Lenovo Ideapad 3 15IML05 MB : GS452/GS552/GS752 NM-C781 not trigger

[kamel]

Hi Ideapad when Plugged in 3.3vALW and 5vALW are on, but 1.05vALW and 1.8vALW absent. Power led lights and remains always on and laptop not trigger..
Found a burned spot on LV5075B IC, replaced with a new imported IC, but 1.05vALW and 1.8vALW still failing. .
EC IT8586E working voltages and signals are all ok except PBTN_OUT# 2.44V not changing when power button is pushed and EC_RSMRST# always 0.1V ??
Reflashed EC IT8586E and Main bios with newly download dump from Lenovo site to no avail.
Should I fix again a new L5075B and replace IT8586E to solve the issues.
Thanks for any suggestion.

[kamel]

Still waiting for your suggestion to help fix the issues. Thanks.

[mon2]

I see an EC bios dump in my database. Have you reflashed the EC bios? Always backup the original (twice & verify the filesize against the density of the device) before erasing and reflashing with another.

https://www.badcaps.net/forum/troubl...-lcfc_nm-c781p

[mcplslg123]

What is the point of circling some points on the pdf file without specifying what voltage is present or absent there?

Its wiser to mention all the enables/inputs along with outputs of this IC. this IC is a combination of multiple ic-so the info should be very detailed.

If anything is missing, its standard practice to check resistance to GND on that rail.

Overall, not much info to help you out.

[kamel]

[QUOTE=mon2;n3620072]I see an EC bios dump in my database. Have you reflashed the EC bios? Always backup the original (twice & verify the filesize against the density of the device) before erasing and reflashing with another.

https://www.badcaps.net/forum/troubl...-lcfc_nm-c781p[/QUOTErevert

Thanks for your reply.
Yes as mentioned above, I did reflash Ec and Main Bios with a dump from Lenovo support to no avail. Will try the bin you posted and revert.

[kamel]

What is the point of circling some points on the pdf file without specifying what voltage is present or absent there?

Its wiser to mention all the enables/inputs along with outputs of this IC. this IC is a combination of multiple ic-so the info should be very detailed..

The check points I circled are necessary for issuing 1.05vALW and 1.8vALW which should be present when adapter is plugged in (S4-S5 state). As the issue is "not triggering", the other voltages are not concerned at this stage. I attach new photo of LV5075B with voltages and signals measured before powering laptop.

If anything is missing, its standard practice to check resistance to GND on that rail.

Of course I did check resistance to gnd of failing outputs, no issue found.

+3VALW,+5VALW and 3VALW_PCH are present and my concern is why 1.8VALW and 1.05VALW are not outputted though all the conditions for their issue are present and LV5075B was replaced with a new imported one ? Should I suspect the new IC to be manufacturing defected ?

Any new suggestion is welcome.

[mcplslg123]

Both +1.8V and +1.05V rails are enabled by PCH_PWR_EN which in turn is issued by SIO. It should be 3.3V and not 2.4-2.5V

Measure PCH_PWR_En on SIO pin-is it 2.4V there? If yes, remove PR506/507 one by one to see if it rises to 3.3V.

[kamel]

[QUOTE=kamel;n3620806]

I see an EC bios dump in my database. Have you reflashed the EC bios? Always backup the original (twice & verify the filesize against the density of the device) before erasing and reflashing with another.

https://www.badcaps.net/forum/troubl...-lcfc_nm-c781p[/QUOTErevert

Thanks for your reply.
Yes as mentioned above, I did reflash Ec and Main Bios with a dump from Lenovo support to no avail. Will try the bin you posted and revert.

Flashed EC with the .bin file you posted didn't help triggering. found particularly pch_pwr_en = 0V. ?? So I Reflashed Back Ec with Lenovo support dump and got pch_pwr_en = 2.44V

[kamel]

Both +1.8V and +1.05V rails are enabled by PCH_PWR_EN which in turn is issued by SIO. It should be 3.3V and not 2.4-2.5V

Measure PCH_PWR_En on SIO pin-is it 2.4V there? If yes, remove PR506/507 one by one to see if it rises to 3.3V.

