Lenovo G50-70 - power on problem

[DeniS182]

Re: Lenovo G50-70 - power on problem

Now I have gpu_core also 1.05VS, CPU_core etc.. fan spinning normally, cpu and gpu heat little bit, but still only black screen.

[MJ-meo-dmt]

Re: Lenovo G50-70 - power on problem

Nice @DeniS182. When you say black screen, not just the back-light that's gone? I mean you tried it on ext display as well I assume?

Sure the RAM is okay?
LVDS connector and power okay?

[DeniS182]

Re: Lenovo G50-70 - power on problem

I looked better and my LCD is going on and off -without backlight, I mean only black picture is here, because I can't see Lenovo logo. LVDS connector looks fine I measured something:
PIN 1 - +LEDVDD = 19.8V
PIN 16 - INVT_PWM = 0V no pwm here
PIN 20 - +3VS = 0V
PIN 21 - +LCDVDD_CON = 0V
PIN 23 - +3VS = 3.3V
PIN 30 - +3VS_CMOS =3.3V
Measured without LVDS cable connected.
Nothing on hdmi output.

[piernov]

Re: Lenovo G50-70 - power on problem

Is it even booting? At least POSTing?

[MJ-meo-dmt]

Re: Lenovo G50-70 - power on problem

I looked better and my LCD is going on and off -without backlight, I mean only black picture is here, because I can't see Lenovo logo. LVDS connector looks fine I measured something:
PIN 1 - +LEDVDD = 19.8V
PIN 16 - INVT_PWM = 0V no pwm here
PIN 20 - +3VS = 0V
PIN 21 - +LCDVDD_CON = 0V
PIN 23 - +3VS = 3.3V
PIN 30 - +3VS_CMOS =3.3V
Measured without LVDS cable connected.
Nothing on hdmi output.

Hmm Interesting... I had something like this not too long ago... Can't remember the make or model.... anyways...

I found a little control circuit on that board that waited for a signal from the PCH to enable or start LED. I never got it to send the signal from the PCH (or EC...) ?? Not sure I'll go check if I can find anything similar in your schematic.
And nothing on HDMI you say? Uhm sounds suspect as well towards the PCH... What about VGA? Also all this assuming the rest of the things work fine (the previous issues)

EDIT: Look at Sheet 33.
signals: PCH_ENVDD | PCH_EDP_PWM | PCH_ENBKL

Check if you get those. Though It could be that you get the signals for a second.. as you said: "my LCD is going on and off" and it goes off again because something else is then causing a halt...

Sheet 4: LCD_BKLT_CTRL_R todo with INVT_PWM

[SMDFlea]

Re: Lenovo G50-70 - power on problem

f you connect the LVDS cable what voltage do you have at pin 20