LENOVO G50-70 /ACLU1 ACLU2 /No power dead

Hi
laptop doesn't show sign of life , no led ,no power , no charging.

I tried other bios nothing change
I checked on UC3 there's 0v
I checked PQ301 there's 20.33v on all pins
I checked PQ302 there's 20.33v on pin 1 to 4 and 0.8v on pin 4 to 8.

Can you help me please , what i have to check ?
Best regards

measure resistance on data of all usb

PU401 or PU402 is hot?

gs84 писал(а):measure resistance on data of all usb

Hi ,
resistance data with ground is 185 KΩ

kmro16 писал(а):PU401 PU402 ou est chaud?

Hi
Sorry but there's no PU401 and PU402

Best regards

resistance data with ground is 185 KΩ

on all data's (USB 2.0 and USB 3.0)?
what the exact MB model? ACLU1 ACLU2 - this is not model.

Guys, PQ301 & PQ302 are P-chanell mosfets. 20,33V on gates is simply incorrect.
Sebuncle please measure the resistance on PQ302 drain. If shortcut is present please make the shortcut test. If not please change PQ301 & PQ302.

gs84 писал(а):

resistance data with ground is 185 KΩ

on all data's (USB 2.0 and USB 3.0)?
what the exact MB model? ACLU1 ACLU2 - this is not model.

Hi yes on all ports
motherboard is NM-A272

dominik555 писал(а):Guys & PQ301 PQ302 sont MOSFET P-Chanell. 20,33V sur portes est tout simplement inexact.
Sebuncle s'il vous plaît mesurer la résistance sur la fuite PQ302. Si raccourci est présent s'il vous plaît faire le test de raccourci. Sinon s'il vous plaît changer et PQ301 PQ302.

pin 4 of PQ302 have no resistance with ground (OL)
So i have to change PQ301 and 302 ?
Can you explain , what is the shortcut test please ?

Best regards

Here is description: szkolenie-nr-1-podstawy-diagnostyki-plyt-glownych-laptopow-t986.html

A short-test can now be performed. Laboratory power supply must be used for that test, because the standard laptop's charger switches off in case of a shorted circuit.
Short-test involves connecting a voltage to the Drain pin of the PQ1 transistor from the laboratory power supply. Starting with 1V and 500mA should last, but it can be set to higher values if needed (but, only in 19V main power rail!). Short-test should be carried on cold board. After a short while a faulty component, usually a capacitor should heat up and can be found either by simply touching it or by using a multimeter with a thermocouple. After removing and replacing the offending component the board usually starts to work properly. If not we continue with the short-test until all shorted components are found and replaced.

There are two main points to notice when performing a short-test:
1. In case when heat can be felt on the core of either of the bridges or graphics card, short-test should be immediately stopped. In this cases usually one of the transistors working with the DC controller is shorted and there is a risk of connecting high e.g. 19V voltage directly to the bridge or graphics card which are usually powered by 1V to 5V voltage. In this case you can't tune up the voltage above value, which is normally operated in lower values (for example, for the 1,8V power rail you can tune up the voltage only to 1,8V value maximum!).
2. Second thing is that the short-test with 19V (usual laptop power supply voltage) can be carried only in case of shorts in main VIN voltage rails. Such voltage CAN'T be connected to any voltage controller inductors, because there is a risk of a serious damage or even blown component.

Yes, change PQ301 and PQ302.

dominik555 писал(а):Guys, PQ301 & PQ302 are P-chanell mosfets. 20,33V on gates is simply incorrect.
Sebuncle please measure the resistance on PQ302 drain. If shortcut is present please make the shortcut test. If not please change PQ301 & PQ302.

Hi,
i change PQ301 and 302 , so laptop start !
thank you very much
Best regard