Black screen (no backlight?) after LCD replacement.

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iPad mini 4 Wi-Fi

Guides pour la version Wi-Fi de l'iPad Mini 4-modèle A1538. Annoncé le 9 septembre 2015, l'iPad Mini 4 est le successeur de l'iPad Mini 3.

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Ijon Tichy @ijontichy

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Publié: 5 sept. 2018

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Black screen (no backlight?) after LCD replacement.

Hi everybody!

I have replaced LCD in my iPad Mini 4 (A1538). Everything was ok for circa 30 min.

Suddenly, unit made some beepy noise and screen went black.

I was trying few different screens (including original one) but same symptoms: no picture.

iTunes is recognizig it after connecting, so I’m guessing that is backlight related issue (battery was disconnected during replacement).

I have found a lot of information how to fix such malfunction (replacing fuse, filter, making a jumper) but nothing directly related to that model. There is one movie on YouTube: https://www.youtube.com/watch?v=8ElCx1Ep... but mainboard of my unit has no visible damages, nothing is burned and all elements seems intact.

Can somebody guide me what should I do in such case? Post a picture with elements to check/replace?

I wan to buy: https://www.ebay.ie/itm/Ipad-Mini-Backli... as a spare parts.

I’m quite sure that I can do soldering myself, but I can’t find schematics for A1538.

Thank you in advance

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Solution retenue

Minho @refectio

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Publié: 5 sept. 2018

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There is no schematic available for the iPad mini 4. The only way to do board level work on this model is to compare to the other mini’s and the Air’s and infer functionality based on similar design. You’ll need to be patient and jump around from one schematic and board view to another. ZXW at least has the connections mapped out for the mini 4 but no other information.

The linked video shows pretty clearly where the backlight filter is. Probe it and see if it is showing continuity and then probe it in diode mode to see if the circuit is giving a decent reading (~.325). On the LCD connector (smaller one), the Anode pin is the 12th pin from the left on the bottom side of the connector (assuming the short connector is at the top of your field of view and the long one is at the bottom). The three pins to the left and three to the right are the cathode return pins. Start with that and try to determine if there is anything obviously wrong.

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