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cpharlok
12-26-2017, 07:32 PM
Hi,

Since several weeks ago I have a problem with my Asus G751. After returning from Tech service as the LED panel failed (Asus changed it at no cost as warranty), another problem appeared. When I try to load intensive GPU/CPU tasks like gaming, with the charger plugged to AC, the battery mode icon appear on screen, and act as if I just unplugged the charger/adaptor from AC. If I keep the computer low on resourcers (like surfing the internet, using Word, watching a movie...) that does not happen, and battery is at 99%.

Seems that when the power demand goes up, the charger can't deliver the amps needed. Then, I need to power off the computer for several minutes to make the charger work again.

Should I buy another charger? (I think it is a 230W one) or may be something related to a component inside the laptop? I do not have money to buy an expensive 230W charger just to see the same thing happens. Unfortunately, warranty has just expired :(

Thank you!

Harlock

xeromist
12-27-2017, 01:48 AM
I concur that sounds like a charger problem. Unfortunately you are correct that the best way to test it is to try another one. You might see if you can find a seller that has a return policy so you can send it back if something else is wrong.

cpharlok
12-27-2017, 01:25 PM
Yes, seems it's the best option. Thank you

JustinThyme
12-27-2017, 04:21 PM
I doint know about switching to battery but some do draw from the battery under heavy loads.
Which G751 are we talking about? If its the JY then this behavior is perfectly normal as the brick cant keep up with the power demand of the CPU and GPU.

xeromist
12-27-2017, 06:16 PM
I doint know about switching to battery but some do draw from the battery under heavy loads.
Which G751 are we talking about? If its the JY then this behavior is perfectly normal as the brick cant keep up with the power demand of the CPU and GPU.

But does it actually display the battery icon when that happens?

cpharlok
12-27-2017, 11:08 PM
I doint know about switching to battery but some do draw from the battery under heavy loads.
Which G751 are we talking about? If its the JY then this behavior is perfectly normal as the brick cant keep up with the power demand of the CPU and GPU.

It is the JY, yes, with a 980GTX and 3 hard disks (1 ssd, 2 spin) so it is power hungry. The problem is the battery icon appear, orange led turn off, and begin to draw power from the battery until it is depleted. If I leave the game and return to windows (or stop a render of After Effects for example), brick does not begin to charge again, that is, orange charging led does not light. It is like the brick is dead. Also, if I touch the numeric keyboard, specially at 0 key, is very very hot. That behaviour did not show before sending the laptop to Asus for screen repair (it may be just a coincidence).

If the problem is the power brick, where can I find a reliable seller with high quality power adapters? Seems the one that came from ASUS is not up to the task (and I really do not game or render a lot, just once in a month really).

What really worries me is the power plug (it is very hot when the switch to battery happens) and the numeric keyboard hot point. It may show that is not really the power brick, and something inside is not working ok. The problem is I have to order to china or EEUU, I did not find any seller of a 230W in Europe.

xeromist
12-27-2017, 11:44 PM
So the same power brick did not have the same problem before the screen replacement and presumably it stayed in your possession? That along with the hot spot do cast some doubt on the issue as purely a problem with the brick. However I'm not sure there's a better way to confirm that.

cpharlok
12-28-2017, 12:05 AM
So the same power brick did not have the same problem before the screen replacement and presumably it stayed in your possession? That along with the hot spot do cast some doubt on the issue as purely a problem with the brick. However I'm not sure there's a better way to confirm that.

I sent the power brick to asus alongside the laptop... never thought it could be another brick really. For now, I am avoiding 3D gaming (only play emus and FTL:Faster Than Light) and do basic things like browsing and office things. Strangely, RAR compression at ultra level does not trigger the effect (and it gets CPU to 100%).