Yes, it's 2.4V. PR506 and PR507 are pads, and needed to be cut. I will post an update.

[kamel]

Update and summarize: new voltages found (see annotations on the 2 attached documents). PBTN_OUT # steady +2.44V ??(doesn't pulse to low). CS# pin steady 0V?? Issue Laptop not trigger. +1.8VALW is absent ?? and +1.05VALW found 0.33V ?? H_PROCHOT# is low 0.28V ?? but Motherboard doesn't get hot. What steps do you suggest to dig further ? Thanks.

[kamel]

Update : CS# pin of Bios UC702 (MXIC 25L12872F) is now +3.2V

[mcplslg123]

Did you cut PR506/507 tracks to check whether PCH_PWR_EN rises to 3.3V or not?
EC_ON at 2.8V also seems a bit low to me.

[kamel]

Did you cut PR506/507 tracks to check whether PCH_PWR_EN rises to 3.3V or not?
EC_ON at 2.8V also seems a bit low to me.

I did cut the tracks and PCH_PWR_EN unfortunately didn't rise still +2.4V. Would a non proper dump or a bad EC Chip causing the issue?

[mcplslg123]

PCH_PWR_EN is totally isolated after cutting tracks of PR506/507. To me it seems like bad EC and /or bad ec firmware.

Keep the tracks at those two resistors disconnected and inject 3.3V on the LV IC side and check whether you get stable 1.8V/1.05V.
This will make us sure whether LV ic is creating problem or EC itself. Ultimately it could be even bad SOC. So keep digging.

[kamel]

PCH_PWR_EN is totally isolated after cutting tracks of PR506/507. To me it seems like bad EC and /or bad ec firmware.
Keep the tracks at those two resistors disconnected and inject 3.3V on the LV IC side and check whether you get stable 1.8V/1.05V.

Thanks for your suggestion and sorry for my late feedback. Injecting 3.3V simulating PCH_PWR_EN didn't help. 1.05VALW and 1.8VALW are still failing.

[QUOTE=This will make us sure whether LV ic is creating problem or EC itself. Ultimately it could be even bad SOC. So keep digging.[/QUOTE].
So the new installed LV ic is failing. ??. In this case I wish to solve the non trigging issue before replacing LV Ic. Though 1.05VALW and 1.8VALW must be present at S5 state, I guess they are not needed for just turning on laptop. Do you agree ? If yes, then PBTN_OUT# always 2.44V and EC_RSMRST# always 0.1V issues are caused either by bad dump or bad IT8586E chip ? Your comment is welcome.

[mcplslg123]

The mb will very like not trigger without LV ic. At this stage i'm not sure whether its LV IC thats bad or is it a bad SOC pulling down those 1.05/1.8V rails.

If you have another LV IC at hand ,its worth trying replacing it.

However, in most cases when these LVXXX multi regulator fails on lenovo's,SOC goes bad. This view is from practical work experience..

[kamel]

The mb will very like not trigger without LV ic. At this stage i'm not sure whether its LV IC thats bad or is it a bad SOC pulling down those 1.05/1.8V rails.

If you have another LV IC at hand ,its worth trying replacing it.

However, in most cases when these LVXXX multi regulator fails on lenovo's,SOC goes bad. This view is from practical work experience..

Hello, to confirm whether LV IC is faulty or SOC is bad, I desoldered pad PJ504 ((in schematic marked as PR5502) and PJ511 (marked as PR5509) to isolate both outputs +1.05VALW and +1.8VALW from SOC and got 0V outputs. I think LV IC is confirmed to be faulty. You agree ?

From another side PBTN_OUT# +2.44V and not +3.2V, is it more likely a bad dump or bad IT8586E and need replacement ? Please share your point of view. Thanks.

[mcplslg123]

I already said its woth trying a new LV Ic.