Lenovo G50-70 - power on problem

[DeniS182]

Hi all,
I have problem with this notebook - is totally dead, no lights, nothing. At first I changed KBC IT8586, because was hot. I ordered programmed chip from ebay. After soldering new chip I found another issue - shorted B+ . Problem was in one shorted capacitor. Now 3.3V and 5v ALW are present. I tried flash bios also. Nothing changed. Now I found bad crystal 27Mhz - YVG1 in schematic. I can't find anything else bad. Can someone help me with this? thanks.

Motherboard: ACLU1/ACLU2 NM-A271
I attached schematic.

[caspian]

Re: Lenovo G50-70 - power on problem

why did you find the crystal faulty? what was wrong with it?

[DeniS182]

Re: Lenovo G50-70 - power on problem

I take photo of the crystal.

[caspian]

Re: Lenovo G50-70 - power on problem

If the crystal is faulty, replace it. Only after that, you can decide on other components.

[DeniS182]

Re: Lenovo G50-70 - power on problem

I order it from ebay. I mean there is another problem.

[DeniS182]

Re: Lenovo G50-70 - power on problem

I replaced crystal with one from another board. Nothing changed.

[homeless_cz]

Re: Lenovo G50-70 - power on problem

Is 3V_ALW_PCH present ? If yes then you have to check what happens on IT8586.
Does it have +3VALW and +3VS ?
Check this in ready state and then after pressing pwr switch:
PWR SW on pin 110
LID SW pin 109
AC present pin 128
PCH_PWR_EN pin 97
PCH_PWROK pin 99
PBTN_OUT# pin 86
MAINPWON pin 79
EC_LID_OUT# pin 2
EC_RSMRST# pin 93

[DeniS182]

Re: Lenovo G50-70 - power on problem

3V ALW_PCH = 3.3V

KBC - 3VALW = 3.3V, 3VS = 0.4V
ready state
PWR SW on pin 110 = 3.3V
LID SW pin 109 = 3.3V
AC present pin 128 = 3.3V
PCH_PWR_EN pin 97 = 0V
PCH_PWROK pin 99 = 0V
PBTN_OUT# pin 86 = 3.3V
MAINPWON pin 79 = 0.3V
EC_LID_OUT# pin 2 = 3V
EC_RSMRST# pin 93 = 0V

after pressing pwr button
PWR SW on pin 110 = 0V
LID SW pin 109 = 3.3V
AC present pin 128 = 3.3V
PCH_PWR_EN pin 97 = 0V
PCH_PWROK pin 99 = 0V
PBTN_OUT# pin 86 = 3.3V
MAINPWON pin 79 = 0.1V
EC_LID_OUT# pin 2 = 3V
EC_RSMRST# pin 93 = 0V

I tried jump Q24 then 3VS=3.3V but still nothing changed.

[homeless_cz]

Re: Lenovo G50-70 - power on problem

This means ITE hasn't met his requirements to power on the system.
LID SW is OK -> LID OUT is OK, AC present is OK. PWR sw is OK.
When you press PWR button, pin 110 goes down and 86 should go down too, then 97 high, 93 high, 79 high and all other SUSP# and SLP# signals should go high too.
Check the same way:
108, 71, 14, 111, 112,
If you have a oscilloscope, you should check pins 101,102,103,105 if there is some communication with SPI flash rom.
Does the laptop at least charge the battery? Is it indicated with charge LED?

[DeniS182]

Re: Lenovo G50-70 - power on problem

Thanks for answer.
ACIN 108 - 0V
VR_CPU_PWROK 71 - 0V
WRST 14 - 3.3V
EC_ON 111 - 3.3V
VSTBY0 112 - 3.3V

I have analog oscilloscope and there isn't any communication.
101 - 3V DC
102 - 0V
103 - 3V DC
105 - 0 V

And no charge light when battery + charger is connected, but I don't know if battery is good.

[homeless_cz]

Re: Lenovo G50-70 - power on problem

Strange.
101 must be 0 to chip select, 103 is data output from SPI chip, 105 is clock for SPI chip
Is SPI chip OK?

Pin 71 is ADP_I from charge controller, shoul not be 0 but analog 0,7 to 2,7V I think depending on charge current.
And pin 80 PROCHOT?
Is ITE well soldered?
Anyway you should check page 53 of schematic. Check all mosfets.

[DeniS182]

Re: Lenovo G50-70 - power on problem

PIN 80 = 0V
SPI chip is ok, I read bin from it.
I tried resolder ITE chip.
All mosfets from site 53 are fine.

[SMDFlea]

Re: Lenovo G50-70 - power on problem

Check ITE pin 72 ADAPTER_ID

[DeniS182]

Re: Lenovo G50-70 - power on problem

pin 72 = 0.3V

[SMDFlea]

Re: Lenovo G50-70 - power on problem

According to this post on elvikom the voltage should be 0.9V with a 65W or 1.4V with 90W charger .Check the middle pin on the DC-IN jack .

https://www.elvikom.pl/lenovo-g50-70...in-t52478.html

[DeniS182]

Re: Lenovo G50-70 - power on problem

I have two 65W chargers and I tried both and value is 0.3V.
Middle pin on the DC-IN jack is fine and on it is 0.3V too.

[homeless_cz]

Re: Lenovo G50-70 - power on problem

PIN 80 = 0V

That's the problem. PROCHOT# is signal of overheated CPU, overheated voltage regulator and under voltage protection. It can't be 0 for normal work.
Check everything related to PROCHOT# and find what generates 0 and blocks normal work.
On page 47 is nice diagram of power-on sequence.

[piernov]

Re: Lenovo G50-70 - power on problem

Missing RSMRST# is more of an issue. Which usually requires the AC adapter identification to work.
EDIT: on HP at least, may be the same on those Lenovo.

[SMDFlea]

Re: Lenovo G50-70 - power on problem

PROCHOT# comes from PU1208 - RT9553A Datasheet:

Should EC_ADAPTER be the same voltage as ADAPTER_ID_ON# ? Check PQ204

[DeniS182]

Re: Lenovo G50-70 - power on problem

PQ204 And PU1208 aren’t on pcb.