from a working phone the screen remains blank with that too.
Not even the charging logo would come on with different mainboard!
So I don't know what I could do with it!!!!
Any advice?
Thank you!

Related

Screen is blank but touch screen works ***HELP***

I recently got a touch pro of a friend with a damaged screen that didn't turn on but the touch screen was responsive. Apparently he sat on it and the screen broke.
I then acquired it and replaced the LCD screen and i turned it on but all it shows is a blank black screen with the backlight on. I was tapping while it booted up and it was making that beep noise so i know the touch screen works. What do i do now.
dazz245 said:
I recently got a touch pro of a friend with a damaged screen that didn't turn on but the touch screen was responsive. Apparently he sat on it and the screen broke.
I then acquired it and replaced the screen (with digitalizer) and i turned it on but all it shows is a blank black screen. I was tapping while it booted up and it was making that beep noise so i know the touch screen works. What do i do now.
Click to expand...
Click to collapse
if the lcd is damaged and you only replaced the digitizer then that wont solve the problem, the digitizer just sits ontop of the lcd and recognizes your touches, hence why it mite know that your touching the screen but the screen is still blank
mancsoulja said:
if the lcd is damaged and you only replaced the digitizer then that wont solve the problem, the digitizer just sits ontop of the lcd and recognizes your touches, hence why it mite know that your touching the screen but the screen is still blank
Click to expand...
Click to collapse
I replaced the LCD along with the digitalizer. Tats what i meant.
Sounds like either the new screen is inop on fit (fraid you need another to test, then send the first back as faulty), or the fault is not the LCD itself.
Possibily its the wrong screen, or its not installed correctly, or you damaged either the screen or the controller when installing.
I'm afraid you dont have many options - take it apart & rebuild to ensure correct parts & fitment, spend £££ on alternative parts to see whats broken (or serious £££ on test equipment!), send it off for repair or give up!
I'd go for option 1 first
If your friend sat on it hard enough to break the screen, i'd be looking for any damage / cracking to the boards / ribon cable mounts and be looking very carefully at the mountings of any IC chips. Incedently, when (s)he sat on it, did the screen work at all? and was it 100% working before they did?
Okay thanks for the replies. I just bought a flex cable where the slider thing is because the old one looked a bit old and flexed out and on inspection of the old screen i found a tiny rip on the screen's flex cable too. I wait for my cable and see if it works and if it doesn't then i'll sent the screen back as faulty and get a new one and if that doesn't work then I'll give up and sell it again
hi
sorry to wake up an old thread.
so what's your solution/conclusion?
is it the flex, or the LCD that broke?
i have the same problem right now.
thanks
was mainboard

Problem with the backlight

Hi! Two days ago, my phone dropped in water , i put them immediately in rice until today. When start it with the power button, i felt the vibration and i hear the open sound. But the screen remains black... but i discover that it was just the backlight because when i watch the screen under a lamp i can see the interface and slide between pages... but its very dark. Is it possible to change this backlight? or just wait few other days to allow time to dry fully. I welcome your suggestions! thanks
samnup said:
Hi! Two days ago, my phone dropped in water , i put them immediately in rice until today. When start it with the power button, i felt the vibration and i hear the open sound. But the screen remains black... but i discover that it was just the backlight because when i watch the screen under a lamp i can see the interface and slide between pages... but its very dark. Is it possible to change this backlight? or just wait few other days to allow time to dry fully. I welcome your suggestions! thanks
Click to expand...
Click to collapse
When there's water involved, IT's hard to know exactly what damaged. Could be just stain on the ribbon connectors, a burned fuse/diode/resistor (all of them micro sized) etc.. or just the LCD's backlight damaged entirely.
Keep it on rice for more time. I would make the battery to discharge to 0%, But it's also more recommended to keep the phone OFF. Only my friend LUCK knows.
To change the backlight, the whole screen needs to be changed.
Backlight died on me. Possible moisture.
First, it was on boot loop (on stock rom)
i went to restart it (holding power button and volume down)
then the screen turned bright white, restarted it and then the backlight died, dismantled the phone, now still in rice, also happened on 2nd April.
Any help is greatly appreciated.
Sherman Han.
Problem Solved.
coly37 said:
First, it was on boot loop (on stock rom)
i went to restart it (holding power button and volume down)
then the screen turned bright white, restarted it and then the backlight died, dismantled the phone, now still in rice, also happened on 2nd April.
Any help is greatly appreciated.
Sherman Han.
Click to expand...
Click to collapse
Took it apart down to the Screen (not the screen layers), left it in rice, works like a brand new now. Cheers.
I just replace all the frame and lcd for a new on my nexus 5, but the problem was still there... no backlight, i can see a little bit the screen, but it's very dark... do you have any idea for try to repair this, because now i don't think that it's the screen but more a motherboard or power problem for the backlight :S
exactly same problem here
nexus 5 phone dropped in water.
Backlight went out permanently - rice didn´t help.
Can see the display working using a flashlight - so rest of the phone seems to be working ok.
Just pruchased a new screen, put it all in and still the same problem: display works, touch works, backlight is off.
So it seems the backlight part of the display receives no power - anybody has an idea how to fix that?
thanks
I have answer to this!
I have had this problem like 3 months now and i finally fixed it.
Basically what i did was that i bought a broken nexus 5 (only the screen glass was broken) and tried to swap every part one by one. The one that was not working was the main dock!
It is a cheap fix, like 10£ on Ebay.
I am writing this post because anyone else haven't.
I hope that someone sees this.
I now copy this message to all other threads so people can fix their nexus 5's
PS:as you can probably tell English isn't my first language.
Hello! I am having the same problem. The cell phone fell to the floor and the next day the problem began. The display is not broken.
What are you taking about when you say "main dock"? Motherboard aka mainboard?
Thanks!

