ASUS ROG GL752VW-IH74 No power

[birdboy385]

Hey All. I have the forementioned laptop that has no signs of life when plugged in. No charge indicator, no power lights, very dead. I got the main board out. I checked power going to the 9 pins on the board where the power jack connects. The first 4 pins read 19.4~ V, the 5th pin has nothing which makes sense since it's unused, the other 4 pins are grounded. I was trying to find a schematic to see if that's what it should be, but couldn't find anything. I also unplugged everything else from the board to try eliminating any additional shorting points. Does anyone have any suggestions on where to proceed next?

[JuniorEmard]

Hey All. I have the forementioned laptop that has no signs of life when plugged in. No charge indicator, no power lights, very dead. I got the main board out. I checked power going to the 9 pins on the board where the power jack connects. The first 4 pins read 19.4~ V, the 5th pin has nothing which makes sense since it's unused, the other 4 pins are grounded. I was trying to find a schematic to see if that's what it should be, but couldn't find anything. I also unplugged everything else from the board to try eliminating any additional shorting points. Does anyone have any suggestions on where to proceed next?getting over it

It seems like the power jack on your laptop may be faulty. Pin 1 - SLEEVE TERMINAL, Pin 2 - SHUNT TERMINAL and Pin 3 - TIP TERMINAL 2. The first 4 pins on your board read 19.4~ V, the 5th pin is empty and the remaining 4 pins are connected land. It's possible that the SHUNT terminal is not working correctly and this could be causing the problem.

[birdboy385]

It seems like the power jack on your laptop may be faulty. Pin 1 - SLEEVE TERMINAL, Pin 2 - SHUNT TERMINAL and Pin 3 - TIP TERMINAL 2. The first 4 pins on your board read 19.4~ V, the 5th pin is empty and the remaining 4 pins are connected land. It's possible that the SHUNT terminal is not working correctly and this could be causing the problem.

I'm assuming that the shunt terminal shouldn't be reading 19.4V then?

[mcplslg123]

Since you have 19V on dc jack,check whether it reaches the CLR after 2 dc-in fets.

[birdboy385]

Since you have 19V on dc jack,check whether it reaches the CLR after 2 dc-in fets.

Umm...any chance you can guide me to where that'd be. I'm not super skilled on indepth electronics. I can upload better pics if necessary as guidance.

[mon2]

Yes. Post clear pics of the top and bottom side of the logic board where the power enters the board. You should see (usually) 2 x mosfets. These are the tiny 8 pin devices with 4 pins on each side. They act like solid state relays. On 8 pin packaged devices, pins 1-2-3 are the source pins. Pin #4 is the gate. Pins 5-6-7-8 are the drain pins.

The part has a polarity so search for pin #1 which will often be identified with a dimple (dot) on the top side.

search for a datasheet to understand the pin out of the device.

we are after the voltage to ground on the source pin; gate pin; drain pins. Repeat for the 2nd mosfet. Measure carefully.

post all measurements.

these mosfets will be driven by a charger ic. We want a clear picture of the charger ic.

how this all works is very well documented by piernov in the above sticky. It is a must read.

[birdboy385]

So I found a similar thread for the board I have. They included a boardview of the 2.0 board, whereas I have the 2.1 This is where things get a bit complicated. The layout is a bit different than mine. In the boardview picture I verified voltage / ground and the A/D_DOCK_IN voltage on the PL600x chips . The A/D_DOCK_IN leads to other chips that don't match my board. I included a picture of my charging area the best I could. There's a lot of residue from the adhesive. If I had to assume, the 2 black chips near the 2R2s are the MOSFETS.

I wasn't sure what I was looking for on the profile.






Thread - https://www.badcaps.net/forum/troubl...-boardview-plz

[mon2]

See attached.








Remove all power. Meter in resistance mode.

Measure the resistance across each of these mosfets as follows:

source (1-2-3) & drain (5-6-7-8) ; these pins will be shorted on the board so pick anyone
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement for each mosfet. Likely one of the mosfets is defective / leaking. You are testing the mosfets PQ8900 and PQ8901 from the schematic.

[birdboy385]

source (1-2-3) & drain (5-6-7-8) - 163K Ohms on both mosfets
source (1-2-3) & gate (4) - 4.2 - 4.3M ohms on both mosfets across all 3 source pins and the gate
gate (4) & drain (5-6-7-8) - 1M ohms on the lower mosfet on each drain pin 1.1M Ohms on the other on each pin.

[mon2]

source (1-2-3) & drain (5-6-7-8) - 163K Ohms on both mosfets

This measurement is considered to be low for a mosfet. Suggest to flux and carefully remove one of the mosfets. Pick either one to get started. Then allow it too cool down and measure the removed mosfet again when it is on your work table. If the resistance remains to be low for the above source / drain measurements, it should be replaced. Continue to test the next mosfet for the same issue.

reference:

How to Know if MOSFET is Defective | ElectronicsBeliever