Is this saveable? (Backlight driver seriously screwed up)

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iPhone 6

这款4.7英寸iPhone于2014年9月19日发布，是iPhone 6 Plus的缩小版。

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Gigabit87898 @gigabit87898

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发帖于: 2017年2月11日

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Is this saveable? (Backlight driver seriously screwed up)

Hello,

I got a dead iPhone 6 with water damage. It was shorted so I found out the short was at the back light driver. I went to remove it and it fell off the board along with most of the pads. The phone still works and is unlocked but does not have a backlight. I am using it with a flashlight right now and it seems to work fine. Here are pics:

Here's what it looks like now when I tried removing the excess solder, now it does not turn on either.

Another pic after cleaning and polishing

Another pic, this time I know that pcb layer 2 is perfect and layer 1 has about 4/5 traces broken. Might be able to solder it not upside down if I run micro jumpers under it, looks salvageable.

Now I REALLY screwed it up, vccmain is only showing .20 to .40 volts and has no short, it is killing the battery and has no short there either. Tried to remove old copper but that didn't end well.

After cleaning with acetone to make the traces more see able, it looks better when it has alcohol on it but when it dries up you cannot see the traces anymore.

Update:

I had an idea. Since the board is almost unrepairable, I want to try something that almost no one does. Get the baseband, CPU, ram, NAND and the NAND eeprom and transfer then to an iCloud locked board. Touch ID did not work anyway so I can just take it to Apple and they can fix the Touch ID. An iCloud board is $20 and I have nothing to loose, if i do I correctly then I will have working phone minus Touch ID, if it does not go well I do not loose anything but a useless damaged board and a useless iCloud board. Seems easier then running all these wires and jumpers. I will get the board, 0.3mm solder, amtech 559 and new emi shields for it. May not be plausible but it is possible.

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Reece @reecee

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It looks like you have pulled the rest of the pads off for the backlight driver. If it is not turning on, you may have shorted a main voltage line to ground by scraping the pads too much (don't work on phones now, but check input voltage for the IC). There is also a diode missing under the IC now, but I assume this is related to the backlight circuit and not a main voltage line?

Do the above first, if it gets the phone working ultrasonic it to clean any corrosion and flux off the board. Then make a decision whether you want to put more time into this or not.

If you can recover the majority of pads using a solder iron and light scraping, put a new chip on and run wires for the missing pads. If not, you can try securing the new driver upside down on the board, and run wires to the balls under the chip, if you want to have a fun project :)

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I have measured a bunch of voltages, they are al normal and nothing a can find is shorted to ground. When I set my multimeter to diode the voltage drop between vcc_main and ground was 69 and it was still working. That seemed a little low but it was because some capacitors were shorted a little. I cleaned it mode and can see 3 of the pads are still there, but I damaged the board and a few traces. I will post a new picture.

由 Gigabit87898 完成的 2017年2月11日

Do you know what traces were under that and where they go to? Right now I am just solving the no power, the no backlight is another project.

由 Gigabit87898 完成的 2017年2月11日

It is charging the battery, the voltage is going up and all the voltages I have tested are there.

由 Gigabit87898 完成的 2017年2月11日

@gigabit87898 I have no idea, I don't really work on phones anymore, but if it is like a Macbook it will have voltage going to this and a few other things (for example, PP5V_S0 on most Macs power the backlight IC, audio, CPUVR, etc).

The board is in a very bad state, so likely you have grounded the the input voltage rail for this, which may be used for some important components required for it to boot. Grab a schematic and board view to find out what the pads underneath are supposed to go to.

Once you have checked this, you may be able to do a bit of digging to prevent the rail getting shorted, but if you do manage to do this to get it working, you will definitely have to solder the IC on upside down to resolve backlight. It looks like it will be a difficult one to fix, it may not be possible

由 Reece 完成的 2017年2月11日

@reecee i already have schematic and board view, it has vcc_main and pp1v8 and neither is shorted to ground but something else might be. I was only checking voltage rails but it might be something else.

由 Gigabit87898 完成的 2017年2月11日

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I have measured a bunch of voltages, they are al normal and nothing a can find is shorted to ground. When I set my multimeter to diode the voltage drop between vcc_main and ground was 69 and it was still working. That seemed a little low but it was because some capacitors were shorted a little. I cleaned it mode and can see 3 of the pads are still there, but I damaged the board and a few traces. I will post a new picture. — Gigabit87898
Do you know what traces were under that and where they go to? Right now I am just solving the no power, the no backlight is another project. — Gigabit87898
It is charging the battery, the voltage is going up and all the voltages I have tested are there. — Gigabit87898
@gigabit87898 I have no idea, I don't really work on phones anymore, but if it is like a Macbook it will have voltage going to this and a few other things (for example, PP5V_S0 on most Macs power the backlight IC, audio, CPUVR, etc).

