Acer Nitro 5 motherboard no power (FH52M LA-J891P)

[mcplslg123]

Re: Acer Nitro 5 motherboard no power (FH52M LA-J891P)

I beleive Dramrst# is pulled high or low by cpu and not Pch.

[aico60]

Re: Acer Nitro 5 motherboard no power (FH52M LA-J891P)

Both CPU and PCH are getting slightly hot when I power the laptop on and I am getting the PLT_RST at 3.3V.

I am thinking if a bad EC chip can cause those symptoms, anyone familiar with this?

Also, as I mentioned in my previous update:
Measured some pins of PUG1 (attached screenshot):
pin 1 - 5V
pin 3 - 4.8V
pin 5 - 0V
pin 7 - 0V
pin 8 - 0V

The VCCGT voltage is missing from the CPU, which I believe is for internal graphics, can this affect the dramrst also?

[mcplslg123]

Re: Acer Nitro 5 motherboard no power (FH52M LA-J891P)

I beleive VCCGT is not related to DramRST#. VCCGT will rise at the very last end of posting. Since DRAMRST# is pulled low, VCCGT cant rise. Most of the times DRAMRST# low is coz of bios but on certain occassions, its the cpu itself and replacing the cpu is the only solution. Thats not an easy job on newer platforms.

[aico60]

Re: Acer Nitro 5 motherboard no power (FH52M LA-J891P)

Hello Guys

After some more tries of reflashing the bios, the dramrst is still not apparent .

I have done some measuring on points RH46 and RH47 (attached screenshots).

What I have noticed is that 1.2V is going to the RH46 resistor, however the output is 0.120V. I am not sure if this is expected, as the output side connects to the PCH and it might be drawing the power, not sure. It seems that the voltage is just disappearing after going through the resistor.

Could you please advise how can I check if the PCH is defective or the CPU?
The PCH is getting pretty hot I would say when the laptop is in On state.

[konter]

Re: Acer Nitro 5 motherboard no power (FH52M LA-J891P)

Good afternoon, I have a laptop Acer Nitro AN515-55-774Z with FM52M LA-J891P Rev 1A. My laptop just turned off and won't turn on again. After applying voltage it simply does not respond. Resistor PRB4 was about 0 volts. I unsoldered the PRB7 resistor to see the changes (picture001.jpg), but after a while PLW3 burned out (picture002). Please tell me what to do.
Thank you.

[Sephir0th]

Re: Acer Nitro 5 motherboard no power (FH52M LA-J891P)

Two simple reasons. First, you missed that some of your DC-IN Mosfets are internal shorted. Second, by messing around with PRB7 you made sure to send 19 volts into the VRAM (because of a internal shorted PQW1) which is supposed to run with 1.35 volts. If not already before, at least now, the whole VRAM and the GPU should be dead. I see no economical way how to continue to be honest.