HP LA-D711P no power after not charging

[incorrect]

Hello,

my LA-D711P stop working. found and replaced a failed ceramic at 3VALW.
after that, battery couldn't charge but laptop could turn on.
found that PQ4 was shorted. I replaced the PQ4 but no voltage on gate.

Any idea will be welcome.

Thank you

[mcplslg123]

Re: HP LA-D711P no power after not charging

Which charging IC is in use here?? Measure ACP/ACN/CMSRC/ACDRV/ACDET/REGN pins for voltage.

[incorrect]

Re: HP LA-D711P no power after not charging

Bq25a

acn=0.8v
acp=0.8v
cmsrc=0v
acdrv=0v
acdet=2.64v
regn=5.9v

[DanielDacko]

Re: HP LA-D711P no power after not charging

Maybe this will help.

[mon2]

Re: HP LA-D711P no power after not charging

@DanielDacko - great document !

@incorrect, what is Vcc on this charger BQ IC ?

[incorrect]

Re: HP LA-D711P no power after not charging

I took a look to the bq datasheet yesterday already. I believe that the ic needs replacement, because of the shorted pq4 earlier.i will replace it as soon i receive a new ic and i will keep you up to date.

@mon2 the voltage on vcc seems normal.

[mcplslg123]

Re: HP LA-D711P no power after not charging

What is the resistance on pin5 of 1st dc-in mosfet?? If the resistance is good, then try replacing the charging IC.

[incorrect]

Re: HP LA-D711P no power after not charging

yes it is good 4.3k i think, i checked it yesterday

[incorrect]

Re: HP LA-D711P no power after not charging

Hello again,
i replaced the charging ic but problem persists.

[mon2]

Re: HP LA-D711P no power after not charging

Check the first 2 mosfets mated with the adapter.

After the charging IC replacement, what are the voltages on ACDRV ? CMSRC ?

[incorrect]

Re: HP LA-D711P no power after not charging

Check the first 2 mosfets mated with the adapter.

After the charging IC replacement, what are the voltages on ACDRV ? CMSRC ?

ACDRV and CMSRC still 0V.
I removed the 2nd mosfet and shorted source with drain. ACDRV and CMSRC went to 0.8V.
Also, i found that BATDRV is 1.5V. not sure if it's normal

[incorrect]

Re: HP LA-D711P no power after not charging

update.

while i plug the charger i see a spike of 0.5v on the gate of the first mosfet.
seems like somethings turns the gate off.

[mon2]

Re: HP LA-D711P no power after not charging

From @DanielDacko (see above post), attached are the normal voltages for this charger IC.

Do not remove and bridge mosfets - this can lead to possible further damage.

On the removed mosfet - check the resistance on this part while it is out of circuit:

source to drain resistance ?

source to gate resistance ?

gate to drain resistance ?

With the mosfet on the logic board - do you see the adapter voltage reach the right side of the 2nd mosfet ? What is the voltage ?

[incorrect]

Re: HP LA-D711P no power after not charging

Acn= 0.8v
acp=0.8v
cmsrc= 0v
acdrv= 0v
acok= 0v
acdet=2.6v
iout=0v
sda=0v
scl=0v
ilim=0v
batdrv=1.88v
srn=1v
srp=1v
gnd=0v
lodrv=0v
regn=6v
btst=5.8v
hidrv=1v
phase=1v
vcc=19.5v

Edit: Please note that if i replace the 1st mosfet with the shorted one, the machine works. battery doesn;t charge of course

[mcplslg123]

Re: HP LA-D711P no power after not charging

Refer to LA-A992P schematic page 46 and check PQ102/PD101