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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Water damaged iPhone with no visual damage or corrosion

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When i was taking off the shields i floated this chip and i lost it, can someone tell me the type of the chip, so i can get a new one.

I tested the screen and it works, all the connectors on the board are looking good, no corrosion or oxidation, i cleaned the board with alcohol , removed all the shields and visually inspected it, but still it does’t turn on. At the moment i do not have ultrasonic cleaner.

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3 Answers

Chosen Solution

The missing IC is U_LB_SW and it is part of the Low Band circuitry. IMHO, this is not a required IC and should not impede the phone from booting. If you want to replace it, you can either scavenge it from a donor board or order one on Aliexpress.

Daniel makes a good suggestion and if that isn’t the issue, the you need to start probing the circuitry to see if there any shorts. Start with VCC_MAIN, BATT_VCC and then move onto the PMIC outputs.

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So in theory this missing IC wont't interrupt the work of the phone?

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And yes i don't see any damage from water around the capacitor, but it should be somewhere on the edges because the water probably soaked from there.

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I've never tried a board with that IC removed so I can't say for certain. However, it doesn't look (according to the schematic) like it would be critical. Worse case, replace it first and then troubleshoot.

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Maybe the alcohol cleaning took effect but not on the same day, because today the phone booted up without a problem, so you were right about that ic.

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did you check the capacitor beside the wifi chip before removing the shields as its the most common issue

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No i didn't probe the capacitor before removing all the shields, i did now, and it looks fine, i tested around with continuity mode and it's not shorted nor any visual damage from water. Like Minho said now i will test VCC and then continue probing other lines to spot the shorted i guess.

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that cap is vcc_main so it would have told you if vcc_main was shorted before removing the shields. check the battery connector to check for a vbat short

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I was getting to think that it was a vbat short because there was no power, but then the screen turned on with some stripes on it.. So then i realize that the connector was little bended and loose. Тhe cleaning took effect!

And is it normal the CPU to get very hot when booting?

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The home button’s flex cable caused the problem, because i tried connecting only the LCD and it works fine, but when i connect the home button to the board, the phone immediately goes off, or when i connect the cable while the phone is off it doesn’t turn on. Now i saw oxidation where the home button connects to the flex cable on the back side of the screen.

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its possible i have had phones with bad home buttons before that caused the phone not to boot. as for the cpu getting hot it could be anything

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Yup it's the home button!

But for the cpu, it gets hot only when booting, after that it's absolutely fine.

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