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Old 03-01-2021, 05:39 PM   #1
mferna14
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Default Hp ZBook 15 G2 turns on when adapter connected

Hi all, I am working on a Hp ZBook 15 G2... Very wierd kind of problem it has. The status right now is, I have removed the battery. As soon as I plug in the AC power adapter, NB turns on by itself & works 100% fine. Then in windows I shut down & it goes off... & after off, the Fan runs in high speed & No display at all & no power LEDs are lit. With this status said, Again when I press the power button & it does turn on & the fan speed becomes normal. I have updated the BIOS & checked the CMOS battery, no spillage at all on the motherboard, very clean inside., So in short when the notebook has power of any kind battery or the Power adapter, without the power button press the fans spins fast till the power switch is pressed again. Any tips will be greatly appreciated. Thanks
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Old 03-01-2021, 10:51 PM   #2
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

Not only fan is spinning but if you check your 3/5V standby is also working. Problem is in VS line. It is getting transferred without pressing powerbutton. You need to find out the circuit responsible for switching of 3/5VALW to 3/5 VS. If you have schematic, post it or atleast mention mb part number.
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Old 03-02-2021, 05:53 PM   #3
mferna14
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

Thanks mcplslg123 for your reply. This HP ZBOOK15 G2 use Motherboard LA-B381P.. Hope this is good enough for you to at least give me a tip, from where to start trouble shooting?
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Old 03-02-2021, 11:02 PM   #4
mcplslg123
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

You can refer to LA-9241P schematic as reference. Check page 34 of this schematic. You need to probe your DC to TC conversion. Most likely EN( sometomes labelled as ON) is not removed after shutdown and that's why your VS voltage is transferred. May be some other reason but this aspect is worth probing. The IC may be TPS2296X/G5016 or something similar.
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Old 03-03-2021, 03:59 AM   #5
Pfudaniel
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

got the exact same problem on a asus gl703gs! il keep a eye on this thread!
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Old 03-03-2021, 02:03 PM   #6
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

i was solved this problem last week by replace u45 it was shorted
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Old 03-03-2021, 10:53 PM   #7
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

Quote:
Originally Posted by menshawy View Post
i was solved this problem last week by replace u45 it was shorted
Glad to know that. Since schematic is not attached, can you mention U45 was which component??
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Old 03-04-2021, 01:20 AM   #8
Pfudaniel
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

wud love to know wich component this was aswell!
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Old 03-04-2021, 05:54 AM   #9
menshawy
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

it was shorted between pins1,2 and 7,8
u45.jpg
u45-1.jpg
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Old 03-04-2021, 11:08 AM   #10
mferna14
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

Thank "menshawy" for the tip, will try to repair, I just left it aside.
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Old 03-05-2021, 03:15 PM   #11
mferna14
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

Hi "menshawy" you are genius.. I have no idea how you traced this U45 component to be defective, but that was right on target & spot on. This exact component was defective too on my motherboard. Replaced it from a donor board., all works fine. Thank you very much, really appreciate yours & all involved in this thread to resolve the problem.
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Old 03-06-2021, 06:32 AM   #12
menshawy
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

thanks friend
but This is not from me, but it is a success from Allah.
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Old 04-15-2022, 11:38 AM   #13
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

Guess I have a similar issue, Zbook 17 G2 LA-B391P.

With battery only notebook works good, also restarts etc are possible.

With AC connected (with or without battery) laptop doesn’t post when powering on, only 5 blinks.
When restarting in windows with AC the same, 5 blinks.

Without battery laptop starts automatically, no Post. CMOS is at 3,09 V.

Bios was flashed and EEPROM (16 MByte) was swapped, no change.

Guess here is also a similar Problem?
Schematic available?
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Old 04-15-2022, 04:29 PM   #14
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

@Conste - can you link the schematic of the LA-B391P if on this forum ? Or post it if you have it.

Otherwise, review the DCIN connector and check the voltage from the adapter.

Then confirm how far this voltage is able to travel onto the logic board.

Measure the voltages on each of the first 2 mosfets (source; gate; drain).

Which charger IC is onboard this logic board ?
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Old 04-16-2022, 03:28 AM   #15
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

Good morning and thanks for the reply.

I do not have the schematic.

It is getting more strange. When I power up or plug in AC or battery laptop starts by itself always (with or w/o CMOS bat.).
I get no screen, just 5 blinks and fan at full speed.

When I power it down then without CMOS battery and any battery or power and start again it posts (maybe then some voltage is discharged?!).

First mosfets are good, PQ101 + 107 (4423) are in parallel, source 19,5 volts, gate around 6 v, and drain 19,50 v.
Then comes a single one, other type (MDU1512). Source here 19,5 volts, gate around 25 and drain 19,5 v. After that comes the shunt resistor for current sensing.

Charger chip is BQ736

I use this schematic:

https://drive.google.com/file/d/1D5P...lnphXTgcW/view

When I desolder U24 +5VALW -> +5VS it also starts when I put power to it

Last edited by Conste; 04-16-2022 at 04:50 AM..
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Old 04-16-2022, 11:22 AM   #16
mferna14
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

Here you go... hope this helps you...
Attached Files
File Type: pdf Hp ZBook 15 G2.pdf (3.51 MB, 21 views)
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Old 04-16-2022, 11:50 AM   #17
Conste
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Default Re: Hp ZBook 15 G2 turns on when adapter connected

I think this schematic isn't the fitting one. U45 and U46 have 8 pins in your schematic, but in my case U45 has 6 and U 46 has 5 pins.
The one I linked from ZBook 17 G1 (LA-9371P) seems to be closer to my board LA-B391P. Unfortunatley I cannot find the exact schematic.

But thanks for your help !! :-)

When I power off the board (PWR_BTN to ground for 3 sec) the board shuts down and also all voltages (3VS, 5VS, 1.05VS and +3VALW). +3VALW and +5VALW are still there but not passing the MOSFETs, which switches when powering on.
So I guess all is good in this case.

But what does make the unit start from itself when I plug the charger or battery to it?

When charger is plugged in and board is manually powered, and I then plug in battery, it also starts from itself.
When I power it off then manually it charges the battery as normal.

Last edited by Conste; 04-16-2022 at 12:49 PM..
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