HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

[loopster]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

Yeah, you are right, of course, Sephir0th. It measures fine out of circuit.
(I am loosely following your vids on YT btw. Good stuff, keep up the great content).
I'm just starting out with this, and was dubious myself.

The charger is indeed not original, but it has the center sense pin with 19.3 volts on it, and puts out 19.8.
I have to wait for a suitable adapter for this size of barrel connector to hook up
an original HP adpter to the board. Altough, I don't think the charger is causing any issues here.

[Sephir0th]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

Try with a known good charger of correct wattage and the magic might happen. Otherwise we'll see us here again.

[reformatt]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

HP's are very fussy with chargers. Sometimes my bench supply doesn't work, but a proper one does. You get 3 blinks usually on the charger light if it doesn't like the charger. I always use an OEM charger as a sanity check for any laptop.

[gs84]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

You got the same laptop? Would it be safe to connect the adapter and measure the voltage with the QM3002M mosfet off the board? It's not turning on anyway?

no it's just the picture of your MB from Internet. Remove this resistor and measure voltage again

[loopster]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

Are you referring to this thread to check whether the EC is pulling the voltage down
to 1V on the 2.2Ohm resistor? Should be 3V or 3.3, right?
https://www.badcaps.net/forum/showthread.php?t=77778

[gs84]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

If you using wrong power adaptor, then all these attempts at repair are in vain. Really difficult to help in this case

[loopster]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

Since, as we have already established, I don't have the original power adapter, so far I've checked with a 90W universal (blue tip connector) +
with 230W, 120W and 65W original HP chargers (from Elitebooks and Probook) via a 7.4mm to 4.5mm blue tip adapter.
The ADP_SIGNAL voltage is ranging from 19.4 to 18.9V with these, and according to piernov, at a minimum the 230W or 120W adapter should be sufficient
https://www.badcaps.net/forum/showthread.php?t=95945

HP use a resistor between 19V and center pin, completely different from Dell and not compatible. Any HP power brick with correct tip and same or higher power rating than what the board requires will work.
With lower power rating the machine won't turn on if battery is missing/dead/discharged.

So I don't believe that not using the original charger is the issue here,
and if necessary, I could try with a 150W and a 200W as well ;-)

I'd be surprised if this Pavilion is expecting something totally different.
Anyway, if there's someone around who knows what the original charger puts out on the ADP_SIGNAL pin, I am eager to learn :-)

[loopster]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

I also borrowed a linear power supply from work, and now injected 1V with limited current on the 2.2Ohms resistor. Current draw is 0.35A, which is quite (in fact very) high I think. Since there is supposed to be 3.3 there, is there any objection to injecting 3.3V with say 1A (or more, as the case may be) to see whats causing the current, i.e. gets warm/hot?

[Sephir0th]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

Well, i have to admit that i was likely wrong before.

Please check resistance to GND at the same point. We probably have a (partial) shorted VREG3 (+3VPCU). So yeah, in this case the EC does not work properly. It is just a bit confusing, that +3VALW and +5VALW are up anyway. It seems they're enabled from somewhere else.

However, if it turns out to be the truth, you are 99% "just" dealing with a dead Embedded Controller. check on which side of the resistor you have the lowest resistance then.

[loopster]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

Thanks for your reply. Resistance is around 960 Ohm on both sides of the resistor.
There is no discernable difference.
Edit: on further measurements, it's a teeny bit higher on the left side, maybe around 2 to 3 Ohms.

[Sephir0th]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

This would fit to my actual assumption, although 960 Ohms would be the highest partial short, I've ever seen so far.

So, lift the 2.2Ohms resistor from at least one pad and try to not lose it. Now plug the charger and see whether you get stable 3.3V on the left side.

If so, inject into the right side again and check whether the EC is noticeable getting warm.

[loopster]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

I removed the 2.2Ohms resistor, and the voltage now measures 0.86V on the left pad
and 1.03V on the right. Weird, nothing I can wrap my head around :-)

[Sephir0th]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

This did not went like expected, again.

If you still have the bench PSU available, inject into both sides, like before and share how much the rail takes on each side. When you're done, you can solder the resistor back in place.

[loopster]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

Zilch on the left pad, 0.36A on the right. Resistance to ground on the left in the Megohms,
on the right I get nonsensical readings depending on the measurement range I choose. Took two different multimeters. From 60Ohms up to 5k? I am currently recharging the batteries for both to see whether they read bullshit due to low charge...

[Sephir0th]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

Regarding the schematics of a similar device, at the right of the 2.2Ohms resistor is +3VPCU_KBC while on the left is +3VPCU, so maybe we're dealing with multiple faults here but from my understanding at least the EC has a serious issue and should be replaced.

I have no clue why +3VPCU still doesn't reach its proper voltage when the EC is disconnected from this rail, though. Imho your best bet is to replace the EC first and see what happens. Inject into the resistor again as soon as you have removed the EC, to confirm the partial short is gone.

[loopster]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

I just can't believe it. I injected some more, this time 2V at 0.4A current draw and the short cleared itself
You literally could see it fizzle out on the bench power supply, slowly going down.
I now have the white light on the charging port
Weird case. Will reassemble the thing tomorrow and give an update.
Edit: battery is also charging. Hopefully no further damage

[loopster]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

Quite a coincidence, the whole thing went remarkably like this one here:
https://youtu.be/6lGRpNXuK3I?t=1918

[loopster]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

I've reassembled the laptop, but it won't POST. It's looping every five seconds or so,
no reaction to capslock. I see 1.09V coming up on one CPU phase, but no voltage on the Ram. Nothing getting warm, just looping.

[Sephir0th]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

Altough it is is pretty weird what recently happened, it might be some progress. So, if your obervation is correct and the RAM supply is the ONLY supply without voltage, then we might have a start point. Otherwise please clarify what's present and what is not in this "loop state".

[loopster]

Re: HP Pavilion 15-cs1042ng - unknown 3.3/5.0V LDO

Tbh, there's not much else coming up aside from this one CPU phase. All other coils
around the GPU, the CPU and the RAM are without any voltage.
The last thing I could feasibly try now is probably reflash the Bios with a version found in this forum.