Lenovo 500-15isk LA-C851P without CPU voltage

[kokono]

Lenovo 500-15isk
LA-C851P

i measured all voltage, only cpu dont work
there is NCP81208 chip for three rail voltage :
VCC_core VCC_GT and VCC_sa
only one of three voltage working .ist 1volt
two voltage ist null . i replaced 81208 chip ,but dont change. also i chnaged two NCP81253 together, one have voltage another ist null. also dont change
So i think 81208 and 81253 not defect and problem ist another place.
i can see three pin Communication (SOC_SVID_CLK ,SOC_SVID_DAT,SOC_SVID_ALERT) that connected direct to cpu .
any person have idea for my problem ?
How one of three voltage rail working , because all enable pin ist same but with seperate PWM ?

i dont found datasheet for 81208 but i thinks ist similar NCP81243

[fauzanmint]

Re: Lenovo without CPU voltage

Chek all your pgood pins

[kokono]

Re: Lenovo without CPU voltage

i checked
i am sure that +VCC_SA(one of three Rail voltage for NCP81208) ist ok ,plus VR_PWRGD
Also i think +VCCIO is good.
Have an idea?
i reprogram Bios with this file.maybe my problem ist Bios ???
please check my bios

[kokono]

Re: Lenovo without CPU voltage

No one can help?

[SMDFlea]

Re: Lenovo without CPU voltage

I got your PM. Try this bios.If it doesn`t work keep testing .

[RJARRRPCGP]

Re: Lenovo without CPU voltage

Looks a lot like 2015! So an absurdly short life before a failure!

[kokono]

Re: Lenovo without CPU voltage

I got your PM. Try this bios.If it doesn`t work keep testing .

thx for reply
i reprogram, now i have VCC_core(1 Volt clear) without VCC_GT.
i think my problem ist Bios
in addition, my Bios chip isn't 25Q64 . ist 25Q064A13. maybe ist important

[kokono]

Re: Lenovo without CPU voltage

I got your PM. Try this bios.If it doesn`t work keep testing .

Do you can modifying my bios program ?
with your Bios ,VCC_Core working only VCC_GT dont worked
i am sure that dont have hardware problem

[mcplslg123]

Re: Lenovo without CPU voltage

VCC_GT here refers to GFX Core ?? If so , it can be missing coz of many reasons like Bad bios, Bad ram stick or slot, PCH, Vcore ic(i rule it out as you have already replaced it) and missing DRAMRST# signal.

I'll suggest to check DRAMRST# signal on pin30 of Ram Slot. It should be 1.3V approx.

[kokono]

Re: Lenovo without CPU voltage

VCC_GT here refers to GFX Core ??.

i thinks No, because i have GFX voltage

[mcplslg123]

Re: Lenovo without CPU voltage

i thinks No, because i have GFX voltage

ok. I didnt looked at the diagram. Just thought of it. Thanks for correcting.

[kokono]

Re: Lenovo without CPU voltage

Update :
today i checked again, i can see when press start button,The LCD turns on and gets darker but without backlight
can i connect "VCC_Core" Enable pin to "VCC_GT" Enable ?

[Pferd5]

Re: Lenovo without CPU voltage

did you solve the issue?

[kokono]

Re: Lenovo without CPU voltage

Yes,After reprogram Bios,and without VCC_GT, i changed a lcd cable and working

[RotVik]

Re: Lenovo without CPU voltage

Yes,After reprogram Bios,and without VCC_GT, i changed a lcd cable and working

If I am getting it correctly a bad LVDS cable was causing VCCGT to be missing?

[piernov]

Re: Lenovo without CPU voltage

https://logi.wiki/index.php/User:Pie..._I_solve_it.3F