Fourth generation iPhone. Repair is straightforward, but the front glass and LCD must be replaced as a unit. GSM / 8, 16, or 32 GB capacity / Model A1332 / Black and White.

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Why does the backlight flicker after screen repair

I do between 4 and 5 iPhone 4 and 4s screen repairs each week and have been running in to the same issue over and over. Before I do a repair, I test the screen that I am going to use for the repair with a tester cable and old iPhone. The screens appear to be fine when I run the test, but after I install them on the customers' phone sometimes the back light flickers. I try to be very careful with the digitizer and lcd flex cables, and have even started pre-bending them on the dotted lines assuming that I must be damaging them during installation, but they are still flickering. Has anyone else run in to this problem?

Answer this question I have this problem too

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yes i have seen this problem a lot!!!! also test is before install. once its in place its start to flicker.

all you have to do is wait... about 1h-6h and the flickering has gone (in 99% off the cases). don't ask me why...

in my opinion its the low quality of the screen. and yes i buy "original" parts but that just a name. different suppliers give different screens,... the also seem to come in batches. sometimes the whole batch (100-200) screens give flickering, some times none of them...

suppliers keep talking about static electricity, we work esd safe so i thing the quality is the problem

hope someone know's what the real problem is...

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have you fixed it?

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Know this is an old post, but maybe you will answer anyway.. Do you turn the phone off while you wait, or is it okay to have it powered on?

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I think the problem is lousy replica parts, simple as that. I replaced a fine screen (it had broken exterior glass) with an aftermarket display assembly, and it was awfully annoying. I waited more than one month, its flickering pulsating brightness never went away.

Then I replaced display assembly with a pre-used original part, and it works beautifully. I worked very carefully at first replacement, and slightly hurried during second replacement. I doubt it is my fault (installer's fault, improper handling). I think my aftermarket (copy) display was just crappy.

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I am a new tech and am always very careful with the flex cables while installing. I test out the screen before every installation, and then after fully installed, they flicker! I've been getting the same problem, even after we started buying from only our "good" suppliers, with 50% or more of our screens. It has made me very self conscious, thinking I'm damaging them somehow. Glad to know this is likely not the case!

Update

Someone sent me a PM that said you must manually power down the device before unplugging the battery. I have not had any problems with them since! Before, when I would test a new screen, I'd just unplug the battery to complete the installation. Now, I make sure the power flex is plugged into the logic board so I can manually power the screen down before completing the repair. Even our crappy supplier's screens aren't flickering with this method now. Hope this helps!

Update 2

As long as the device is powered down OR you have dimmed/locked/turned off the screen, the backlight issue does not present itself. I have not had a problem with them since I learned this a few months ago.

Even so, the flickering goes away after a bit.

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Hi laserbeanz

What do u mean by manually power down.

That means"before doing any operation to phone we need to power down mobile by using power key and after all installation we need to put battery cable into motherboard?

And then power on phone manually again?

Is it like that?

Please help my screen is flickering at all corners and it happens periodically not regularly.

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I know this thread is kind of old, but I deal directly with a supplier in the states and I've asked him what the problem was with his screens recently. He supplies great screens and I've rarely had any issues, but as of late I get about 50% with the flickering back light. This issue doesnt start until about 20 min after install. He told me the issue was that the glass on top of the digitizer is either too thick or too thin. Its an issue with the manufacturing process. Basically, whether its too thick or too thin causes undue pressure on the back light. Too much glue or thick glass, if that makes sense.

Hope this helps.

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we sell screen, before we send out the screen. we will tested one by one. there is a customer come to our company to test the screen. maybe your screen didn't tested before you get it.

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Brian, if it was too thick or too thin, it should flicker before installing as well since the thickness doesnt change when it's installed, right?

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This is what I was told by the guy who's in the factory. There's no way for me to test this theory. I asked the same question. He says it takes a few minutes for the undue pressure to cause the flicker. It's not instant. I personally think it's faulty ic chips or bad back lights, but I have no way of testing this.

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I have come across this problem several times and I have found the reason why. It usually happens when you disconnect the screen or the battery without shutting the phone down properly.

Once the screen flickers, just turn the brightness down until the flickering stops. After some time passes, slowly increase brightness so that the flickering is not noticeable, after some time you can increase the brightness to full and the screen will be fine.

I tested this out on several screens and it does occur when disconnecting the lcd or battery while powered on.

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hello there.

I agree with iwillfix.

I found that original lcd (the one with the black stripes left and right only have this problem extremely seldom.. but the copy/half original LCD on the cheaper displays have this problem much more often.

a burn-in of about 15 minutes to several hours will fix this problem most of the time.

