Lenovo Z570 - no image

[sicilianul]

Hello,

I have 3 mb's Lenovo z570 ( 10290-2 48 44pa01 021 LZ57 )

2 of them are auto-power on. I have only 1 vcore wich is initialy 1.1v and after ~1sec is 0.6v and after 3 sec is powering off. Bios is ok, memory 1.5v, video 1v tested with 3 processors, 3.3v and 5v are ok.

Another mb has a strange sinusoid on video power supply. see here https://ibb.co/bdMWFs1

Do you have any ideas?

[Techtiger]

Re: Lenovo Z570 - no image

rest of the coil voltages are ok ? resistance on PL4101 PL4102
test VCC CORE VCC GFXCORE
1D8V VGA
3D3V VGA
1V VGA

[sicilianul]

Re: Lenovo Z570 - no image

Hello, after 1 year I've managed to repair one of the motherboards. Problem was PU4307 which was heating excessively, after I've removed - the pads was on fire. Changed also the PU4306 - shortcircuit between PIN 7 and PIN 8.

Now - the second motherboard is same design as first. Next voltages are powering up: 3.3, 5v, 1.5memory.

But I have a small problem: VCC GFXCORE isn't powering up. PU4405 has PIN2 PWM very low ~2v without oscilation. PWR_CPUCORE_PWMA is coming from PU4201 and I have allready change it, but no effects. Any idea?