| no Power,
19V stops at first inrush
limiter MOSFET (fg. 1)
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Diagnosis:
- measure Vin at the inrush limiter MOSFETS
- fg. 1: input area
- the first MOSFET is not turned on at the gate
- responsible is this BQ24780s chip
fg.2:VSYS area (https://www.ti.com/lit/ds/symlink/bq24780s.pdf)
- here ACDET should be over 2.6V, but is 1.6V
- so ACOK is not triggered and ACDRV stays 0V
- the shown short reduces the voltage
- through voltage injection i found this:
fg. 3 shorted area
- this cap pulled VSYS down
- we replaced with 1uF/20V (measured at the other 3 caps, which are the same size
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