Lenovo G470 PIWG1 LA-6759P Rev.1.0 (Turn On No Display)

[kodox]

Anyone have bios dump for this mainboard?
i've downloaded from https://www.badcaps.net/forum/showthread.php?t=46758 and flashed with no luck.

Perhaps someone here wanted to check my bios dump

The problem was it shorted to ground on 19v rail caused by mosfet on 1.05VS rail, after replacing the mosfet that power rail become 1.06-1.07 volt and measurement on the coil to ground it's only one ohm, is that normal?

[peste]

Re: Lenovo G470 PIWG1 LA-6759P Rev.1.0 (Turn On No Display)

try...

[kodox]

Re: Lenovo G470 PIWG1 LA-6759P Rev.1.0 (Turn On No Display)

it still the same my friend, no display. thx for helping

[Francisco.s]

Re: Lenovo G470 PIWG1 LA-6759P Rev.1.0 (Turn On No Display)

The problem was it shorted to ground on 19v rail caused by mosfet on 1.05VS rail, after replacing the mosfet that power rail become 1.06-1.07 volt and measurement on the coil to ground it's only one ohm, is that normal?

If 1.05 rail have been received 19v before mosfet got short-circuited, then probably cpu or pch are damaged for sure.

[kodox]

Re: Lenovo G470 PIWG1 LA-6759P Rev.1.0 (Turn On No Display)

@Fransisco.s, that's what i thinked of, but since the mainboard uses zif socket for the processor i can tested it on other mainboard and it still worked. so i think i should try to replace the pch now. thank's for helping...

[mcplslg123]

Re: Lenovo G470 PIWG1 LA-6759P Rev.1.0 (Turn On No Display)

@Fransisco.s, that's what i thinked of, but since the mainboard uses zif socket for the processor i can tested it on other mainboard and it still worked. so i think i should try to replace the pch now. thank's for helping...

Schematic is available. Have you checked all signals?? Going by LA-6752p schematic ,there is power sequnce given on pg 47.Just a word of caution before replacing pch.

[kodox]

Lenovo G470 PIWG1 LA-6759P Rev.1.0 (Turn On No Display)

Schematic is available. Have you checked all signals?? Going by LA-6752p schematic ,there is power sequnce given on pg 47.Just a word of caution before replacing pch.

The owner of laptop doesn't agree with the price for replacing pch. so he took it that day and i can't tested for it anymore. as far i can remember, no vgfx_core generated but cpu_core at 1v.

anyway, thank's for replying...

[Sultan392]

Re: Lenovo G470 PIWG1 LA-6759P Rev.1.0 (Turn On No Display)

Sorry for the thread necro.

The problem was it shorted to ground on 19v rail caused by mosfet on 1.05VS rail, after replacing the mosfet that power rail become 1.06-1.07 volt and measurement on the coil to ground it's only one ohm, is that normal?

My G470 started having issues while turning on a while back sometimes getting stuck without video output, eventually turning on after many tries. At this time I reflashed both BIOS and EC as I'd tried a modded BIOS once that got rid of the WLAN card whitelist, in case something got corrupted. It seemed to get better for some time but now it just stays there, stuck, no video output.

Seems to be a common issue with this motherboard. All repair related search results for the G470/G570 get resolved by finding the screwed up mosfet or cap and changing it, or fixing the power button. Nothing quite related to what's happening to us, that's why I'm writing here and sorry again for the thread necro.

Kodox, do you remember if by any chance the mosfet you found shorted was PQ901? It's beside the CPU socket, to the left under the heatpipe.



I have vcore at ~1.15v but no +vgfx_core. Turns out PQ901 was completely shorted (gate to source, gate to drain, source to drain, totally destroyed) and this naturally sent 19v straight into the voltage controller and into the CPU/vgfx_core..

vcore is still there and both vcore phases measure well, so the controller can't be dead I guess. Replaced PQ901 with a TPCA8065 as per the schematics (original part was a Vishay Si7686DP), same result, still no +vgfx_core, but at least that mosfet didn't die/get shorted at turn on. Tried a different CPU in case the original got killed, no difference. No shorted caps in that circuit or nearby (it wouldn't even turn on if it were the case I suppose).


I'll check the power up sequence to see what's wrong now, but natural consequence of this failure would seem to be a dead PCH, right?

[djharold]

Re: Lenovo G470 PIWG1 LA-6759P Rev.1.0 (Turn On No Display)

thanks for share and tutorial