HP G62 No Power Issue

[harshana]

MotherBoard: DA0AX1MB6H1 REV H

I tested this board with my current knowledge and I found these things.

19v rail ----> OK
3.3v Rail -----> OK
5v Rail --------> OK
1.05v Rail ------> Missing

When I check 1.05v controller (PU8), I noticed that LEN Pin which needs to generate LDO is missing.

According to the schematics LEN pin receive <MAIN_ON> signal from the IO chip.

I guess this signal should present before power switch on. May Be I was wrong because I have very poor knowledge about signals.

However I can see 3v in BIOS chip and also IO chip.

Here I attach the schematics for your reference. Please help guys. Where to go. Im stuck.

[harshana]

Re: HP G62 No Power Issue

According to the schematics LEN pin receive <MAIN_ON> signal from the IO chip.

I guess this signal should present before power switch on. May Be I was wrong because I have very poor knowledge about signals.

I was Wrong. MAINON signal is only present after power on switch. However the thing I noticed now is RSMRST# is missing.

What should I do

[mcplslg123]

Re: HP G62 No Power Issue

check VCC for SIO and AC_IN. Flash bios

[harshana]

Re: HP G62 No Power Issue

check VCC for SIO and AC_IN. Flash bios

VCC and ACIN -----> OK

I see there are 2 winbond Chips.

One chip has 3v on its 8th pin and Other one has no power. Is that normal???

Here I attach the images.

[harshana]

Re: HP G62 No Power Issue

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[mon2]

Re: HP G62 No Power Issue

Is U12 stuffed (soldered) on your PCB ?

[harshana]

Re: HP G62 No Power Issue

Is U12 stuffed (soldered) on your PCB ?

Yes both chips soldered

[harshana]

Re: HP G62 No Power Issue

I see that the U12 is main BIOS which needs to have 3v at pin 8. But the voltage is 0. Is that normal??? No voltage at power switch as well. I see 3v is missing on some places but the thing is 3.3v available on EC bios.

[mon2]

Re: HP G62 No Power Issue

You will have to confirm if the rail is fed from the same source which it appears to be. Have too many other fires in the building to hunt this one down but check the schematic. Perhaps you have a blown trace on the PCB but check for the main regulator that powers this BIOS.

Found it...see attached.

Measure the voltage on mosfet @ PQ20. This section of the circuit needs a review if the +3v is not enabling.

Also - +3v is NOT +3.3v - important to note this in your repair. Separate rails.

[harshana]

Re: HP G62 No Power Issue

You will have to confirm if the rail is fed from the same source which it appears to be. Have too many other fires in the building to hunt this one down but check the schematic. Perhaps you have a blown trace on the PCB but check for the main regulator that powers this BIOS.

Found it...see attached.

Measure the voltage on mosfet @ PQ20. This section of the circuit needs a review if the +3v is not enabling.

Also - +3v is NOT +3.3v - important to note this in your repair. Separate rails.

My bad. I thought 3.3v ok means 3v okay. Just noticed that PQ20 has 0v out. when I check gate 0v at there also.

So I looked PR110 and I see it only has 6.38v which needs to be 10v always pwer.


I should recheck 10v always power line I guess. Am I correct?

[harshana]

Re: HP G62 No Power Issue

Here What I found.

When MAINON signal is low, PQ37 doesn't start to flow. because of that PQ19 & PQ32 gates are high, which connects the power line to the ground.

According to my knowledge, if we need 3v and 5v to be present, then MAINON signal should be high.

I can guess those voltages are only work when the system is at on stage. So Main bios will not power up until IO send MAINON signal.

However 3v which should appear in power switch also missing.

What do you think? May I try to flash EC bios???

I don't have a bios programmer. But I heard that I can use arduino to do that. What should I do.

[harshana]

Re: HP G62 No Power Issue

I did a small research about bios programing using Arduino and the things I noticed is arduino produce 5v which is not suitable for the chip. however, I found that the raspberry has 3.3v. So I will flash using raspberry. Will update the progress soon.

[usyusy]

Re: HP G62 No Power Issue

I see there are 2 winbond Chips.

One chip has 3v on its 8th pin and Other one has no power. Is that normal???

Here I attach the images.

this may be normal, as in some boards, Main Bios has voltage after pressing power-button, as sir mcplslg123 suggested flash clean and tested BIOS for both EC bios and main bios.
for flashing winbond chips, ch341a programmer is ok

[harshana]

Re: HP G62 No Power Issue

this may be normal, as in some boards, Main Bios has voltage after pressing power-button, as sir mcplslg123 suggested flash clean and tested BIOS for both EC bios and main bios.
for flashing winbond chips, ch341a programmer is ok

I ordered Ch341a programmer but It will take around 30-40 days to deliver. So I planed to use raspberry Pi 3 Model B to flash bios. Hope it will work fine. Let's see.

[harshana]

Re: HP G62 No Power Issue

I flashed EC bios still nothing. Even there is no 3v at power button. No RSMRST#

What should I do

[harshana]

Re: HP G62 No Power Issue

In schematics there is a resistor called R74 which connects 3v to power switch. It was missing. I soldered a resistor there and now I see 3v on power button. but still nothing happens

[Sephir0th]

Re: HP G62 No Power Issue

Lid Switch is always something worth to check. Also check for unexpected short at logic signals which should show voltage.

[harshana]

Re: HP G62 No Power Issue

Lid Switch is always something worth to check. Also check for unexpected short at logic signals which should show voltage.

lid switch line has 3v.

What signals should I check mainly?

[Sephir0th]

Re: HP G62 No Power Issue

The power switch line for example and RSMRST# line for example. Also detailed visual inspection of the EC and surrounding area. Who knows what you'll find

[harshana]

Re: HP G62 No Power Issue

The power switch line for example and RSMRST# line for example. Also detailed visual inspection of the EC and surrounding area. Who knows what you'll find

I can't see any short to ground from power switch amd RSMRST#