Ipad pro 10.5 2nd gen (A1701) no image or backlight

[john]

So I was working on an ipad (can't talk about the work I was doing since its not allowed here and my little plastic guitar pick I was using as a spacer slipped out of the battery connection part of the board at some point while I was plugging everything back in, including the screen. I realized my mistake when I went to remove it and seen it had slipped out. So I plugged in the four connections to the screen with power on the board ((

So I was expecting at worst a blown filter. The Ipad will not boot now unless the screen is removed. Specifically the bottom right screen plug which I believe to be the display or back light connector. It will boot with no image or back light with this bottom right connector disconnected. I checked what appears to be filters (no leg on ground) and they all have continuity. I did measure a .18 line in diode line which sounds low. My guess is I blew a backlight ic or an image ic which is now shorted with the screen connected. Can't seem to positively identify which ics these are. Sure wish there was a board view or schematics out there for these.

Or maybe I damaged the screen and its shorting out when connected? I sure hope not as they are quite expensive.

Does anyone have any input on what I should be doing here? I'm certain its booting without the screen as I can see it in 3utools and if I use the new 3utool feature where you can see what is on the screen through the computer. When I do this I see the ipad home screen. So it boots just not with that image connector connected

[Jessa_the_Professa]

.18 isn’t necessarily low. This is unfortunately a case where you need to follow rule number one. Look closely at the screen connector (on the screen) to see if it has correctable damage

[john]

Ok thanks. There is quite a bit of circuitry inside this screen under some shields. I suspect something in there is bad. But I’ll have to dremel the shields as the heat to remove will certainly damage the lcd. Another little Apple challenge.

[eDigitCom]

I usually get an tweezers under the corner of the shield and gradual lift the shield off

[eDigitCom]

john I can see it in 3utools and if I use the new 3utool feature where you can see what is on the screen through the computer. When I do this I see the ipad home screen. So it boots just not with that image connector connected

This feature sounds great

So if you connect an iPhone to a computer without the screen attached and run 3utool you can see the display on the PC??

What version of 3utools is this John??

[john]

john I can see it in 3utools and if I use the new 3utool feature where you can see what is on the screen through the computer. When I do this I see the ipad home screen. So it boots just not with that image connector connected

This feature sounds great

So if you connect an iPhone to a computer without the screen attached and run 3utool you can see the display on the PC??

What version of 3utools is this John??

im not sure just use the latest one and click more, and then there is an option for something like “real time screen”
but don’t ever do a restore without the screen on, or you will get impossible to deal with font size. Not sure if there is a fix other than don’t restore with screen on again.

[john]

So I got another ipad, pulled the screen off and same thing, on both of them! So now I have two ipad pro 10.5 that are doing the exact same thing. WTH am I doing? This time I am certain there was no power when I removed the screen as well as put it back on. I don't even remove the connector cover plate until I am sure my small plastic is completely under the battery connector. Also I am certain the screen worked when I removed it as I tested it just before powering down. Now both ipads are doing the same thing, they do quick boot loops if you plug in both of the bottom connectors (there are 4 connectors two by two on this model for the screen)
What is going on ? I need some ideas. I have two ipads here that boot just fine just unless the screen is attached (all four connectors). Am I damaging the screen when I remove it? I have a heating mat at 75C and only use plastic pics. I feel like the screens are coming off as gentle as possible. Has apple set some kind of trip wire here i'm missing?
And yes all filters and diodes measure OK. Though a blown filter or diode probably wouldn't cause a no boot with screen fully attached.

[john]

Got a brand new screen in today and put it on. Still doing the same thing

[Jessa_the_Professa]

so the deal is that you have an iPad Pro that will boot without a screen attached, but will not boot when a screen is attached? Show us a picture of your connector area.

You should be able to figure out just from reading that board where the backlight circuit it, and for iPad Pro the touch circuit is also powered off of vccmain. You can check the it takes a village section of this forum for some helpful posts on iPad Pro backlight/touch issues.

If this was my board, I'd try to isolate the problem. Remove the touch filter--does it boot with screen? How about backlight filter A, then B, etc. What is the behavior of dcps when powering the board with the screen attached, does it act like a vccmain short? What is the vccmain diode mode reading with screen off vs on?

See if you can figure out which line is causing the no boot and then post back and we will go from there.

[john]

Thanks Jess I removed this filter with screen attached and it booted up. Not sure what line it goes to. The power Z bootloop looks just like an iPhone 7 baseband bootloop issue, quick reboots. I really wish someone had a 10.5 they could share diode readings off the lcd connector with me. The resistance on this line looks normal to me at .53 in diode mode.

[Jessa_the_Professa]

That filter looks most similar to the touch filter in the 12 inch iPad Pro. This is probably your touch power and if the device boots with screen attached with that filter missing, it will likely have image and backlight but not touch--is that the case? With the filter off, see if you can figure out why the device will not boot with a screen attached--something about putting a screen there is likely causing a short to ground on main through that filter. If so, then this will likely be a mechanical short that you can see somewhere.

[john]

With that filter removed touch still works (verified by virtual screen in 3u tools, but no backlight or image. I traced that line to what is supposedly a backlight ic according to a google search. I really doubt this is he problem as there is no image either and the diode reading on that line is fine. The only thing I can think of is this is some power supply problem. Some power ic is failing under the load of image and backlight. The only place I have worked on these is around the nand doing reprogramming for reasons I can’t talk about here.

[Jessa_the_Professa]

Since we know that backlight is generated secondary to image, we can guess that your problem is image. And I would agree--the big filter is likely an image power line filter.

You traced back to a mystery ic, and your picture brings to mind a similar ic in the iPad mini retina that I once had to work on after water damage, U1700. From memory, that ic routed vccmain through to become image power and on my data recovery job, that ic was destroyed as were the pads, so I just made a jumper from vccmain to the output and image came back.

We can guess that on this Pro, you either have a vccmain branch at this spot or a 1v8 branch at this spot. MOST LIKELY case, inferring from everything we know about the biology of other iPads, is that the output from the image chip U1700 is short to ground, and that WHEN A SCREEN is in place, that sends data to the CPU which in turn sends an enable to U1700 to activate image power---which is a switch for vccmain into the shorted trace that goes to your filter. When a screen is not present, then the CPU does not enable U1700 and vccmain is not diverted into the shorted line.

How to test.
1.) You should pick up a short on the U1700 side of the missing filter.
2.) Even if not, you could leave the filter off and just hardwire main to the good (connector) side of the missing filter and get image back.

You could also lift up U1700 and swap it with the same one from any iPad mini (I think it is also on the mini original, near the backlight filter)

Let us know what you find.

[john]

OK thanks for that info. I removed the big filter and fed it what I believe to be VCC main (4.2 volts and found all over the board) directly to the connector. Same reboot behavior with screen attached. I don't have any ipad minis right now to steal this from but i did order from aliexpress those "back light ic" that looks just like what i'm dealing with. Will see if that helps any. I really wonder if this is some power managment ic gone bad and just can't handle the load of the screen. There is also no shorts under the U1700 looking ic. Also checking internally with its ground leg, I find no shorts.

[Tech Repair Corner]

john I have an iPad pro 12.9in Gen 2 that is showing the same issues as your iPads. I was wondering if you ever found a solution to the display issue.