View source for ZenBook 13 UX334FL Not turning on, 19V stops at the first inrush MOSFET repair

{{Repair Guide
|Device=ZenBook 13 UX334FL
|Affects parts=Motherboard
|Needs equipment=Screwdrivers, multimeter, hot air station, soldering iron
|Type=Soldering
|Difficulty=3. Hard
}}
{{stub}}

==Problem description==
Repairing a ZenBook 13 UX334FL that does not turn on, and does not charge. This specific issue is related to the inrush limiting MOSFETs.
[[File:Input area asus zenbook.png|thumb|Figure 1, input area marked.]]

==Symptoms==

*Not turning on
*Not charging

==Solution==
===Diagnostic Steps===

* Measure Vin at the inrush limiter MOSFETS (Figure 1)
* The first MOSFET is not turned on at the gate
** Responsible is this [https://www.ti.com/lit/ds/symlink/bq24780s.pdf BQ24780s] chip (Figure 2)
** Here ACDET should be over 2.6V, but is 1.6V
** So ACOK is not triggered and ACDRV stays 0V
** The shown short in Figure 3 reduces the voltage[[File:Bq24780s.png|thumb|Figure 2, Bq24780s circuit marked.]]

[[File:Short area asus zenbook 13.png|thumb|Figure 4, shorted component.]]

=== Repair Steps ===
Replace the shorted capacitor. 

* This cap pulled VSYS down
* Replaced with 1uF/20V (measured at the other 3 caps, which are the same size).