The board is in a very bad state, so likely you have grounded the the input voltage rail for this, which may be used for some important components required for it to boot. Grab a schematic and board view to find out what the pads underneath are supposed to go to.

Once you have checked this, you may be able to do a bit of digging to prevent the rail getting shorted, but if you do manage to do this to get it working, you will definitely have to solder the IC on upside down to resolve backlight. It looks like it will be a difficult one to fix, it may not be possible — Reece
@reecee i already have schematic and board view, it has vcc_main and pp1v8 and neither is shorted to ground but something else might be. I was only checking voltage rails but it might be something else. — Gigabit87898

oldturkey03 @oldturkey03 声誉积分: 782.1千 1.1千 893 2.3千 · Answer 1 · 2017-02-11T14:15:55-07:00

oldturkey03 @oldturkey03

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@gigabit87898 if you are really bored and if the excellent answer by @reecee won't work for you, you can always run some jumper wires :-) (Looks like a fun project)

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I have some jumper wire that would be perfect, but what scares me is how would I protect the wires? Would I put epoxy/under fill on then so they don't short anything out or fall out of place?

由 Gigabit87898 完成的 2017年2月11日

Once they are soldered in place you should be good about the movement. I rarely use something called Plasti Dip liquid tape to ensure no short circuit to happen. Of course I use insulated wires to create jumpers.

由 oldturkey03 完成的 2017年2月11日

What about the traces under the IC that are missing? How do I know which one goes where? It does not say in board view or schematic.

由 Gigabit87898 完成的 2017年2月11日

You'll need something like PADS or ZXW to check those traces and where they go to.

由 oldturkey03 完成的 2017年2月11日

I have PADS, but the iPhone 6 one I have is not correct, the Tigris section is completely different and it does not show traces.

由 Gigabit87898 完成的 2017年2月11日

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Rany @rany 声誉积分: 41千 iCenter SARL 15 78 89 · Answer 2 · 2017-02-12T07:02:32-07:00

Rany @rany

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Here's a similar one I did, on a 6S Plus. Just saying that anything can be done if you put your brains and skill to it. It may not be economical, but it is doable.

https://www.facebook.com/microsoldering....

(I hope this is not considered spam, I just have a hard time uploading pictures here because of my snail Internet).

You can even glue the driver in a different location and run jumpers. You'll need to be able at least to solder to a stub of the traces going underneath the CPU. Everything else is otherwise doable if you think out of the box.

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Thanks, I just tried to remove anything that might be causing a short and I think I shorted it more. About to give up, doesn't seem like it's worth it anymore. If I knew what was shorting i would fix it, but there's no short anywhere I could find and still no power.

由 Gigabit87898 完成的 2017年2月12日

Do you think it's even worth it anymore or should I just give up and get a new board?

由 Gigabit87898 完成的 2017年2月12日

I definitely think it is not worth it except for training or "fun."

Otherwise, a liquid damaged board has "osteoporosis" in my opinion. Meaning even if you are able to clean and eliminate all traces of corrosion, the joints have suffered and are prone to failure from drops for example much more than before. Moreover the iPhone 6 is particularly bendy so the risk of flexing to the board is high. Finally, the value of the phone and/or board is not worth the effort economically.

All that being said, I've embarked on a few repairs myself that were not economical either to acquire skill, or to salvage a board that died on my while I was doing a repair, or to impress a potential customer: I do a lot of Be-To-Be board repair and sometimes get boards that have been butchered. I repair them to make a point that we can fix better then others when they give up, and even fix their mistakes if need be.

由 Rany 完成的 2017年2月12日

And yes you did butcher that board. You need to be gentle.

Also the dead board part is the easiest in my opinion. It is pretty straightforward in most cases to determine what might be preventing a board from booting or not displaying, and decide if it is economical to fix. But you need to be systematic in your approach and use the right tools, the most important being your brains.

由 Rany 完成的 2017年2月12日

@rany it kind of look like long screw damage honestly, but do you know what those traces did that I broke? I am just fixing this for fun, I am still learning and wanted to see if I could. I don't care about backlight anymore, I'd be very happy if it even turned on. Do you think I should just give up and wait until I am more skilled or just go for it and see what happens?

由 Gigabit87898 完成的 2017年2月12日

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iPhone 6

Is this saveable? (Backlight driver seriously screwed up)

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