Asus tuf fx504gd laptop does not detect dedicated video, only embedded video on scre

[valente222]

Good morning, this is my first post. I have an ASUS TUF FX504GD laptop, the motherboard model is a DABKLGMB8D0 REV D.
The main problem has already been solved, since it was a short in two VIN or VA+ input mosfets (PQ21 and PQ22) before
of the sensing resistors, the PQ37 mosfet was also changed due to rupture of the internal diode.

But now the equipment turns on, video enters the operating system, but there is no activation of the video chip, OS WiNDOWS 10 only recognizes integrated video from the processor.
The coils GPU PL16, PL17, PL18 with voltage of 0.815v

Partially de-voltage coils are PL25 and PL26, so there is no +VCC_GFX
And the coil PL20 +FBVDDQ_MEM without voltage.

Integrated PWM (PU21) has the PGOOD PIN grounded so it does not activate the gates of the PQ37 mosfet. Although the
PWM (PU21) has the ENABLE pin pulled high 3.21v. What could be measured as a reference now?

For this model there is only boardview, not schematic. Bios was also updated but it remains unchanged.

[Sephir0th]

Re: Asus tuf fx504gd laptop does not detect dedicated video, only embedded video on s

The most basic check would be whether +FBVDDQ_MEM is (partial) shorted to GND. PU21 of course won't deassert PGood if it detects a issue, like no Voltage at LX-Pin (PHASE)^^ or other simple faults, like a internal shorted PQ37.

So just check this basics out first before digging more deeper.

[valente222]

Re: Asus tuf fx504gd laptop does not detect dedicated video, only embedded video on s

I understand, I'll check that line again. I check because the PQ37 is a new mosfet there must be a feedback problem or something strange. I will post the result later.

[Sephir0th]

Re: Asus tuf fx504gd laptop does not detect dedicated video, only embedded video on s

You mean, the dual-mosfet was already replaced? Well it can be of course just a bad controller, too. However, as long as we have no measurements, that's only guessing.

[valente222]

Re: Asus tuf fx504gd laptop does not detect dedicated video, only embedded video on s

Yes, Mr. Sephir0th. I'm going to check those LX lines to see what the problem is. but I doubt it's the mosfet but I'll take it out and try it. About the measurements that you say, am I going to measure something before pwm PU21 of this circuit?

[Sephir0th]

Re: Asus tuf fx504gd laptop does not detect dedicated video, only embedded video on s

I see. Multimeter in Ohms mode, range 200 or auto-range, red probe to the coil connected to PQ37, black probe to GND. Share the measurement, pls

[valente222]

Re: Asus tuf fx504gd laptop does not detect dedicated video, only embedded video on s

my multimeter's absolute zero is 0.7 ohm measuring the LX output from the mosfet to the coil is 2.2ohm average.

[myth77]

Re: Asus tuf fx504gd laptop does not detect dedicated video, only embedded video on s

thats way too low for gpu memory line...could be that only one memory modul is broken but probably a few of them and gpu..but you can not be 100 % sure before removing them (desoldering). You can try with lab power supply (0,8 vol) and see what gets hot with thermal camera (if you have one)...but i have seen several times where one of the memory chips is getting hot..then you remove it then second one gets hot...and finally you remove them all and find out that memory line in gpu is also shorted (gpu dead).