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Tablet PC de alto rendimiento de tercera generación lanzada por Apple en octubre de 2018. Modelos A1876, A2014 y A1895.

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IPad not charging enough to turn on

Hey everyone,

Im trying to figure out what is causing this issue. The IPad stucks in a black screen, showing the battery icon (without the power cord) when I press the button to turn it on. This all happened after a screen replacement. I thought it could be the battery connector (which was replaced) causing the IPad to not charge, but it seems to be fine. I checked the resistance between each pin of the connector and the logic board and theyre all below 1 Ohm. So my next step would be checking if the battery is dead or if a part on the logic board is missing. Does anyone have some advices for me? Can anyone tell me if there is something wrong or missing in the pictures below referring to the logic board? That would help a lot.
Thanks in advance.

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Update (18.05.2022)

Some additional pictures from the usb c connector

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Update (05/25/2022)

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Does anyone know if some components are missing here or is this the usual case on these logic boards?

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Solución Elegida

Retrace your steps. If it was was powering up and charging before the screen change , battery connector seems logical, since realistically that would have been something that would need to be manipulated to change the display.

It's possible that was the initial issue. But in replacing the battery connector you then introduced another variable. I would start looking at this area of the board since this nearly all the the lines from the battery connector go through this area. And this is also where the battery gas gauge data would be transmitted. make sure nothing here is bridged, or shorted.

If this information cannot be transmitted to its destination, the iPad may not be aware there is enough power in the battery to power on. Or it may be getting garbled information. I will also note, that there appears to be a missing NTC resistor where I stuck the yellow arrow. (documentation for this model seems to be a bit inconsistent, so cannot say this for sure, but the stuff I have says there should be something there). I'm not sure that this would keep it from powering on, but it might keep it from staying on.

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First of all, thanks a lot for sharing your ideas with me.

The IPad was powering up before the screen replacement. The first battery connector broke by doing so, so I had to change it. As i said before the connection between the new battery connector and the logic board now seems to be fine. The battery connector pins are not shorted or bridged. The screen visualizes that the IPad is charging but there is no progression even if i let it charge for 24 hours.

So i assume that the missing resistor is causing the problem of not powering on (maybe?). Where did you get this information from? Im not able to find anything referring to schematics or parts on the logic board. Do you think its possible to replace this one and how do I get to know which specific resistor is missing here?

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@alex_bdg Sorry for the delay in response, been a bit busy and just now remembered to come back to this. I think it's logical that the NTC resistor being missing is a viable solution for non boot. Based on some data sheets for other charging chips I have seen, an NTC resistor needs to be present for the system to recognize there is a battery connected. And iPads will not boot without a battery.

The schematics and other info I have for this particular model are part of a subscription repair database (akin to ZXW). It's called XinZhiZao. I have noticed it tends to have some information that isn't present in other places for some reason. Even so, there is a bit of critical thinking that needs to be done, as iPads still have less data available and and board views are generally less well or accurately labelled. But, it's better than nothing.

More specifically the schematic I have says it's an NTC thermistor (which is a bit different than a standard resistor) at 10K ohm in a 0201 package.

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@flannelist Thank you for your advise, I truly appreciate your help. Im gonna try to replace the ntc, hoping im not gonna mess it up :'). Gonna tell you if it worked.

Other question: Do your schematics say something about the 4 pads above (highlighted in the pictures I posted)? Is there something missing or is this normal?

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@alex_bdg Looks like those 2 components would be part of a small a debugging circuit for main power. The larger of the 2 components would have been an LED for VCC Main. So it would have been used for testing during the design or manufacture process, but not present on the finalized board.

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@flannelist Sorry for the delayed response but I just wanted to say that your advice considering a missing ntc thermistor was very helpful. I soldered the 10k ohm smd ntc thermistor successfully to the motherboard (a few months ago) but it was quite tricky because of its size :'). I would have never thought that the soldering process would turn out well but my IPad is charging like before. Thanks a lot for helping me figuring out how to fix this issue :D.

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Respuesta Más Útil

soldering on the battery connector looks questionable. has the charge port been checked ?

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Not seperately yet. But if i plug in the power cord the IPad detects it by giving the battery icon on the black screen for about 2 seconds. But it does not charge further than that.

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@alex_bdg check for loose coils

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Seems to be ok. Any other ideas what to check next?

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