Released September 25, 2015. Model A1688/A1633. Repair of this device is similar to previous generations, requiring screwdrivers and prying tools. Available as GSM or CDMA / 16, 64, or 128 GB / Silver, Gold, Space Gray, or Rose Gold options.

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iPhone 6s motherboard short after replace u2 ic

Sorry for my bad English

iphone 6s motherboard short after replace u2 ic. Then i remove u2 ic but still short is there, anyone can help me

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It would help if you told us which voltage rail is shorted.

What led you to believe that U2/Tristar was the problem?

When dealing with a “dead” phone, you have to start at the beginning and check PP_BATT_VCC, PP_VCC_MAIN and PP5V0_USB. I would start by checking to see if those rails are shorted to ground. If one of these rails is shorted to ground, then you will need to identify what is causing the short. It could be a bad decoupling capacitor, conductive debris or defective IC that is directly supplied by those rails.

Then you move onto the PMIC and check the voltage rails it generates:

  • The PMIC generates ~15 voltage rails. They are all important (for obvious reasons) but the ones to check first are as follows: PP_CPU, PP_GPU, PP1V8_SDRAM, PP1V2_SDRAM, PP_VAR_SOC, PP0V95_FIXED_SOC, PP3V0_Tristar, PP3V0_NAND, PP1V8_ALWAYS and PP1V0.
  • The PMIC also generates, what I would consider secondary, yet still important voltage rails for the following sub-systems: PP3V0_MESA, PP1V8_VA_L19_L67, PP3V0_PROX_ALS, PP3V0_PROX_IRLED, PP3V0_IMU, PP3V3_USB and PP3V3_ACC

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Quality info right here, Thanks for this


I have a question about the voltage rails- are they always present, even when the device is turned off?


@morticool Most of them are present all the time (once the phone is powered up) but a few are only present when needed, such as PP_GPU, the LCM rails etc.


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What makes you say "motherboard short"? Do you actually have a short to ground on a power line? If so--which one?

Or are you using the term "motherboard short" to mean "phone won't turn on". In this case you have an equal chance of the opposite problem--an open line or bad chip. Since Tristar is required for the phone to boot, and is the last thing you touched--I'd start there.

Differentiate between a short and an open data line with D.C. Power supply

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