19v power not passing through

[zhang]

Hi Folks,
Recently I encounter motherboard with board code x451ca rev 2.1
charging ic is bq24725
which comes with 19v power voltage can not pass the both adaptor mosfet ( N channel )
checked for the gate ( should be greater than drain pin ) but it appears to be only 1 volts ( which caused the 19v can not go through and only present 1v on PR8806 )
checked the acdrv pin from ic PU2800 still about 1v
for the ic, vcc present 19v, acok present 2.5 ( which should be normal )
changed few pcs of ic, seems to be the same result

Regards to all

[piernov]

Re: 19v power not passing through

Check if the DC-in MOSFETs are shorted, common issue.

[zhang]

Re: 19v power not passing through

Check if the DC-in MOSFETs are shorted, common issue.

Checked, working normal
replaced with normal working also in vain

[zhang]

Re: 19v power not passing through

Hi Folks,
Recently I encounter motherboard with board code x451ca rev 2.1
charging ic is bq24725
which comes with 19v power voltage can not pass the both adaptor mosfet ( N channel )
checked for the gate ( should be greater than drain pin ) but it appears to be only 1 volts ( which caused the 19v can not go through and only present 1v on PR8806 )
checked the acdrv pin from ic PU2800 still about 1v
for the ic, vcc present 19v, acok present 2.5 ( which should be normal )
changed few pcs of ic, seems to be the same result

Regards to all

seems like I accidentally solved it and yet till now still don't understand what is going on and why it turn on normally
I give 9v power to the adp gate
and it works
just wondering what might be problem

[z3h1r]

Re: 19v power not passing through

There is static electricity. Connect the 19 volt adapter to the device. Short-circuit the device at the DC socket.Asus laptops have such a problem.

[zhang]

Re: 19v power not passing through

There is static electricity. Connect the 19 volt adapter to the device. Short-circuit the device at the DC socket.Asus laptops have such a problem.

if talking about static electricity,
the notebook has been disassembly for about two week with no power ( battery, adaptor, cmos )
that should be quite a long time for non power state

[zhang]

Re: 19v power not passing through

There is static electricity. Connect the 19 volt adapter to the device. Short-circuit the device at the DC socket.Asus laptops have such a problem.

if it is because of static electricity, what should I do next time if I encounter similar ( but not the same ) situation?