Since we offer to repair the displays within 30 minutes for our customers.. i tend to buy the original lcd displays... but i tested a new supplier who said it is original but it is not.. ugh... so i have to write a formal paper now to inform my customers about this burn in procedure...

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By ''burn in" Do you mean to leave the screen display on for that amount of time?

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It happened to me after I replaced a screen. I totally agree with iwillfix.

A lot of people say you must turn brightness/auto-bright off/on, wait a little, sing a song, yadda yadda, but if you just wait you're good to go.

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my screen just wont respond to anything i have taken it apart many times and replaced the screen many times and the screen is fine am i messing up the digitizer somehow or. how do you corectly install a screen and digitizer

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This problem occurred for me after I replaced the front facing camera on my 5S on 8/10/2014. The light on the edges of the screen would flicker on the lock screen and when the virtual keyboard was up.

Turning my phone off and leaving it off for a few minutes didn't work.

I went back in and reopened my case and removed the battery connector and reattached it. This seemed to do the trick.

I think it may have something to do with not properly powering down the display if you remove the front portion of your phone (since you yank out the connectors for the face of the phone). I would recommend disconnecting the battery connector before pulling the front face fully off your phone. This is just also good tech advice in general.

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Hei i have the same problem with my new replacement screen, but it start after i restore iPhone with itunes, before that it wors good. Now i seen that if i put on screen totaly black photo, it stops!

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cable is broken. buy another one.

http://www.aliexpress.com/store/1294129

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I just replaced the volume control cable and charging dock as well. Put the phone back together, (twice now, since I went back in to check all the connections,) and the screen flickers at over 30% brightness. Will try to leave the screen lit for 5-6 hours to see if it helps.

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I have been getting this problem with my supply of screens. They used to be great quality, no touch or LCD issues ever. Now every other screens flickers and about half of those customers have to come back after a few days and get a new screen put on. This has been happening with iPhone 5 screens now too. It's a waste of my time and damaging my businesses reputation.

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I replaced my screen today and about an hour of it working properly it started to flicker lightly. I turned it off for about 2 hours and it stopped. later this night it started doing it again so i'm turning it off for the night (6 hours) and ill comment tomorrow if it works.

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I don't think it's necessarily the parts. I just opened my 4s to pop the Sim out because it was stuck so no replacing the screen. Did however took mother board out put it back together and flickers.might have something to do with static?

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I just had this issue of flickering screen tonight. On a normal 30 minutes repair it took me 3 hours, and same problem, flickering. I was turn off device before I start, static protection etc.. Tested 4 screens, some flickers immediately some after a while. This is so frustrating, damaging my reputation and killing my time.

I've looked at all your comments and some I still haven't test yet, bbl with results.

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I have the same issue. I replaced the screen yesterday and opened the iphone 4 again today, because I installed the wrong home button (im new into business...). well, yesterday everything was fine and when I put the phone back together the screen started to flicker. I have one spare screen with a damaged digitizer cable and with this one, there is no flickering. does anyone know why? is my new screen broken?

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Mine was fine when I swapped the screen (iPhone 5s) - I was actually excited as nothing ever seems to go right for me the first time, especially with electronics... of course, 4 hours later it froze again so I did a hard reset. When it came back on, it was flickering pretty bad. I figured I may not have put the connector on properly, but after reading the site I just hard reset again (same result) and then just left it. Eventually the flickering wore off, visibly until it was gone completely.

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have you solved it? my acer liquid z500 have broken touch screen. i removed touch from the front, not opening the phone, display is not broken, but phone dont turn on(not even vibrate) and back led is flickering when charging.

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i too have the same kind of issue.i just fought with the screen replacement guy.Will it work or completely shut down one day? i just want to use it even i flickers,because flickering happens once or twice in a day.

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I have this problem all the time. Its from unplugging the power button before shutting it down.

SOLUTION: Plug the phone in and turn down the backlight as far as possible and let it sit for about an hour

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Hi,replaced iPhone 4s screen and it all works apart from the 4 bottom apps

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I noticed the flickering a while back when I replaced my screen but was able to fix it with the methods above and now it's been 2 weeks and my screen seems to be dim on the right side while the left is normal. I was wondering if this has anything at all to do with the flickering. Please help!

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That actually sounds like it's an issue with the backlight layer on the screen being partially out. Could be that, or could be the backlight coil on the logic board is partially out. If you try another screen and it still looks the same, then it's unfortunately going to be the logic board :(

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