The first time it happened I was playing Planetside 2, some days after I received the laptop.

xeromist
12-28-2017, 05:25 PM
That's not surprising. The GPU would increase power usage significantly. And yeah it could be another brick. They aren't distinctive so it could have been mixed up.

cpharlok
12-28-2017, 07:15 PM
Well, I suppose I have no choice but to order another brick then, it's the best option I have now.

cpharlok
02-01-2018, 02:13 AM
Well, things look bad. Ordered a new brick, and does the same thing. Seems the problem is on the main board, and warranty ended about 3 months ago. Now my 980M is unusuable, it's just a regular 17" laptop. Any intensive graphics app or game reverts to battery, and it is not a brick problem. I need to power off the laptop and wait two or three minutes to recover charging/AC power.

Darnassus
02-01-2018, 06:36 AM
Okay so...

When you're plugged in, and it's charging.. you start to play a heavy loading game.

Your Battery begins to go down... correct? If so.

HOW MUCH..? What percentage is it dropping to?

Is it completely dying as if it ran out of battery?

If I understood correctly, you also said that once you play your game, your charger STOPS charging the laptop. So it's left running on only the battery. Correct?

More details about battery behaviour please. It is natural for these notebooks to share load from the brick and the internal battery down to roughly 90%.

cpharlok
02-01-2018, 09:20 AM
Okay so...

When you're plugged in, and it's charging.. you start to play a heavy loading game.

Your Battery begins to go down... correct? If so.

HOW MUCH..? What percentage is it dropping to?

Is it completely dying as if it ran out of battery?

If I understood correctly, you also said that once you play your game, your charger STOPS charging the laptop. So it's left running on only the battery. Correct?

More details about battery behaviour please. It is natural for these notebooks to share load from the brick and the internal battery down to roughly 90%.

It behaves as if you unplug the brick, the battery goes down normally, but AC is not more. That's why I thought it was the brick, that got overloaded and shuts down. Battery LED is off. If I leave the game and return to desktop, charging does NOT return, I have to power off system completely and wait 1-2 minutes with brick unplugged. Then I plug it again and battery LED goes orange, charging.

Seems now almost clear to me that is a problem in the power internal circuit: something is broken and can't cope with an amperage above X

After some tests:

- Heavy CPU load: No problem
- Faster Than Light (simple 2D game): No problem
- Age of Wonders 3 (simple strategy game with 3D): Short Battery switchs, charging still holds, battery LED green, the battery icon appears but AC charging returns almost a second after.
- Skyrim (Low settings): Does lasts for about 10-40 seconds. Then goes to battery, charging no more until I power off system. Battery drains as usual, fast but I think it is normal as the game is power hungry (maybe can last about 30 minutes)

Darnassus
02-01-2018, 09:37 AM
Can you use a GPU + CPU intensive bench for roughly 30 mins and monitor it?

Could be something separating from heat..

cpharlok
02-01-2018, 09:41 AM
Yes, I will do a 3D Mark or something like that and check the temperature. I will post the results when ready.

cpharlok
02-01-2018, 10:46 AM
UPDATE: If I wait 2-3 minutes after the switch to battery, then I just unplug and plug the AC connector, the charging returns. No need to power off system.

Seems it is not related to temperature, with a cold system, the behaviour happens, so it is more related to 980M power load.

ufotheswe
02-03-2018, 01:22 AM
Hey I am having the same issue, but its also switching to battery when I am browsing now. I tried a new battery, I tried a new AC jack in. Nothing works.

And if I try to open a game, the laptop shuts off.

:( This is horrible

Do you know if there is a way to undervolt the 980m? Did you already try it?

cpharlok
02-03-2018, 09:55 AM
Hey I am having the same issue, but its also switching to battery when I am browsing now. I tried a new battery, I tried a new AC jack in. Nothing works.

And if I try to open a game, the laptop shuts off.

:( This is horrible

Do you know if there is a way to undervolt the 980m? Did you already try it?

