hp elitebook 745 G2

[nassih]

hi everyone
i have an HP elitebook 745 G2.the problem is the power button and caps lock is blinking continuously when i put the adapter.
i have replaced a bad mosfet and cleaning little water damage, but still the same problem no short to ground en all the coils .any ideas
ps: all voltages is unstable still sensing except adapter IN rails
best regard!

[emestee]

Re: hp elitebook 745 G2

This is probably a problem with adapter detection. Measure the voltage on the central pin of the adapter.

[nassih]

Re: hp elitebook 745 G2

This is probably a problem with adapter detection. Measure the voltage on the central pin of the adapter.

i have tested with original adapter its working on other hp laptop

[emestee]

Re: hp elitebook 745 G2

i have tested with original adapter its working on other hp laptop

Then start checking the circuit that's responsible for adapter identification.

[nassih]

Re: hp elitebook 745 G2

Then start checking the circuit that's responsible for adapter identification.

yes i have tested and replaced BQ25736, 3vs5 is present.all ALW voltage is present but its sensing not stable.

[emestee]

Re: hp elitebook 745 G2

yes i have tested and replaced BQ25736, 3vs5 is present.all ALW voltage is present but its sensing not stable.

No, adapter identification goes through a separate circuit through an ADC or directly to a KBC input.

What do you mean 'not stable'?

[nassih]

Re: hp elitebook 745 G2

No, adapter identification goes through a separate circuit through an ADC or directly to a KBC input.

What do you mean 'not stable'?

i mean the voltage is random variable (19v~15v).,sorry my English is too bad
ok,i have found a schematic for other hp model, https://www.badcaps.net/forum/showthread.php?t=85724 now when i put jumper between drain and source Q6010 the power button and caps lock is not blinking and the voltage is normal no random voltage but still no start

[emestee]

Re: hp elitebook 745 G2

Ok, first off post the exact board model and revision.

Second, without shorting the input mosfet (note that it's a p-channel), test its control circuit - Q6009, Q6013, ADP_EN. This is to make sure the mosfet is being controlled correctly. If when the main voltage is changing, and the control signal for Q6001 is changing too, you are getting closer to the problem.

Third, do standard measurements on the charger - ACDET, ACPRES, REGN etc.

Which bad mosfet have you replaced?

[nassih]

Re: hp elitebook 745 G2

OK, motherboard model:6050a2644501-MB-A02
Q6010 pin4= 6~15v pin1,2,3= 19.45v pin5,6,7,8=15v~19.45v.
ADP_EN= 1.8v~3.3v
replacd mosfet Q6010.
tanks

Ok, first off post the exact board model and revision.

Second, without shorting the input mosfet (note that it's a p-channel), test its control circuit - Q6009, Q6013, ADP_EN. This is to make sure the mosfet is being controlled correctly. If when the main voltage is changing, and the control signal for Q6001 is changing too, you are getting closer to the problem.

Third, do standard measurements on the charger - ACDET, ACPRES, REGN etc.

Which bad mosfet have you replaced?

[nassih]

Re: hp elitebook 745 G2

ACDET=2.6
ACPRES=3.2~3.3v
REGN =5.8~5.9v
all rest pins of U6000 is not stable except ACDET

[emestee]

Re: hp elitebook 745 G2

ACDET=2.6
ACPRES=3.2~3.3v
REGN =5.8~5.9v
all rest pins of U6000 is not stable except ACDET

Something is oscillating heavily. Do you observe current changes on the PSU?

[nassih]

Re: hp elitebook 745 G2

Something is oscillating heavily. Do you observe current changes on the PSU?

1ma,Imaybe the kb chip no?

[emestee]

Re: hp elitebook 745 G2

1ma,Imaybe the kb chip no?

I've only seen a case like this once and it was the PCH that was pulling voltages up and down, it was visible everywhere, even on BIOS power pins

You need to proceed carefully and write down the measurements. I would start cutting off various parts of the board and see if the problem goes away, beginning with input mosfets.