Lenovo ideapad 710s-13isk no power

[koby058]

Hi

Lenovo ideapad 710s-13isk i can see 5vALW but cannot see 3.3VALW

i can see that EN1 present but EN2 is not

Can you please help find fault ?

attached schematics abd photo of board en2 area

[Sephir0th]

Re: Lenovo ideapad 710s-13isk no power

Please onfirm whether 5V_EN is indeed present or not

[koby058]

Re: Lenovo ideapad 710s-13isk no power

Please onfirm whether 5V_EN is indeed present or not

Yes, I have 20v on EN1 and 3.3v on EN2

[Sephir0th]

Re: Lenovo ideapad 710s-13isk no power

But at PU4501 Pin11 (3V_EN) is missing? Weird, but can't be hard to solve since it comes the missing enable comes from 5V_EN via PR4515. So find PR4515 and check voltage at both sides.

Do you have a short to GND at 3V_EN by any chance?

[koby058]

Re: Lenovo ideapad 710s-13isk no power

I think i made mistake in the problem description

Please let me try again

on PU4501 pin11 (EN2) is present 20v
on pin12 (EN1) not present 0V

I think I found PR4515 it has 3.3v on on side, its resistance is 0.33M ohm

attached photo

[Sephir0th]

Re: Lenovo ideapad 710s-13isk no power

I think I did a mistake too. So it seems like PR4515 is missing by factory and 3V_EN will be pulled up from S5_ENABLE, so probably only AFTER power button press and for this reason no issue at this point.
Check whether S5_ENABLE is indeed not present, whether you have 3.3V at the power button and whether the power button itself works as supposed to be.

[koby058]

Re: Lenovo ideapad 710s-13isk no power

the computer turns on for a few seconds then turns off (fan spinning)

Also, can you please explain how did you understand from schematics that 3.3 will be available only after power on ?

[Sephir0th]

Re: Lenovo ideapad 710s-13isk no power

Was just a shot into the blue, but since the board does power an with even the fan spinning, it seems like it is exactly like this.

However, you have very likely a completely different issue then which has probably nothing to do with 3.3V.

you should check the voltages which come up, while the board is on so we can look where it is stuck in the sequence. Also resistance to GND measurements of each power rail (at least of the coils) would be helpful at this point.

[koby058]

Re: Lenovo ideapad 710s-13isk no power

OK, this machine is tricky, I will share

today i played with it and when i removed the nvme ssd it turned on and post.
then when i re assembled it. again, it is powering on but no post.
some time it is post and most of the time it does not.

i can see that cpu is getting very hot and i saw now that when it powers on i see multiple color dots on the screen randomly flickering

Video

I will be glad to here any opinion

[Sephir0th]

Re: Lenovo ideapad 710s-13isk no power

So it turns out to being a weird one, hm? we can forget the 3V_EN now I guess...

So we have either a display or a graphics issue. I guess we should able to exclude the display by checking whether the behaviour is the same with external screen. Try and report pls

Unfortunately my bets are on graphics issue

[mcplslg123]

Re: Lenovo ideapad 710s-13isk no power

EDP cable and screen checked??

[koby058]

Re: Lenovo ideapad 710s-13isk no power

The laptop work fine on external monitor also run furmark on it and it works, I will try another screen.