Released on September 19, 2014, this 4.7" screen iPhone is the smaller version of the iPhone 6 Plus. Identifiable by the model numbers A1549, A1586, and A1589.

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No backlight after unlock phone (backlight work during boot)

Hi guys,

recently i repaired iPhone 6 water damaged.

I replaced PMIC, after then phone boot but there are not backlight and touch. I replaced:

- backlight IC

- backlight capacitors

- touch ICs - MESON, CUMULUS


Now after press power button, phone boot with backlight and work normal. When i lock phone, LCD goes off, but when i want unlock phone there are not backlight. Touch and LCD work.

My question is:

Where can be problem? It look, backlight driver do not receive ENABLE signal after booting and do not want work.

Can be here problem with




For what is there this bus?

Sorry for my bad english :)



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2 Answers

Chosen Solution

Those two lines are part of the I2C bus. You will want to check them to insure they are not shorted. I would also look at pin B1 of U1502. That is the Hardware Enable pin. I don't know enough about the internal logic of these IC's to say what could be causing this.

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I fixed so many backlights specially on 6 and 6s. Normally it's filter

But recently I d given iPhone 6s with very low backlight

Checked all caps, filter, diod, coil etc. Everything seemed fine so I changed backlight ic(u2040) no luck

And than I changed main pm ic and problem has gone.

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How do you know that you must replace PMIC? Should i use multimeter?


yes check all the voltage and most importantly recistance of the components.

But you said you have changed it didn't you?

But again your phone is the water damage. Could be anything man.

Have you checked any short?


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