Hp 15 - la-a994p

[amatic]

Can anyone confirm whether I'm doing a good diagnostic. I'm total beginner in these things.

I'm working on the HP 15 board number LA-A9945.

I have only the cable for the power button and the DC jack, RAM and the processor
connected to the board.


On chip U301 RT8243AZQW pins 15-LD03 and 14-LD05. I did not have any voltage.
At 11-VIN pin I had 19V. The rails +3VALWP and +5VALWP were not in short circuit.
I replaced the chip. And on pin 15 I had 1V and at pin 14 5V.
After 20 seconds the chip stopped working.
And now, as soon as I connect my laptop to power, it's U301 is getting very hot.

And I see that +3VALWP is in short circuit, at pin 14 and 15 I have nothing.

+3VALWP is going every were, is there simple way to find short. and what about U301 what I did wrong?

[piernov]

Re: Hp 15 - la-a994p

PU301 should not get hot. If it gets hot, he might be the culprit of your short-circuit so try to unsolder PL302 and check which side is shorted.

[amatic]

Re: Hp 15 - la-a994p

PL302 is on 5V rail. You think on PL303.
I have unsolder PJ302 jumper and short is not on the PU301 side. It is somewere. U18, PU1801... how can I be sure? Is unsoldering components and jumpers only way?
Under microscope everything looks OK.
Is there boardview for this board? I can't find some caps present on schematics.

[subroto]

Re: Hp 15 - la-a994p

Unmount the chip. Then find out short on +3VLDO, if not then unmount the coil OF +3VALW rail. Check the capacitor and also the two MOSFETs before the coil of +3VALW. I hope you'll be able to find the short circuit.

[amatic]

Re: Hp 15 - la-a994p

Short is not on the chip side.

[smali]

Re: Hp 15 - la-a994p

Check u44 (kb9012 )..