Released on September 19, 2014, this 4.7" screen iPhone is the smaller version of the iPhone 6 Plus. Identifiable by the model numbers A1549, A1586, and A1589.

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No signal after screen replacement.

Hi guys. I need help with an iPhone 6. Mind you this is not the first iPhone 6 LCD I replaced so I'm not exactly a beginner. I did everything by the book as I replaced the cracked screen and everything seemed okay after reassembly. But after about 30 minutes , an hour tops of testing the signal dropped and I can't seem to be able to get it back. I tried disassembling everything again and looked if everything is in order and seems that everything is properly connected back. The client tried to send it back to warranty without talking to me first and they repair centre said that it MIGHT be that the motherboard got damaged while replacing the LCD but I find it difficult to believe as I have replaced and least other 20 iPhone LCDs in the past without any issue. Now of course I have to take full responsibility and I am evaluating if I should change the whole motherboard or not. If anyone could point me in the right direction and help me avoid doing that I would greatly appreciate it.

UPDATE: No..the person asked if signal problem could be because he changed the screen. As for me...I really don't know...I used plastic tools...quality spare screen. I'm asking my self now if maybe I put the wrong screw but..small update...when I do a factory reset the signal comes back for about 5 minutes in which I'm able to make phone calls after which the signal is lost again. I'm lost...can't figure out what it is. Anyone knows where exactly I'm suppose to look for damage signs? The phone was working prior to the lcd replacement, that, unfortunately I know for a fact.

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I would look for signs of water damage.

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Ok guys so here's where I'm at. Dismantled everything and everything seems fine...no screws were wrongly fitted. So, after further testing I've noticed the following, immediately after boot up signal is working fine, 4G works , full signal. I can call , made a 40 minute phone call and everything was fine, if I continuously call different numbers the phone will work fine with no issues whatsoever but...if I leave it for 20-30 seconds ,basically the time for screen to shut down everything goes south, signal drops, no service displayed and that's it...after 2 hard resets I've got to the point where the signal goes away, no service , than after 20 seconds it comes back full signal bar but I can't make any calls, I get call failed if I try to call anyone, and obviously I can't call the iPhone sim it goes straight to voicemail. I'm running out of ideas, I'm thinking that maybe it's the baseband ic, but how could I have damaged it since it has the metal protection and changing the LCD you don't go anywhere near it?

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4 Answers

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It appears like you have done everything correctly.

Do you have the original cracked screen? I would try to put the old screen back and test it thoroughly. That way you can see if the problem is related to the replacement screen or the logic board.

The other thing I would check is the antenna flex.

iPhone 6 Logic Board Antenna Flex Cable

Take a look at this image and notice it has a small conductive pad.

iPhone 6 Display Assembly Replacement

That is likely meant to ground the selfie camera bracket and, who knows, maybe even act as an antenna. Sometimes, that pad sticks to the bracket more than the flex so it might not have been transferred to the replacement screen. Also, that flex is connected via four connectors underneath the logic board. Maybe one of them came loose.

EDIT 2018/11/18

The iPhone 6 has unfortunately developed a “thing” for GSM/LTE connection/searching issues and over time the repair community has found some classic issues. You can read more about it below but it’s entirely possible that the the issue the OP (Rosu) has was coincidental to the screen repair.

After you have eliminated antennae or network locks as the possible culprit, searching issues on the iPhone 6 are usually related to the baseband IC. The baseband IC is very sensitive, just like the Touch IC's on the 6 Plus; it also suffers from poor quality traces and pads (which could reached the tipping point following a bit of flex during a repair).

 Go to your phone’s dialling keypad and dial *#06#. You should see the IMEI displayed.

 If the IMEI is not displayed, the Baseband IC has to be reballed and two small copper traces (U1/V1) have to be rebuilt and solidified. This is commonly referred to as the “long jumper” solution. You can check out this answer (Service is "Searching" indefinitely) (by @teetopp) as it summarizes the issue really well.

iPhone 6 Logic Board Antenna Flex Cable Image

Product

iPhone 6 Logic Board Antenna Flex Cable

$14.99

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Bravo my friend...I barely touched the cable flex antenna and I've lost signal completely. Seems I've narrowed it down. I'll try to play around with the antenna and see if I can get l it back to life if not replace it. Anyway, I'll keep you updated on how it goes. For now, thanks.

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Forgot to get back to you. You were a life saver. I was in no "no service" zone thinking I had to replace the mobo but replacing the flex antenna did the trick and it only cost me 5 euros to replace it. Seems that is an actual gsm antenna. I cannot thank you enough for pointing me in the right direction after wasting 4 hours googling dousines of sites without so much of a hint. thank you again

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Hi

I have also "no signal" message after dock flex charge change on IPHONE 6.

Wifi is working, GPS also but only the GPRS (calls) doesn't work.

I see you said that after changing the Logic Board Antenna Flex Cable eveything works again but this cable is GPS/WIFI flex , no ??

What is the link between this cable and the GPRS signal ?

Thanks

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Unfortunately changing the gprs antenna was a temporary fix , two days later it was back to the original state. Apparently at the end I managed to damage the motherboard at that's why it wasn't working. I eventually gave up and sold the phone with a huge discount and that was it. Sorry I couldn't be of any more help. You could try the answer the other guys gave me, maybe they will help you

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I would have tested this :

http://www.arete.audio/2016/10/31/iphone...

It's just to test some tape over it and see next time you meet this problem.

Solved it for me before (y)

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Synchronize date and time automatically / connect to Wi-Fi?

Send it back to warranty meant he probably made an appointment with apple and they checked inside the phone.

Well that's bad luck to the customer because now he just permanently voided his warranty when he could've kept the warranty for the next time he really needed to send it back to warranty by having an original screen installed.

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meh....the warranty was voided as soon as he cracked his old screen. Its a 6, so I really don't see how they would have known his screen had been replaced unless the OP did a sloppy repair job.

OP: There is nothing that you could have done to damage the cellular reception if everything went right. I'm assuming you disconnected the battery before removing the old screen, didn't use any metal tools and used only top quality parts. I'm also assuming you didn't do any damage by using the wrong screws. Also assuming that you didn't use unnecessary force when putting it back together.

What is possible is that when the customer dropped his phone, he did damage to the cellular system of his phone. Which again, would have voided his warranty.

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I’m almost sure that signal problems was also before you change the screen it’s just was hard to see it’s because randomly.

That problem very common in ip6 model signal problems the way to check when no signal dial *#06# imei check, if the number didn’t appear the modem have disconnected.

Its can be repair just make sure the technician know what he doing and if he will do it good its will not happen again.

The reason for modem problems is falling and the modem is sensitive sny hit can cause that.

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Rosu Catalin will be eternally grateful.
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