I don't think making the 980m work below its voltage will help (it that's even possible to do). What I have done is testing if the problem is related to power intake of the 980m, and seems it is. In my case, when the graphic card go up XX watts, the system revert to battery. Today I will get a power meter to check how many watts are the threshold for battery change and AC shut off. The worst thing is my laptop was working OK before sending it to ASUS (I sent it because the screen failed, no hit or something, just lost a color and did strange things) returned with screen fixed and clean, but I did not try any game immediately, so I could not realize of the problem until was late to send it again.

ufotheswe
02-03-2018, 02:47 PM
I don't think making the 980m work below its voltage will help (it that's even possible to do). What I have done is testing if the problem is related to power intake of the 980m, and seems it is. In my case, when the graphic card go up XX watts, the system revert to battery. Today I will get a power meter to check how many watts are the threshold for battery change and AC shut off. The worst thing is my laptop was working OK before sending it to ASUS (I sent it because the screen failed, no hit or something, just lost a color and did strange things) returned with screen fixed and clean, but I did not try any game immediately, so I could not realize of the problem until was late to send it again.

I understand, but my rig changes to battery even just by opening a new tab in chrome :D. But maybe its too much for the 980m

Greuh
02-07-2018, 09:19 PM
Hi, since u got no responses i was thinking your issue seemsrelated with mine and also with :
ufotheswe https://rog.asus.com/forum/showthread.php?99782-G751jy-switching-between-battery-and-AC-Shuts-off-when-stressed
SuperWeapons2770 https://rog.asus.com/forum/showthread.php?98919-Asus-G751-JT-randomly-stops-charging


I also changed the battery and it is still randomly charging. I tested the power brick with a multimeter and it seems fine.

cpharlok
02-08-2018, 08:55 AM
Hi, since u got no responses i was thinking your issue seemsrelated with mine and also with :
ufotheswe https://rog.asus.com/forum/showthread.php?99782-G751jy-switching-between-battery-and-AC-Shuts-off-when-stressed
SuperWeapons2770 https://rog.asus.com/forum/showthread.php?98919-Asus-G751-JT-randomly-stops-charging


I also changed the battery and it is still randomly charging. I tested the power brick with a multimeter and it seems fine.

Very interesting, I will test the driver downgrade solution, I hope that works. Also, the ufotheswe thread with tests is very interesting, I will try to help if I have some spare time, I am now overloaded with work. Did you try the downgrade?

Gianandrea_Franzoni
02-21-2018, 12:34 PM
Hi,
maybe i can help.
I had the same problem for months, then the laptops stop charging completely.
I replaced the dc in pcb (not only the jack) but the complete PCB.
After the replacement I never had the mentioned problem again.

cpharlok
02-21-2018, 02:16 PM
Hi,
maybe i can help.
I had the same problem for months, then the laptops stop charging completely.
I replaced the dc in pcb (not only the jack) but the complete PCB.
After the replacement I never had the mentioned problem again.

I was afraid that was the issue, makes sense. Can you please tell us how to do it? Where to order the PCB? this can be done at home?

Gianandrea_Franzoni
02-21-2018, 03:29 PM
I bought the part from asusparts.eu the parts number is 90NB06F1-R10030 the PCB i got is marked "g751jt but it is 100% identical to the one in my JY. The only difference is the mark on the board.
In order to change the PCB you need to disassemble the laptop completely but no soldering is needed.
I had mine fixed at a repair shop... And guy there said that to him the board seem too weak for 230w in fact the old one look spotless connector and everything but doesn't work.

cpharlok
02-21-2018, 03:56 PM
Thank you for the valuable information. What I do not understand is, after looking the piece with that part number, I see only a jack connector, no electronics. My jack is perfect, not physically broken. Did you remember if the piece has electronical parts or was only the connector itself? Like the image attached:

71800

Gianandrea_Franzoni
02-21-2018, 09:47 PM
There is no electrics on the board, but in my old pcb you can see some damage to the soldered spot on the back.
https://thumb.ibb.co/ganyDH/P80221_223221.jpg (https://ibb.co/ganyDH)
My guess would be that after 3 years the temperature under 230w load have literally cooked the pcb.
Before ordering the new pcb we tested the soldered points under the connector and they were fine, but ther was no current coming through 2 of the connector on the side of the pcb.

cpharlok
02-21-2018, 10:00 PM
I see. It's really strange that the bad connection limits the amount of amps that go through the DC pcb... I think I will have to have a look at mine and check