Touch is not working. Missing a voltage?

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iPhone xr

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Joseph Hughes @joesipaq

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Postado: 28 de abr de 2018

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Touch is not working. Missing a voltage?

Hello all,

More of a technical question... I have an iPhone 6 with no touch. Before lifting cumulus I was poking around for voltages and am missing PP5V1_GRAPE_VDDH. There is no short to ground on that line.

I pulled U1501 and replaced it with one I had on a doaner board that might have been bad. I lost all image on the screen but had backlight after that.

Retracing my steps, I reballed the original U1501 an stuck it back on and the phone is back to how it was.

Should I order and install a new U1501 or is there something else you would advise me to check first?

Thanks all and happy repairing!

Joseph

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daniel @tech_ni

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Postado: 28 de abr de 2018

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did you try meson to see if it could be an issue

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Honestly no I have not. Before pulling it off I thought I would check voltages going to the two.

If it were an ip6+ they for sure first thing would be an M1 jumper. But in this case, no stress on the board seems to make any difference in it working, so I was leaning away from classic touch diseases (also being a 6 not a 6 plus) are there some inputs I should test out for menson? Or what would you recommend I do to it?

28 de abr de 2018 por Joseph Hughes

cumulus and meson have connected lines like CUMULUS_TO_MESON_VSTM_OUT_N, CUMULUS_TO_MESON_VSTM_OUT_P, CUMULUS_TO_SAGE_BOOST_CLK_EN, TOUCH_I2C_SCL, TOUCH_I2C_SDA

28 de abr de 2018 por daniel

also did you check resistance on j2401

28 de abr de 2018 por daniel

I didn't check resistances on j2401, somehow that passed my mind .... Surprised. That could easily tell me what it might be.

Is it normal for U1501 to have 2 of the 3 power outputs OK and the third dead? That's my primary thought on this one at the moment. I don't have the schematics here with me at home, butbinkimda thought that they would all be present, or none.

28 de abr de 2018 por Joseph Hughes

I will definitely check those lines though on Monday

28 de abr de 2018 por Joseph Hughes

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Honestly no I have not. Before pulling it off I thought I would check voltages going to the two.

If it were an ip6+ they for sure first thing would be an M1 jumper. But in this case, no stress on the board seems to make any difference in it working, so I was leaning away from classic touch diseases (also being a 6 not a 6 plus) are there some inputs I should test out for menson? Or what would you recommend I do to it? — Joseph Hughes
cumulus and meson have connected lines like CUMULUS_TO_MESON_VSTM_OUT_N, CUMULUS_TO_MESON_VSTM_OUT_P, CUMULUS_TO_SAGE_BOOST_CLK_EN, TOUCH_I2C_SCL, TOUCH_I2C_SDA — daniel
I didn't check resistances on j2401, somehow that passed my mind .... Surprised. That could easily tell me what it might be.

Is it normal for U1501 to have 2 of the 3 power outputs OK and the third dead? That's my primary thought on this one at the moment. I don't have the schematics here with me at home, butbinkimda thought that they would all be present, or none. — Joseph Hughes

iPhone xr

Touch is not working. Missing a voltage?

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