820-02020 - Reboots when under load - Corrosion around PMIC

it-solve

Member
Got this with spatters of water all over the place, but the main corrosion is around PMIC. Cleaned and reflowed, but suspecting bad contacts underneath. Before I lift it up (haven't done it on such big chips) and reball it. Any recommendations or suggestions?
Done this method on CD3215 and is a breeze -

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Also noticed these little dots on supposed to be 0ohm backlight VDD resistors. But they measure 100Ohm (without lifting them up). That should be OK, right?
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2informaticos

Administrator
Staff member
UP800 can't be powered up through 100 ohm resistors; so these resistors are bad.
Be sure no short to ground at UP800 pins.

PMIC area looks really ugly.
Do you get any voltage there?
 

it-solve

Member
The whole system runs fine until I start a video on 4k. It plays for a second and freezes with colourful patches and reboots.
PMIC voltages on surrounding coils vary from 0.6 - 0.8V. Three big coils on the opposite are all on 3.3V

No short on any components surrounding UP800
 

it-solve

Member
The only severe liquid impact is on the PMIC. Is there anything else I can check? The system diagnostic says all is good.
I was thinking perhaps a corroded pad on PMIC is losing contact when more power is drawn. Now it does it even when casually browsing the web.
 
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