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ZenBook 13 UX334FL Not turning on, 19V stops at the first inrush MOSFET repair | |
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Device | ZenBook 13 UX334FL |
Affects part(s) | Motherboard |
Needs equipment | Screwdrivers, multimeter, hot air station, soldering iron |
Difficulty | ◉◉◉◌ Hard |
Type | Soldering |
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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.
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 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
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).