Asus Nitro 5 N20C1 dead

[BalkanBoy]

Re: Asus Nitro 5 N20C1 dead

Check CPU and GPU capacitors, I marked them on your photo. In most cases they go bad, usually CPU ones but I bet that on your motherboard could be GPU as well. That poor laptop was tortured.

I also do gaming on laptops but I always watch the temperatures and I lower the details or undervolt if possible, but you are obviously always above 90 degrees, at least your board looks like it.

[vpower]

Re: Asus Nitro 5 N20C1 dead

Just checked, all the caps you marked are shorted to ground on both sides. Every single one.

[mon2]

Re: Asus Nitro 5 N20C1 dead

Use the lowest resistance scale on your meter. Remove all power.

Check the resistance again using this setting. It is possible that the resistance is low as it is a low voltage rail. Post your readings.

[vpower]

Re: Asus Nitro 5 N20C1 dead

you mean the capacitors? in ohm mode I measure 1,9 - 2,0 ohm in every cap. The lowest scale on my meter is set in 200 ohm

[BalkanBoy]

Re: Asus Nitro 5 N20C1 dead

Just checked, all the caps you marked are shorted to ground on both sides. Every single one.

Not all, just one is shorted but they are all parallel.
Remove 2 biggest one under gpu and check them off the board, the 2 ones that looks most brownish. That part looks dodgy to me. If those are not shorted continue removing others till you find wich one is shorted.

That's wrong way but maybe the only way since you got no proper equipment.

[Sephir0th]

Re: Asus Nitro 5 N20C1 dead

It's a Gaming Laptop, so you're very likely dealing with a shorted high side. First put the current sense resistors back if not already done and then Check resistance between PRB3 and each coil on your board. Share the two lowest readings you get here, with coil designation. Good luck.

[vpower]

Re: Asus Nitro 5 N20C1 dead

A little update about this repair.
First of all, thanks everybody for the help provided.
I finally bought a thermal camera and I found a shorted capacitor. You can see it, highlighted in the attached image. I removed it (without replacing), no more shorts, very nice
I reassembled the laptop and tested. It is turning on but there is another problem: the laptop will not charge above 4%.It turns on,it stays on, even without battery, but with the battery I see the charging icon but no more than 4% after hours f charging.
With the charger plugged in,on pin 7 and 8 of battery connector PJP201 I have:
0.23v without the battery
14.5v with the battery
Maybe this problem is easier...any hint?
Thanks in advance.

[mon2]

Re: Asus Nitro 5 N20C1 dead

Remove all power. Remove the battery.

Meter in DIODE mode.

Red meter probe, yes red to ground.
Black meter probe to the point to test.

Test each point on the battery connector.

Specifically interested in the SMBUS interface lines on the battery connector. It is possible the smbus lines are defective due to an ESD event which nukes the ESD tvs diode(s).

Post each measurement.

[vpower]

Re: Asus Nitro 5 N20C1 dead

from the left to the right:

pin 1 and pin 2 shorted to ground
pin 3 .543
pin 4 .592
pin 5 1.064
pin 6 .492
pin 7 and pin 8 .520

[mon2]

Re: Asus Nitro 5 N20C1 dead

These are good readings.

Is the battery partially charged? Is the battery pack able to power the laptop without the use of the external power adapter?

The next suggestion is to attach the battery and power adapter.

Then with extreme care, measure the voltage to ground of each pin on the charger IC @ PUB1.

Curious on the key pin voltages such as:

ACDET
ACDRV
REGN
ACOK

(with the battery & external power adapter connected)

Post each measurement.

Update:

Do also measure the voltage to ground of the battery connector pins with the battery & external power adapter mated to the logic board.

Post these readings.

[vpower]

Re: Asus Nitro 5 N20C1 dead

the battery, when disconnected, has 0v measuring black and red.the laptop will not boot without the charger. with the charger it will boot and battery will be stuck at 4%

with both battery and charger connected,these are the readings on battery connector:
pin 3 to gnd 3.23v
pin 4 to gnd 3.23v
pin 5 to gnd 0.16v
pin 6 to gnd 0v
pin 7 & 8 to gnd 14.49v

tested without microscope but I thinc readings are correct:

ACDET 2.62v
ACDRV 0.10v
REGN 5.97v
ACOK 3.26v

[mon2]

Re: Asus Nitro 5 N20C1 dead

ACDRV is not working. Often is the fault of the 2nd dcin mosfet. Please review the sticky article above by @Piernov.

Remove the 4k resistor on the ACDRV pin. Power up again. Then measure the ACDRV pin directly on the charger IC. Suspect is that the 2nd DCin mosfet is leaky.

You can check the mosfet by removing all power and checking the resistance across the mosfet pins. Search this forum for the details. This website should be renamed to badchargers.net. A low mosfet reading means the mosfet is defective.

[vpower]

Re: Asus Nitro 5 N20C1 dead

ACDRV is not working. Often is the fault of the 2nd dcin mosfet. Please review the sticky article above by @Piernov.

Remove the 4k resistor on the ACDRV pin. Power up again. Then measure the ACDRV pin directly on the charger IC. Suspect is that the 2nd DCin mosfet is leaky.

You can check the mosfet by removing all power and checking the resistance across the mosfet pins. Search this forum for the details. This website should be renamed to badchargers.net. A low mosfet reading means the mosfet is defective.

you mean remove PRB7 and check PQB12, right? sorry I'm a noob

[vpower]

Re: Asus Nitro 5 N20C1 dead

the battery, when disconnected, has 0v measuring black and red.the laptop will not boot without the charger. with the charger it will boot and battery will be stuck at 4%

with both battery and charger connected,these are the readings on battery connector:
pin 3 to gnd 3.23v
pin 4 to gnd 3.23v
pin 5 to gnd 0.16v
pin 6 to gnd 0v
pin 7 & 8 to gnd 14.49v

tested without microscope but I thinc readings are correct:

ACDET 2.62v
ACDRV 0.10v
REGN 5.97v
ACOK 3.26v

please ignore the reading about ACDRV. sorry. the correct reading is 19.81.
so I'm stuck...what do you think?
I also have a noob question about PRB3 and PRB46: since I desoldered and soldered back, I see on the diagram that those resistor have 4 pins each but I only see two, as a normal resistor. did I make something wrong?

[Sephir0th]

Re: Asus Nitro 5 N20C1 dead

When ACDRV is reading 19V, one of your DC-IN Mosfets is internal shorted. Usually the second one. For N-Channel Mosfets Correct voltage would be around 25V at ACDRV.

[vpower]

Re: Asus Nitro 5 N20C1 dead

When ACDRV is reading 19V, one of your DC-IN Mosfets is internal shorted. Usually the second one. For N-Channel Mosfets Correct voltage would be around 25V at ACDRV.

thank you. you mean the little mosfet named PQB12 right?

[Sephir0th]

Re: Asus Nitro 5 N20C1 dead

First, remove power and confirm short between Source and Gate (or Drain and Gate). Then remove PQB12 and check at the other Mosfets (or empty pads where second mosfet belongs) whether the short persists or whether it is gone. If it is gone, replace it with a suitable one.

[vpower]

Re: Asus Nitro 5 N20C1 dead

First, remove power and confirm short between Source and Gate (or Drain and Gate). Then remove PQB12 and check at the other Mosfets (or empty pads where second mosfet belongs) whether the short persists or whether it is gone. If it is gone, replace it with a suitable one.

PQB12 has no shorts . instead, PQB11 (the first and bigger one) is shorted between pins 123 and 5678. I'm removing it and check if short is gone