lenovo E520 no start main LGG-1 MB10292-2

[poweron]

hello, pressing on button does not light up, on the button there are 2.9v that go to zero by pressing the button, randomly making measurements on Q6001 I realized that by grounding pin 3 RTC_AUX_S5 the pc starts up and works but it does not turns off, the rtc battery is ok, the junctions of Q6001 measure 350ohm, it seems a bit low, what do you think?

thanks

[emestee]

Re: lenovo E520 no start main LGG-1 MB10292-2

Which mode did you use to measure the junctions? Diode testing modes should indicate voltage drops, not ohms. Ohm modes may be too weak to open the junction.

By grounding RTC_AUX_S5 you are grounding the whole 3D3V_AUX_S5 rail, triggering KBC_PWRBTN_EC# and also powering off the RTC section of the hub and a bunch of other things, including the main KBC power itself. This prompts a startup in an inconsistent state. So the weird results you are getting may not be related to the root problem.

Check KBC_PWRBTN_EC# on the EC side when pressing the button.

[poweron]

Re: lenovo E520 no start main LGG-1 MB10292-2

on pin 93 of the KBC I measure 2.9v, and by pressing the power button the voltage goes to zero

[emestee]

Re: lenovo E520 no start main LGG-1 MB10292-2

2.9v is meh. May be ok, may be sign of trouble.

Look at the schematic on sheet 27. The voltage that comes to the resistor divider must be 3.3 (input side of R2704). Check the resistances of all three resistors - are they within the norm? Check the capacitor for a leak. If that's all ok then press the button and see if the KBC is retransmitting the power on signal to the PCH.

[poweron]

Re: lenovo E520 no start main LGG-1 MB10292-2

the resistance values are correct 100k, 10k, 470ohm the C2717 is not installed

[emestee]

Re: lenovo E520 no start main LGG-1 MB10292-2

the resistance values are correct 100k, 10k, 470ohm the C2717 is not installed

Then this appears to be ok. So, if you short the KBC pin to the ground it should start - you're saying it doesn't? But if you short the 3d3v_aux_s5 line it does start?

[poweron]

Re: lenovo E520 no start main LGG-1 MB10292-2

exact

[poweron]

Re: lenovo E520 no start main LGG-1 MB10292-2

exact but it doesn't turn off, neither with button nor shorting 3D3_AUX_S5

[mcplslg123]

Re: lenovo E520 no start main LGG-1 MB10292-2

R2704 and R2774 forms the voltage divider circuit for poweron switch. So you should get approx 3.0V at that point. So getting 2.9V doesnt seems abnormal to me. Did you flashed bios?? I'll strongly suggest to flash bios first before doing anything else.

[emestee]

Re: lenovo E520 no start main LGG-1 MB10292-2

exact but it doesn't turn off, neither with button nor shorting 3D3_AUX_S5

If that is the case then your next step is to see if the EC retransmists the power on signal to the PCH.

[poweron]

Re: lenovo E520 no start main LGG-1 MB10292-2

R2704 and R2774 forms the voltage divider circuit for poweron switch. So you should get approx 3.0V at that point. So getting 2.9V doesnt seems abnormal to me. Did you flashed bios?? I'll strongly suggest to flash bios first before doing anything else.

no, I didn't flash the bios, I'll try to do it

[poweron]

Re: lenovo E520 no start main LGG-1 MB10292-2

If that is the case then your next step is to see if the EC retransmists the power on signal to the PCH.

on which pin of the kbc must be present the signal that goes to the pch? this can also be useful for other cases, it is useful to know

[emestee]

Re: lenovo E520 no start main LGG-1 MB10292-2

on which pin of the kbc must be present the signal that goes to the pch? this can also be useful for other cases, it is useful to know

Pin 117

[mcplslg123]

Re: lenovo E520 no start main LGG-1 MB10292-2

PM_PWRBTN & RSMRST#-both communicate with pch. Infact RSMRST# followed by PM_PWRbtn.

[poweron]

Re: lenovo E520 no start main LGG-1 MB10292-2

I measured PM_PWRBTN #on pin 117 of the kbc , before pressing the button I measure 3,2v and by pressing the button it remains like this, if I put 3D3_AUX_S5 to ground the voltage goes to zero and the pc turns on

[mcplslg123]

Re: lenovo E520 no start main LGG-1 MB10292-2

Pin 73/74/93 are all part of PSL circuit and the problem you are facing is PSL Circuit fault. Probe these 3 pins and you may get the clue.

[poweron]

Re: lenovo E520 no start main LGG-1 MB10292-2

I checked pins 73 and 74 and I measure 3v while on 93 I measure 2.9v, pressing button power pins 73 and 74 remain at 3v while pin 93 as seen previously goes to 0v

[poweron]

Re: lenovo E520 no start main LGG-1 MB10292-2

some advice?

[emestee]

Re: lenovo E520 no start main LGG-1 MB10292-2

Sorry I will have to look at this again later on, at work right now

[poweron]

Re: lenovo E520 no start main LGG-1 MB10292-2

yes yes, when you can