HP Spectre X360 Charging Problem

[mullspeed]

Hi,

I've previously had the shorted cap and PQ8 problem as described here https://www.badcaps.net/forum/showthread.php?t=82397 and for weeks it's been working fine. Now, after a week without charging and not being powered on (school holiday), the charger isn't detected or working.

The laptop boots ok and there are no shorts that I can determine. 19V comes in, goes to PQ8 but it doesn't get switched on and therefore the source of this FET is at about 3V. The BQ24715 has 18.5V at pin 20 and 2.4V at pin 6 (AC Detect).

I've replaced the BQ24715 twice (in case the donor was also duff) but no difference.

I'm stumped......

[mon2]

Re: HP Spectre X360 Charging Problem

What is the voltage on AD_ID?

Power down and check pq8 for shorts with resistance mode.

[mullspeed]

Re: HP Spectre X360 Charging Problem

AD_ID was 0.47V, so I had a poke around checking some resistances and found that the cap on the 24715LDO pin was shorted to gnd! 12ohms was the measurement. Replaced the cap and the board sprang into life.