Acer Nitro 5 N20C1 no power no charging

[redoxy]

Re: Acer Nitro 5 N20C1 no power no charging

Just an update and hopefully, one of the experts here can confirm my conclusion or point me in the right direction.

I read through lots of threads on this forum regarding the diagnosis of bad/shot CPU and some of the common questions are in relation to the inductor resistance reading after lifting one side off the board.
Unfortunately, in the threads I read, the numbers were not posted.

I followed those instructions and lifted one side of the CPU inductors. I have shown the ones I lifted in the red rectangle numbered 1-4 in the attached picture.

Below are the resistance reading the "front" refers to the side further away from the CPU as in the picture and the "back" refers the closer to the CPU as in the attached picture:

1. Front = 0.836k Ohms and back = 1.3 Ohms
2. Front = 0.836k Ohms and back = 1.1 Ohms
3. Front = 0.843k Ohms and back = 1.1 Ohms
4. Front = 0.822k Ohms and back = 1.2 Ohms

Based on these measurements, I am concluding that the CPU is shot/bad.
Is this an accurate conclusion?

Thanks in advance.

[mcplslg123]

Re: Acer Nitro 5 N20C1 no power no charging

Seems like a gaming board with "H" Cpu. So resistance close to 1 ohms should be fine.

[rediii]

Re: Acer Nitro 5 N20C1 no power no charging

Just an update and hopefully, one of the experts here can confirm my conclusion or point me in the right direction.

I read through lots of threads on this forum regarding the diagnosis of bad/shot CPU and some of the common questions are in relation to the inductor resistance reading after lifting one side off the board.
Unfortunately, in the threads I read, the numbers were not posted.

I followed those instructions and lifted one side of the CPU inductors. I have shown the ones I lifted in the red rectangle numbered 1-4 in the attached picture.

Below are the resistance reading the "front" refers to the side further away from the CPU as in the picture and the "back" refers the closer to the CPU as in the attached picture:

1. Front = 0.836k Ohms and back = 1.3 Ohms
2. Front = 0.836k Ohms and back = 1.1 Ohms
3. Front = 0.843k Ohms and back = 1.1 Ohms
4. Front = 0.822k Ohms and back = 1.2 Ohms

Based on these measurements, I am concluding that the CPU is shot/bad.
Is this an accurate conclusion?

Thanks in advance.

in my opinion it's a little low... should be around 3-6 ohms in most cases for an intel cpu. but i could be wrong though

[redoxy]

Re: Acer Nitro 5 N20C1 no power no charging

Thanks, mcplslg123 and rediii for the response.

Yes, it is a gaming board with a Core i5 10300H CPU.

[redoxy]

Re: Acer Nitro 5 N20C1 no power no charging

I'd like to once again thank everyone for their input and direction.

At this stage I think I am throwing in the towel and concluding that the CPU is shorted.
I watched a video on YouTube and the guy seem very knowledgeable.

Around 20:11 min he discusses how to check for shorted CPU using a capacitor and the CPU inductors. I did the same measurements on the board and resistance was 0.0 Ohms, which he said points to shorted CPU.
This conclusion is me just blinding trusting the video. If any of the experts here think that is not a reasonable conclusion, kindly point me in the right direction.

Cheers!

[redoxy]

Re: Acer Nitro 5 N20C1 no power no charging

Another update. Apologies ahead for the long post but I wanted to give as much information as possible so I can get the right help.

After deciding it was a shorted CPU based on the YouTube video I liked earlier, I watched another YouTube video from another popular repair shop on YouTube (I will leave unnamed as some people will cringe ). The issue he was addressing was very similar to what I was seeing. However, his was on the GPU side.
He seemed certain the shot wasn't the GPU, even when during voltage injection the GPU was getting hot. He said it was likely the power MOSFET was the shorted part and also said some MOSFETs are good at dissipating their heat so hard to tell with just voltage injection when they are shorted.

With that I decided to test my board again and removed PLZ1 to PLZ4 inductors and retested. It pointed to a shorted MOSFET (PQZ1). I desoldered that MOSFET and there wasn't a short anymore. Bench tested the MOSFET and it was indeed shorted.

I replaced the inductors and the MOSFET with new ones and tested for shot to ground and there was no short.
I plugged in the charger and charging light came on. I turned on the laptop and the power indicator as well as the keyboard lights also came on.

However, the display isn't working.

Here are some things I have tried so far:
1. Connected an external monitor/display and still no display
2. I tried resetting BIOS (power off, disconnected main and BIOS batteries and hold power button for at least one minute) did not help either.
3. Tried plugging in external USB keyboard and the number light doesn't come on when plugged into all three USB ports.
4. Checked the display connector and plug for possible damaged and couldn't find any.
5. Tried multiple working RAM sticks and same result.

Additional notes is that the CPU and GPU fans spins for a few seconds when powered on then stops but after leaving it on for a few minutes, both fans kick on again.

The battery charges fine (fully charged battery for testing and all was good) and laptop powers on with power adapter as well as battery with the same behaviour. When powered on with power adapter and then the power adapter is removed, it makes the notification sounds for when power plug is removed.

Any help on what could be wrong or what next steps to take?
Happy to take any measurements that may help diagnose the issue.

I am reattaching the schematics to this post for convenience.

Thanks in advance

[Sephir0th]

Re: Acer Nitro 5 N20C1 no power no charging

It's a classical case of a so called "high-side short". In your case the main power rail was shorted with The VCC_CORE supply.

The most bad news here that almost no CPU survives this kind of failure. For this reason you still can't get it back working even after replacing the shorted Dual-Mosfet. And probably still the same when you replace the whole buck converter (Controller, all driver, all Mosfets) as it is strongly suggested in such cases.

[kjchatman]

Re: Acer Nitro 5 N20C1 no power no charging

i have this same board and it has a short on 3valwp. when i removed the platform hub cntroller then it went away so i bought a brand new pch and put it on the board and the short came back.

[redoxy]

Re: Acer Nitro 5 N20C1 no power no charging

It's a classical case of a so called "high-side short". In your case the main power rail was shorted with The VCC_CORE supply.

The most bad news here that almost no CPU survives this kind of failure. For this reason you still can't get it back working even after replacing the shorted Dual-Mosfet. And probably still the same when you replace the whole buck converter (Controller, all driver, all Mosfets) as it is strongly suggested in such cases.

Thanks, Sephir0th for the input.
Obviously not what I was hoping to hear and got really excited from seeing the results after replacing the shorted dual-MOSFET.

Since the CPU is dead, and there is almost no way of getting another CPU even if it was possible to replace it, that's the end of the road for this project.

It was a good learning experience for me.

Thanks again to all for the help and input.

Cheers!!

[redoxy]

Re: Acer Nitro 5 N20C1 no power no charging

i have this same board and it has a short on 3valwp. when i removed the platform hub cntroller then it went away so i bought a brand new pch and put it on the board and the short came back.

@kjchatman
I think you are more likely to get responses and the help you need if you start a new thread.