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water damage cpu heats up computer doesnt recognise

Hi guys,

I have an iphone 5S in for repair and I can see the red indicators are triggered meaning it has come in contact with water. I have removed the back shield and it looks to be that L19 isnt as shiny as it should be and doesnt respond to ground on the multimeter on eitherside of the coil.

The computer / itunes doesnt recognise the phone however the CPU is heating up so there must be a short somewhere.

Does anybody know what I should try replacing first or the next step to take ?

Thank you

I am an experienced repairer however im just starting out on board level.

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Posted: Dec 22, 2016

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L19 is not connected to ground so you should not expect it to "respond to ground". It is connected between PP_VCC_MAIN and pin B2 of U3. If you want to test it, then measure it's resistance. According to the schematic, it is 200 mOhms, essentially a short from a DC perspective.

So measure both sides of the inductor and see what reading you get.

You won't always find visual cues to what component is bad. Ideally, you want to start measuring your main voltage rails to see if there is anything shorted. Start with PP_BATT_VCC / PP_VCC_MAIN and PP5V0_USB when it is connected to the Lightning port. If those voltages are present or not shorted, then move on to PP3V0_TRISTAR and then PP_CPU/PP_GPU/PP_VAR_SOC and then work your way through all of the rails generated by the PMIC. If you find a missing or shorted rail, then focus on that area.

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iPhone 5s

water damage cpu heats up computer doesnt recognise

Update (12/22/2016)

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