Lenovo ideapad 1 14|GL05 No display

[senakahks]

I am trying to fix Lenovo ideapad 1 14|GL05 (Wistron LS1511G 19705-1M).

When I press the power button its bulb turns on. But no display. When I keep the button pressed for a while. It goes off.

I have the following rails working

3.3V
5V
1.2V
The big coil (PL4701) which should be the CPU power supply doesn't produce any voltage. 19V is coming to the MOSFET.

The microprocessor is not getting warm and no display. Is bios signal needed to power on CPU/GPU vcore?

I flashed the bios but had no success. Please support me to go ahead. Thanks!

[mcplslg123]

Re: Lenovo ideapad 1 14|GL05 No display

If schematic is available please post or link it.
What is the resistance to GND on vcore coils(likely two coils for vcore and another coil for GFX)?
Alot many rails need to come up before vcore appears on motherboard,eg,VCCSA/1.8V/2.5V.

[senakahks]

Re: Lenovo ideapad 1 14|GL05 No display

If schematic is available please post or link it.
What is the resistance to GND on vcore coils(likely two coils for vcore and another coil for GFX)?
Alot many rails need to come up before vcore appears on motherboard,eg,VCCSA/1.8V/2.5V.

Resistance to the ground is 205 Ohms.
An Image of the motherboard and schematic are attached herewith.

MOD Edit: Schematic -> https://www.badcaps.net/forum/showthread.php?p=1261114
Reminder: rules and organization of this section -> https://www.badcaps.net/forum/showthread.php?t=117483
.

[barry7]

Re: Lenovo ideapad 1 14|GL05 No display

My Lenovo is doing the same thing, I found a fried IC going to the lcd, apparently this is an issue with their laptops. It’s usually under the U9 slot. I’m not sure how if effects everything else but it does. I’m trying to identify what mine is because it’s not readable.

[senakahks]

Re: Lenovo ideapad 1 14|GL05 No display

My Lenovo is doing the same thing, I found a fried IC going to the lcd, apparently this is an issue with their laptops. It's usually under the U9 slot. I'm not sure how if effects everything else but it does. I'm trying to identify what mine is because it's not readable.

I tried to locate U9 to check whether I can read the number. Can you please send a photo of the location?

[mcplslg123]

Re: Lenovo ideapad 1 14|GL05 No display

@senakahks, you have not shared the measurements for 1.05V/1.8V/2.5V/VCCSA etc.

[senakahks]

Re: Lenovo ideapad 1 14|GL05 No display

@senakahks, you have not shared the measurements for 1.05V/1.8V/2.5V/VCCSA etc.

PL4501 - 3.3V
PL4551 - 5V
PL4401 - 8.1V
PU5102 - 1.2V
PL4701 - 0V

Some other voltages were measured.
0D6V_S0 - 0.6V
1D05V_S0 - 1.05V
1D8V_S5 - 1.8V
1D2V_S5 - 1.05V

[senakahks]

Re: Lenovo ideapad 1 14|GL05 No display

Some other reading I got is given below. I took them since there are test pads near the power management chip
May be useful for an expert to advise me.

ALL_SYS_PWRGD: 2.8V

At BD2761MWV
PCH_PWROK: 2.7V
RSMRST_B: 3.3V
PWR_EXTMODE: 0V
PWR_EXTMODE2: 0V
SLP_S0_B: 3.3V
SLP_S3_B: 3.3V
PMIC_EN: 0V
PWR_DATA: 1.8V
PWR_CLK: 1.8V
PWR_IRQ_B: 1.8V
VCCGI_CSP: 0V
VCCGI_DRIVEN: 0V
VCCGI_FBN: 0V
VCCGI_FBP: 0V
PWR_VDDQ_CSP: 1.7V

[senakahks]

Re: Lenovo ideapad 1 14|GL05 No display

ALL_SYS_PWRGD: 2.8V

PCH_PWROK: 2.7V

Are these values acceptable as 3.3V?

[mcplslg123]

Re: Lenovo ideapad 1 14|GL05 No display

PMIC_EN voltage is wrong. Its derived from 3v_5V_PWRGD,so check whether its present or not.PU4601,pin30 voltage? All_sys_pwrgd is derived from PMIC_pwrgd which in turn is derived from pch_pwrok. The pull up used is 3.3V,so logically speaking it should be 3.3V.

1D2V_S5 - 1.05V as per your post#7.Should be 1.2V.

[senakahks]

Re: Lenovo ideapad 1 14|GL05 No display

PMIC_EN voltage is wrong. Its derived from 3v_5V_PWRGD,so check whether its present or not.PU4601,pin30 voltage? All_sys_pwrgd is derived from PMIC_pwrgd which in turn is derived from pch_pwrok. The pull up used is 3.3V,so logically speaking it should be 3.3V.

1D2V_S5 - 1.05V as per your post#7.Should be 1.2V.

I checked the voltages again.

My bad PMIC_EN is 3.24V
Pin 30: 1.5V
PCH_PWRGD: 2.7V

[mcplslg123]

Re: Lenovo ideapad 1 14|GL05 No display

These measurements looks good to me. I've seen All_SYS_PWRGD at this value on some working boards-so may be its correct. Is the ram soldered or is there a slot?

Voltage on these coils please
PL5103
PL5001/2/3/4

[senakahks]

Re: Lenovo ideapad 1 14|GL05 No display

These measurements looks good to me. I've seen All_SYS_PWRGD at this value on some working boards-so may be its correct. Is the ram soldered or is there a slot?

Voltage on these coils please
PL5103
PL5001/2/3/4

PL5103: 1.8V
PL5001: 1.05V
PL5002: 1.05V
PL5003: 1.05V
PL5004: 1.05V

Normally I took all reading while the battery and main power are connected.

No ram slots and all are onboard other than WLAN card.

Appreciate your time.

[senakahks]

Re: Lenovo ideapad 1 14|GL05 No display

The main power IC here is BD2670MWV. What are the essential signals and voltages I have to check to figure out why VCCGI_DRVEN is not high? Really complicated issue for a beginner.

[Kamile523]

Is anyone managed to fix no screen problem?