iPhone 6s Display Replacement: How to Diagnose and Repair Damaged Backlight Issue

Question

Hello, when replacing the display on the iPhone 6s I damaged the backlight. On the phone you can see the image only under the flashlight and it's only when I look closely. I would like to diagnose what might have been damaged, but I don't even know where to start. I upload pictures of...

Anonymous · Accepted Answer

forehead,
I see that nobody wants to help him ... so can I?
for starters - take pictures in high resolution, nothing visible on these. I omit the fact that the protection (foam) covers everything that may be important. I'll write you where to take it off - but more on that later.

in iP6s we have 7 systems working for the screen. Several overlap with the touch service (due to the beginning in the same connector), these will skip:
- screen power supply,
- backlight - start from here
- e2prom i2c
- display signal control
- touch interfaces, combined with approaching the ear and response to lifting (such an additional function - the phone turns on if you pick it up) I skip,
- J4200 connector
It's all called the "Kepler system"

there are also systems (electronic components of many elements, cooperating and shared with other sub-systems) Mesa and Mamba, I / O data exchange systems, display PMU / power management unit /, Mojave and "led backlight driver" - that is what for now you will be interested.

start with this:
FL4211, FL 4212, FL 4213 filters for 240 ohms, discover and check for short circuits,
to this are connected the capacitors respectively: C4211, C4212 and C4213 all on 100PF, 25v, NPO-COG in housing 010005 also discover and check for a short circuit.
so much for now, I have to go. I'll write later,

Added after 2 [minutes]:

PS, I attach a photo

just in case. Write if you can read it and then understand it.

Anonymous · Accepted Answer

Rafal-PMU Display is on the other side of the board, at a depth of about the end of the processor. How would he damage it without removing the disc or flooding?
It seems to me that even a mechanical short circuit should blow components closer to the connector. The lines are secured, especially ICs.
(well, I assumed that the CD was not removed ...)

However, I do not understand what "anode / cathode line" means? Do you use a mental shortcut ...
You don't mean "PP_LCM_BL_ANODE_CONN" and "PP_LCM_BL_CAT1_CONN" and "PP_LCM_BL_CAT2_CONN" but you can check it on the testpoint, TP20, 21 and 22, respectively. Am I thinking right?

best regards for now.

raptowny13 · Answer

Why do you find that you damaged the connectors on the disc? In my opinion, you damaged the backlight ribbon coming out of the display. Look at her.

onlynojoke · Answer

I suspect that somewhere there could be a short circuit .. I have changed screens several times and I would rather exclude the display, at least at first glance nothing can be seen

raptowny13 · Answer

Unless you bought a replacement.

onlynojoke · Answer

I will add that after switching on the phone for the first time, it worked normally for about 30 seconds before it went off ... several times

Added after 30 [minutes]:

It seems that the upper filter is damaged .. FL4211 2400HM-350MA 0201, can anyone tell where I can buy it?

gsmowiec · Answer

Draw from a donor either in China (aliexpress)

onlynojoke · Answer

Do you know if I will find this part on the iPhone 4s? As I wrote in Google, on ebay I got the same parameters (240 OHM 350 MA) in some part for 4s but without a photo so I can't identify it

RafalB · Answer

In 6s in the event of content on the screen, and the lack of backlight very often the LCD converter (PMU Display) is to blame Of course, if there was no mechanical damage to the chokes in the anode / cathode lines

krisczrn · Answer

Isn't it better to start by making sure that the LCD is functional?

Anonymous · Answer

krisczrn - read posts understood

RafalB · Answer

I don't know how and why it's raining but he dies and I mentioned it more than once I think that licking the LCD panel can do a lot with it. As for my anode / cathode you are right, I meant it.

onlynojoke · Answer

Hello, yesterday I had the impression that I eliminated the problem, but it did not finish. A friend with whom he works read that it is possible to solder the path there (we used a copper wire from headphones). And it actually worked. After returning the phone, a few hours later a customer calls me that the screen is blinking, described it as a light bulb that is gaining power, not visible at first glance but tedious. On the same day I ordered backlight filters from abroad and they will not come until next week, I hope that after their replacement the problem will disappear permanently.

Gentlemen, I have two other problems - one of them is the crackling speaker in the iPhone 6s (speaker replacement did not give anything), and the other the bar at the bottom of the screen (iPhone 6, about 0.5cm long) which maps what should be in the bottom part in the upper part. I do not know whether to set up separate topics or maybe you could comment on how to possibly diagnose it. greetings

gsmowiec · Answer

No comment... Do you use pliers or a crowbar to open the phone?

onlynojoke · Answer

Please, do not comment in my direction, because I did not deal with it, neither was this path my proposal and I have full confidence in the competence of my colleague.
The idea was not the best, but it served as a good diagnosis. Now we are just waiting for parts.

iPhone 6s Display Replacement: How to Diagnose and Repair Damaged Backlight Issue

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