HP EliteBook 840 G5 charging issue

[bembeno]

this laptop was not poweron when i check i found no volt on the gate of the mosfet after the charger port i use a diod to move the 19 v from drain to the source of the mosfet and it power on and work good but no battarey charging and i found only 3.3 volt on batt socket so i replaced the charging ic with the same and putba mosfet after the charger port insteadof the diod when i checked i found about 11 v on the gate of the mosfet and the laptop work good i checked the batt socket and found 13v -3.3 -3.3
and the batt charged to 1% and not Increase i want to know can if abattaery issue or charging circuite

[mon2]

Re: HP EliteBook 840 G5 charging issue

Are these modifications the same as the factory design?

If not, do not use other bypass tricks.

Remain to use only what is onboard.

The charger IC will measure the current draw on each power rail and will throttle the current / voltage based on the feedback circuits. This is based on the original factory design and components expected to be onboard

Can you link or post the schematic of this unit?

If not available, which charger IC is onboard?

Which mosfets are present for the 2*DCin? Battery mosfet? High side / low side mosfet?

Often the battery not charging is due to a leaky mosfet.

[bembeno]

Re: HP EliteBook 840 G5 charging issue

no schematics avaliable charger ic no isl 9538

[doc_aj30]

Re: HP EliteBook 840 G5 charging issue

Again my hp elitebook 840 g4 charging problem bring up your name
I can not appreciate enough all the help you’ve given on these subjects
Now I think it’s my time to plead with you for your guidance

I have similar issues as to many
Presently I have swapped to a new battery and am still getting an orange charge light
Absolutely nothing on screen,keyboard,fans or diagnostic leds
Checked original charger to find 19.5V on the inner ring and the centre pin
At the doc in transient voltage suppressor I get pin 1=2v approx and pin 2=19.4V and pin 3 is =0V

No components show obvious stresses

Being an electrical design engineer I posses fair rework skills and measuring equipment

Problem….no schematics! No real laptop experience. This is making debugging far more difficult

First question….do those suppressor checks seem right?

Second question….if they are fine where can I locate the mosfets you often recommend to check next?
As always thanks in advance for all you are able to offer

[doc_aj30]

Re: HP EliteBook 840 G5 charging issue

Thanks mon2

[mon2]

Re: HP EliteBook 840 G5 charging issue

Locate the silkscreen markings and post the details or picture here. There may be a schematic in the schematics forum.

Otherwise, what is the charger IC onboard?

Trace the dcin connector and there will usually be 2*dcin mosfets (usually N-channel) and the charger IC is often the TI BQ series.

Start with reviewing the voltage to ground of the charger IC.

We need to know the topside markings of this component.

Then, voltage of:

VCC
REGN
ACDRV
ACOK
ACDET

For now, remove the battery.

Post your measurements and list of pin numbers.

[doc_aj30]

Re: HP EliteBook 840 G5 charging issue

Wow…..really need the schematic

Find only DC marking…….looks to be dcin near voltage suppressor
No markings for
VCC
REGN
ACDRV
ACOK
ACDET

Posted board pics from charger connectors to battery connector

Checking as per your advice the schematic depository

[doc_aj30]

Re: HP EliteBook 840 G5 charging issue

https://www.badcaps.net/forum/attach...2&d=1671790996

Think this is it…..or close

Sheet 29 starts the dcin jack circuit

[doc_aj30]

Re: HP EliteBook 840 G5 charging issue

Something’s changed
Charger measures 19.5V
Inserted charger does not
Looking to remove components for isolation testing

[doc_aj30]

Re: HP EliteBook 840 G5 charging issue

Got board layout and schematic

https://www.badcaps.net/forum/attach...2&d=1671790996
https://www.badcaps.net/forum/attach...3&d=1671790996

Using viewer
http://boardviewer.net/

See page 29
Removed d6035 still no voltage at jack 6000 pin 1 or 3
Charger tests 19.5V 19.5V on inner ring and centre pin when removed(so good I think)

SIGNAL pin shows as an input….can this feed back to charger to shutdown voltage when inserted?

Looking to remove L6035 and L6036 for isolation then maybe C6035 for short

Suspect SIGNAL is shutting down something

[mon2]

Re: HP EliteBook 840 G5 charging issue

Measure the voltage to ground of:

PVADP_DC
PVADP

If you do not have a voltage at both of these locations then there is a connector or shorting component fault.

Remove all power -> meter in resistance mode.

Measure the resistance to ground at both of the above locations.

Measure without the adapter and then insert the adapter connector but do not plug in the 120VAC into the wall socket. Just checking if the mechanical mating of the DC connector is solid or not.

[doc_aj30]

Re: HP EliteBook 840 G5 charging issue

No power anywhere
All resistances are high…..no direct shorts
Mechanical mating checks out

Replugged adapter….plugged in…..feel test indicates Q68100 getting hot
See page 8 of schematic

[doc_aj30]

Re: HP EliteBook 840 G5 charging issue

And Q60010!

[doc_aj30]

Re: HP EliteBook 840 G5 charging issue

Q60010 is on page 7

[mon2]

Re: HP EliteBook 840 G5 charging issue

Remove all power -> meter in resistance mode.

Measure the resistance across the mosfet pins:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement of these 2 mosfets.

[doc_aj30]

Re: HP EliteBook 840 G5 charging issue

Will do
Did remove r6000(page 7)….now I get a PVSYS = 19.8V
Does that now point downstream? Like Q6000 and Q6001. Or Q6005 and Q6006

[mon2]

Re: HP EliteBook 840 G5 charging issue

Yes, seems so.

Measure the resistance to ground of the drain pins (5-6-7-8) on Q60005.

[doc_aj30]

Re: HP EliteBook 840 G5 charging issue

Q6005 is green on schematic…..all green components not installed i believe

Q6000 shows drain to ground of 2 ohms!. Shorted. BUT gate and source test HI??

So C60010,C60011,C60014 and Q6000 are the issue

Could Q6000 drain short to ground with source and gate not shorted? That should be unlikely

Cap shorts are rare. Will check

[mon2]

Re: HP EliteBook 840 G5 charging issue

Flux and remove Q6000. Then measure the resistance to ground again but on the PCB pads only.

Do you still have a short condition? If not, measure the resistance across the removed mosfet pins while it is on your work table.

Likely the fault is a shorted cap in this region. The mosfet removal is only to isolate the sections of the power path.

[doc_aj30]

Re: HP EliteBook 840 G5 charging issue

Will do this a bit later…….thanks for your help. Hope cap is the answer