820-02016-A - 5V / 0.02-0.04A / PPBUS_AON jumping from 8 - 12V

[quasimodo]

Hey guys,

title is saying everything. Board is clean. No liquid damage. Looks like new. AON is jumping and cycling from 8 - 11/12V...


Removed F5200 - Pin 1 is 12.3v stable.

Whats can i do?

 

[2informaticos]

What about 3V8_AON and U8100 LDOs?

 

[quasimodo]

3V8_AON: 3.2V unstable

PPVDD_PMU_LDO_PREREG: almost nothing, 0.02-0.08V - Diode Mode Reading: 0.0002 - short?
PP1V5_VLDOINT_MPMU: 1.5V

new U8100?

 

[2informaticos]

Can be faulty U8100, or bad filter cap; there are many capacitors connected.
Remove R8422 and check where the short remains.

 

[quasimodo]

removed R8422 - no short on PPVDD_PMU_LDO_PREREG

now short on: PP1V4_LDO_PREREG

inject voltage?

 

[quasimodo]

C84E5 was the bad guy. board is fixed. thank you.