Asus Model G501j , Board N501jw short at AC_BAT_SYS

[reformatt]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

Well that's not normal, but the fact it's 1.5 ohms and not a dead short is probably not so good.

Since you have FET's between +19V and the CPU/GPU coils, should be open circuit. A shorted FET means you will have continuity.

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

There is a N channel mosfet just below the ITE at the bottom of board. Was covered with factory tape. Could this be my problem? I measured in diode mode and receive 0.5 on pins 1-3, then 1.7 on pin 4. Short on AC_BAT_SYS. Worth swapping this one out then checking readings again? Am i on the right track?

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

Okay there is an N channel mosfet just below the ITE. I receive 0.5 reading in diode mode, red probe to ground and black to chip pins. I receive this on pins 1 thru 3, then 1.7 on pin 4. Pin 5 is short which is the AC_BAT_SYS line. Should i swap out this chip?

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

Sorry guys it looks like the post doesnt go thru then it ends up going twice.

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

Should i solder the 2nd FET back on just after the DC IN. Just to see if reading change at all? I will leave power off and just play with diode , continuity and ohms.

[reformatt]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

No, you've already established you have a short/low resistance on the +19V rail.

You're checking PL8001~8003 and PL8501~8502 to current sense resistor to eliminate shorted high side FET's.

What FET are you referring to? Low side FET's of buck converters for CPU etc can read low ohms and appear faulty.

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

Okay. No worries. The FET i was referring to was PQ8803. Here are the readings as requested..

PL8001 - 29.1
PL8002 - 29.0
PL8003 - 28.8
PL8501 - 11.6
PL8502 - 11.6

[myth77]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

because you probably dont have lab power supply and thermal camera i would suggest next...its a bit messy but its only way. Remove solder from this joints one by one..end with each solder remove check if short is gone on AC_BAT_SYS line. If not solder back. Use solder wick for removal. Also, check resistance on PL8200 and PL8301.
Solder points to remove:

[reformatt]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

PQ8803 is your BATFET. With battery removed, I can't see how this is your short.

As you have a short on your main rail, anything above 1.5 ohms from the CPU/GPU coils is good. With any luck it'll be a decoupling cap on the main rail. 1V voltage injection should at least draw just below an amp, making it obvious under a thermal camera. If you don't have that, you'll have to rely on your eyes. I look for 0604 or 0805 sized caps near the edge of the board for discolouration/cracking/corrosion. Use voltage injection and bit of IPA to confirm.

And removing the jumpers above is also a good start.

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

Myth77 and Reformatt,
I do have a bench power supply. Can you provide details of what i should try with that? Just inject 1v into the ac_batt_sys rail? And use a thermal camera to see what gets hot? I have freeze spray but nothing heats up that i can tell. That whole rail is pretty much test points on the board.

[myth77]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

the problem is it will be very difficult to trace the short with freeze spray because shorted part will not probably heat that much...but you could try. Inject 1 vol max and set max current to 1 amp...and increase only amps a little if you cant see anything shorted. go steip by step on the board with freeze spray and try to find anything gets hot. And post back how much amp is drawing.

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

I will try that at lunch. What is a good cut off to allow for max amperage? I will start with 1v and 1a and post results of draw.

Thanks!

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

Injected 1v @ 1a to test point for AC_BAT_SYS. Draw was .93 amps. PQ8100 on 3V power rail got hot. Showed up immediately on the thermal cam. Added a drop of IPA on it and it evaporated right away. Havent checked the back of board yet. Will report back shortly. Thanks!

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

Removed PQ8100. Re-injected voltage at AC_BAT_SYS. 0 amp draw now. Short is gone for AC_BAT_SYS. That rail distributes in full. I will resolder PQ8802 now. Looks like the short was on P_3VA_DSW_VIN_S where PQ8100 was connected. Now i found shorted cap on 3VA_EC. Going tp trace this rail now. Will update soon. Thank you for the boost guys! Much appreciated. Not the easiest schematic to follow hehe

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

Looks like i am going to have to do the same thing on each rail. Connect to shorted rail and inject voltage starting with 1v and 1a. Just making sure i am not going to hurt anything on the 3v rail. Thoughts?

[Sephir0th]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

If +3VA_EC is shorted to GND too, then myth77 was probably right from the beginning and the embedded controller was damaged. Turns out more and more issues right now, which doesn't sounds hopeful.

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

If i inject voltage at C3003 on pin 1 (3VA_EC) rail. The only thing that heats up is the ITE. With a .94 amp draw.

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

Sephir0th,
Yeah it sounds like myth77 was correct. Seems like there is everything shorted on this thing. If its the ITE that will need programming correct?

[TheWizard]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

You guys think I should just strip this thing for known good parts and cut my losses at this point?

[mcplslg123]

Re: Asus Model G501j , Board N501jw short at AC_BAT_SYS

You guys think I should just strip this thing for known good parts and cut my losses at this point?

Remove the EC as a last ditch effort and see if all shorts are gone.