iPhone 6 Logic board not booting. DCPS shows 200 mA draw

Question

iPhone 6

Das iPhone 6 mit dem 4,7 Zoll Display ist die kleinere Version des iPhone 6 Plus und kam am 19. September 2014 auf dem Markt. Es hat die Modelnnummern A1549, A1586 und A1589.

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Hama @hamard

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Veröffentlicht: 29. Jan 2019

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iPhone 6 Logic board not booting. DCPS shows 200 mA draw

Slightly water damaged iphone 6 totally dead.

removed the logic board, all the shields, & cleaned in ultrasonic solution branson EC, …

Found no shorts anywhere( vcc main, pp_cpu, pp_gpu, var, sdram, …). Also all the rails’ voltages seem to be in range.

Connected the Logic board only to DCPS. It does not even boot but draws 200 mA.

PMIC gets warm but not hot.

help would be appreciated!

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Gewählte Lösung

Minho @refectio

Rep: 221,4 Tsd.

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Veröffentlicht: 30. Jan 2019

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Did you check ALL of the PMIC outputs or just the main ones? A faulty subsystem can pull the whole system down as well and it is often overlooked. If they all check out, then check the main subsystems that aren’t powered by the PMIc, such as MESA,CHESTNUT, BACKLIGHT. Then check the I2C lines to insure they are balanced and within range and take a look at the PMIC Reset lines (those that can be probed) to see if the problem is there.

Finally, check the BBPMU outputs as well as a damaged BB system will impede the phone from booting.

Also, what areas of the board were more corroded, that could give you some clues about where the damage actually is.

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Update:

PP 1V8 SDRAM rail reads 0.52 V

???

1. Feb 2019 von Hama

Check that power rail with the phone unpowered in diode mode to see what reading you get. There may be a partial short that you will need to elucidate.

1. Feb 2019 von Minho

Found the shorts:

Backlight driver —> 0.18 A

U5302_RF —> 0.02 A

Both are removed.

No booting ( from zero goes to 0.12 A & repeat itself)

DFU recovery on iTune recognizes the board but haven’t gone farther. (Did not recover). Trying not to loose data.

?

6. Feb 2019 von Hama

PP 1V8 SDRAM. Ow reads correctly 1.8

6. Feb 2019 von Hama

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Check that power rail with the phone unpowered in diode mode to see what reading you get. There may be a partial short that you will need to elucidate. — Minho
Found the shorts:

Backlight driver —> 0.18 A

U5302_RF —> 0.02 A

Both are removed.

No booting ( from zero goes to 0.12 A & repeat itself)

DFU recovery on iTune recognizes the board but haven’t gone farther. (Did not recover). Trying not to loose data.

? — Hama