ASUS ROG GA502D missing 19v

[jeweemiah]

Re: ASUS ROG GA502D missing 19v

I already did all of that when I was replacing the IC again for the 3rd time. Still no luck

[mon2]

Re: ASUS ROG GA502D missing 19v

1) Post pics of the area being reworked.

2) Remove all power. Meter in resistance mode. Check the resistance to ground for each pin of the first 2 mosfets.

3) the charger IC will shut down if there is a short or if it is unable to measure the current flowing through the legs of the circuits. The current is measure by voltage drops across the current sense resistors. If for some reason, the voltage drop is too much then the charger will shut down the mosfets.

Aside from the charger IC, other surrounding parts need to be also reviewed - see the datasheet from TI that offers a reference schematic that should be very close to the one used by Asus.

[GRACIOUS COMPUTERS]

Re: ASUS ROG GA502D missing 19v

Good day. I have similar problems and I need help.
Please a client brought his Asus gaming laptop for repairs which he angrily, as he claimed went for it from the person working on it because he said the CPU was shorted to GROUND because it was getting hot.

In fact when I received the laptop and open it, some component where removed and not replaced. So I replaced the component. Upon checking I with a schematics diagrams and board view I bought it was shorted to GROUND at the second mosfet. Upon removing the mosfet still shorted. I injected 3.0vts and 0.50amps and it was shorted to GROUND with 1.5vets.

[mon2]

Re: ASUS ROG GA502D missing 19v

Hi. Can you post the schematic and boardview files for the review?

[GRACIOUS COMPUTERS]

Re: ASUS ROG GA502D missing 19v

Please this is the attached file

[GRACIOUS COMPUTERS]

Re: ASUS ROG GA502D missing 19v

So this are images from the shorted board.
The second mosfet shorted. And the cpu getting hot.

[mon2]

Re: ASUS ROG GA502D missing 19v

Thank you for the posting of the logic board files.

Never inject a 'high voltage' onto any rail, just in case a mosfet could be shorted downstream and then cause damage to the CPU.

In general, keep the injection voltage < 1 volt till more details are confirmed and is safe to do so.

If the CPU is getting hot, the CPU may already be dead.

Remove all power / no battery -> meter in resistance mode (lowest scale).

Check the resistance to ground of the CPU rail. What is the resistance ?

[GRACIOUS COMPUTERS]

Re: ASUS ROG GA502D missing 19v

In resistance mode for the rails is 5.9 - 9.9 ohms.
Below are some pictures of the board and unstable meter reading.

[mon2]

Re: ASUS ROG GA502D missing 19v

Such resistance values may be ok for the CPU.

The hot to touch of the cpu surface is very normal since you do not have a heatsink on the component. Apply heatsink compound or pads and the proper heatsink to keep the cpu cool.

Do not run the logic board without a heatsink else the cpu can burn out.

Next, without power / no battery, check the resistance of the dc in mosfets to confirm they are not shorted.

Have you already replaced the 2nd mosfet that you found to be shorted?

Is the main 19v logic board rail showing as a short?

Again without power, what is the resistance to ground for the 19v rail that powers the logic board?

Also, place antistatic bags or cardboard under the logic board to prevent static charge to the logic board or parts. Mosfets can get damaged from ESD events caused by static charges.

[GRACIOUS COMPUTERS]

Re: ASUS ROG GA502D missing 19v

Sorry for replying now.
I have checked from the D.C.port soldering everything looks okay to only the 1still mosfet and in the input of the second mosfet which is shorted. I replaced it with similar one still shorted to the ground. I am confused and don't what to even check again. The problem for me now is to how to get of shorted to GROUND on the second mosfet output. I believe once I solve that the laptop will be okay with the cpu since you think the cpu reading is okay. So please help me with this shorted output of the second mosfet line.

[mon2]

Re: ASUS ROG GA502D missing 19v

Again without power, what is the resistance to ground for the 19v rail that powers the logic board?

This is the side AFTER this 2nd mosfet. You may have a shorted cap on the main power rail.

Do you have a lab power supply that is adjustable?

[GRACIOUS COMPUTERS]

Re: ASUS ROG GA502D missing 19v

I am home now without the board. I must check and update your. Concerning the power supply I have.

[GRACIOUS COMPUTERS]

Re: ASUS ROG GA502D missing 19v

Please I have checked and want to update you on it . Above is the attached pictures of the resistance record on the main power line without power.

[Sephir0th]

Re: ASUS ROG GA502D missing 19v

The CPU surely died already a few times. Classic case of main power rail shorted with CPU_Core or secondary CPU-supply, no?
Proof by checking resistance between main power rail and one of the coils near the CPU. Why does your MM still show KiloOhms instead of Ohms in your last pic?

[GRACIOUS COMPUTERS]

Re: ASUS ROG GA502D missing 19v

Okay so this is update to your question please. The reading of the meter on the 19vt power lines to the input of the second mosfet is still the same please.

[GRACIOUS COMPUTERS]

Re: ASUS ROG GA502D missing 19v

The above pictures shown is about the cpu rails and and the shorted mosfet.

[GRACIOUS COMPUTERS]

Re: ASUS ROG GA502D missing 19v

Try injecting 1vt and starting at amps of 0.50 - 4.45 but the the mb was still doing 0.21amp. Checked with the meter while the power supply is connected to the Mb and the shorted component where doing 1.0vt except the CPU rails doing 0.00.

[mon2]

Re: ASUS ROG GA502D missing 19v

Hi. The cpu resistance to ground at ~5 ohms is not considered a short.

Yesterday we almost assumed that for a macbook a1398 (820-3332), with a cpu resistance of 1 ohm to ground was a dead cpu. The board was no longer booting. After contacting another tech from this forum he suggested to test with a battery connected. Then the board booted right up!!

Do not inject more than 1 volt unless instructed otherwise as a shorted high side mosfet can pass the high voltage onto the vcore rail of the CPU and then it is game over.

The cpu without a heatsink will of course be hot to the touch. I know I almost burnt my knuckles one time before fresh heatsink compound and heatsink was applied.

So perhaps the CPU is still ok.

Go back to your basics, start with the dcin adapter.

What are the voltages on each pin of the DCin mosfets?

With care, what are the voltage measurements of each pin of the charger IC?

Post the measurements.

[loveliss]

Re: ASUS ROG GA502D missing 19v

Greetings!
Seems I share a similar fate as these fellows. I have an Asus GA502D as well. Does not power on and no lights. Just so you know. I know nothing (I mean nothing) about how to really test for anything really. I watched a video or two. What I found with my laptop is at the first mosfet (upper in pic) I have 19v at the Darin (top pins?) and nothing on the other side (gate and source?) On the second mosfet I don't get any voltage on either side. Nothing seemed shorted testing the mosfets themselves... but when I check the drain on the second mosfet it was shorting to GND (black probe on shielding of pwr connector, red on drain pins). 19v doesn't seem to get past the drain on the first mosfet. Also. With the power cord plugged in. The cpu/gpu DON'T seem to get hot at all. Touching around the board (I lack a thermo cam) Nothing seems to get hot that I've notice so far. And the whole board looks flawless, nothing crispy.
Remember I'm an uber noob at this.. I just have really good soldering skills from past work. What do you gentlemen think?