HP 8470P not triggering

[usyusy]

Hi,

Hp Elitebook 8470p (6050a2470001-mb-a03) not triggering and give display untill or unless i place -ve probe of multimeter (on 20v dc selection) on the gate of 1st mosfet (page 4, Q6010 P-Channel), any guidance please whats its the science.

Schematic:

https://www.badcaps.net/forum/attach...4&d=1524808562

[mon2]

Re: HP 8470P not triggering

Measure the voltage to ground of ADP_EN.

This is the voltage that must turn on the 2n7002 mosfet to build a voltage divider. Only if the gate voltage is lower, can q6010 enable (P-channel mosfet).

[usyusy]

Re: HP 8470P not triggering

Measure the voltage to ground of ADP_EN.

This is the voltage that must turn on the 2n7002 mosfet to build a voltage divider. Only if the gate voltage is lower, can q6010 enable (P-channel mosfet).

sir no volt there, impedence seems to be ok

[mon2]

Re: HP 8470P not triggering

What is the voltage to ground of P3V3AL ?

You can check at U6100, pin #8.

Also confirm the presence of R317 which is a pull up resistor on the same ADP_EN line.

After the voltage check, remove all power.

Meter in resistance mode (20k or higher or auto).

One meter probe on ADP_EN = gate of the 2N7002 mosfet.

Other meter probe to pin #8 of u6100.

We want to check if the 10K pull-up resistor is present on this gate pin.

What is the resistance?

[usyusy]

Re: HP 8470P not triggering

Sir on pin 8, 3.3v
Could not find r317 as no boardview
Resistance between gate of q6009 and pin 8 is 9.69 k ohm,
For a few number of times it started and gave display automatically

[mon2]

Re: HP 8470P not triggering

Resistance between gate of q6009 and pin 8 is 9.69 k ohm

This test confirms that the pull-up resistor of R317 is present = ~10k ohms.

So now it seems that ADP_EN is not being driven.

Connect a piece of wire to ground and other side to DRAIN pin #3 of Q6009.

This will force the voltage divider to enable with R6015 (pin # 2) going to ground.

Does this turn on the laptop ?

[usyusy]

Re: HP 8470P not triggering

Yes sir doing this turn on the laptop but if i connect ground before inserting power plug
2ndly ldo voltages 3v & 5v generared, but not the 3v/5v coil voltages, is it normal in this laptop

[usyusy]

Re: HP 8470P not triggering

any clue

[mon2]

Re: HP 8470P not triggering

Monitor ACOK when the logic board does not trigger.

Is this a logic low? The 2n7002 should trigger when ACDET and also ACOK are within the voltage range that confirms the adapter is present and suitable.

[usyusy]

Re: HP 8470P not triggering

Monitor ACOK when the logic board does not trigger.

Is this a logic low? The 2n7002 should trigger when ACDET and also ACOK are within the voltage range that confirms the adapter is present and suitable.

Sir Both ACDET and ACOK remains stable

ACDET is at 2.62V

ADP_DET (ACPRES) is stable on 3.3 and also reaching at SIO.

[mon2]

Re: HP 8470P not triggering

Check the voltage of ADP_EN at pin #63 on KBC @ U300.

Check the voltage after button press for power ON.

Is there a flash device @ U365 on your board?

The contents of the firmware may be corrupted. Suggest to reflash it. Suspecting that you could download the latest firmware from the website.

Then force the logic board to turn on using the resistor turn on trick by pulling gate voltage low using a jumper. Then reflash the logic board using their normal bios upgrade method. The same process should update and fix the firmware inside this KBC local flash.

Then remove the bypass wire and test like normal.

Does ADP_EN work properly after a fresh flashing?