Problem with Display-exchange

Hello,
First of all i dont know if this is the right forum for my question. If not so please notice me.
After my Z5 dropped on the floor i got an broken Display. I bought a new Display and changed it, but i think i broke the LCD-Flexcable after i pulled carefully on it to get it inside the case. The effect is after phone turn on i get only the backlight but the screen remains black. So for a test i switched my old broken display in it but the effect is the same, only backlight and black screen. After a few seconds the phone led blinks 3 times red and the phone restarts. What the heck is now? Anybody get the same case? I handled the mainboard with care, dont remember to damaged the connector in anyway. Does the Flexcable needs to be protected with a tape so it couldnt be grounded on someway?
Sorry for my bad english. Thanks for any help!
After a second and a third display swap the error is still the same. It seems somehow i damaged the motherboard. I swapped the phone against a new one.
Please help, same problem ...

Nexus 5 - trying to repair it. Screen? Other issue?

Hi
I am trying to fix my Nexus 5. Couple months ago I dropped a mug on the phone. The result: cracked screen. I ordered a new screen with the whole front housing so only thing I had to do was remove cracked screen with frame and replace it with new one. When I did it I turn on the phone but I saw only a short blink of the screen. After lots of attempts of I came to conclusion that I probably damaged the new screen or it was already damaged. So the screen is black. When I plug the phone to PC everything works perfectly. I can browse the memory etc.
I would like to ask you whether my conclusion is correct and the only issue is the screen which has been damaged by me or the seller.
One more thing is that when I charge the phone or it is attached to the PC beside the black screen I can not also see any light from notification led.
Best
micro
If the old screen can still display an image, move the parts back to the old screen to check for issues.
HI. Thx for reply. I don't remember whether cracked screen was functional in terms of displaying image. I will try to attache the old screen and will let you know.
Best

Nexus 5 Display not working. Don't know what to replace.

So, I was trying to replace my Nexus 5s camera and I disassembled the main motherboard. Replaced my camera and everything but after I reassembled the phone, I found out that there's no display. The LEDs work fine, because I see them light up and I see that the screen is black but it's a bright black and the screen is on. So after tampering with it, I found that the little USB charger port wire board wire thst connects just above the battery (idk how to describe it, its the orange strip that locks the battery in place) had a direct correlation with the display. If I unplugged it, the screen would go dark and off. If I replugged it, it would be on again. After doing this a few times, I actually got my phone's display to show for a little while before it went away to black again. So will buying a new orange strip part work or would I have to go to the bottom where the little screen digitizer is? I'm sorry if the problem is unclear because I really don't know how to say it or explain any better. Please help.
Replacing that strip is actually not easy.
With the device open, try to apply a little bit of force on the plug of the orange strip, there are mentions of the contacts stop working after upluging/pluging back.
You probably could buy a front frame (glass, touch, lcd and chassis) from ali cheap.

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