Asus N53SV Dead No Power

[grahamw01]

Re: Asus N53SV Dead No Power

Hi again, I have now replaced the 1 shorted CPU mosfet and there is slight progress.

As soon as I plug the AC in the power, wifi, caps/num/touchpad lock, and power leds light up straight away. After a while the fan starts to spin, other than that there is no sign of life. I can turn the machine off by the power button but when I turn it on again it cycles turning on and off every few seconds.

If I plug it in and leave it on for a while, the GPU coils get the warmest but only a little bit warm, the GPU itself warms up just a little less than the coils, the small chip (near the CPU touching the heatsink) warms up about as much as the GPU, I can't tell if the CPU heats up, I think it just feels hot because of the heat from the other chip travelling through the copper, I don't think the CPU is producing heat though, the CPU coils don't feel hot at all nor do any of the mosfets. so??

thanks

[grahamw01]

Re: Asus N53SV Dead No Power

I just had a quick check of voltages, the GPU and CPU have a few capacitors with about 1V on them, there is 2 mosfets with 19V on the drain near the CPU, the GPU coils have about 1V on them, the CPU coils have 150mV and about 50mV.

[khaahk]

Re: Asus N53SV Dead No Power

CPU coils should have 0.8-1V, there might be 2 coils for cpu and 1 for cpu-s gpu. The nvidia gpu ~1V is ok. The other chip - you mean intel pch ? - it should not get hot.

[grahamw01]

Re: Asus N53SV Dead No Power

yes I meant the intel pch, its not very hot just enough to know there is power going to it.

what do the 6 mosfets near the power input do? I think they are working okay but not sure if the gates are correct.

The first 2 have 19V in, 1.18V on gate and 1V on source. the next 4 have the 1V on drain but 4.7V on gate so nothing on source.

The 6 near the CPU, the 3 feeders (I dont know what to call them) have 19V on drain, but none of them have a gate voltage

[khaahk]

Re: Asus N53SV Dead No Power

6 mosfets are part of GPU VCORE, as you have 1V on GPU, these should be ok. You should concentrate on CPU, do have a spare one to try? If one of the mosfets in cpu power circuit failed, then the cpu might be dead...

[grahamw01]

Re: Asus N53SV Dead No Power

I don't have a spare CPU to try but if we assume CPU is okay, then what? I guess there is no power going to CPU since none of the mosfets have a gate voltage.

If the motherboard was working fine and I remove the CPU should it make beeping noises or something?

thank you

[grahamw01]

Re: Asus N53SV Dead No Power

I removed the CPU, it doesn't make any beeps, but the fan spins strangely. it pulses on and off every second. Also the CPU coils all have just over 1V when the CPU is removed.. does this mean 100% the CPU is damaged? I really hope not, it would be expensive just to check as I need to buy another CPU..

[khaahk]

Re: Asus N53SV Dead No Power

100% is when you change the cpu and the new one works.
What is the resistance on cpu coils? Do you remember the position of the damaged mosfet?
If it was the upper leg of the buck controller then it is most likely that processor has died.

[grahamw01]

Re: Asus N53SV Dead No Power

The image attached shows the one that was shorted

thanks

[grahamw01]

Re: Asus N53SV Dead No Power

resistance on all coils is 0 ohms

[grahamw01]

Re: Asus N53SV Dead No Power

I am pretty sure the answer to this is no, but I do have an i7-720qm processor. The current CPU is an i7-2720qm, both of them are for an rPGA989 socket, so are they compatible? Could I put this 1st gen i7 in the N53SV?

thanks

[khaahk]

Re: Asus N53SV Dead No Power

The mosfet is high side, so if it shorted S-D then adapter voltage was applied to cpu. If you remove the cpu, then the resistance goes high?
The 720qm is not in supported list of hm77.

[grahamw01]

Re: Asus N53SV Dead No Power

this is hm77? how do I confirm that? apparently the current CPU, i7-2720qm is not supported then, its only 3rd gen i7's

[grahamw01]

Re: Asus N53SV Dead No Power

oops I was just measuring resistance across coils not to ground, im reading 18.7 ohms and 11.8 ohms when the cpu is in, reading fluctuating MOhms ~ kOhms with no CPU

[khaahk]

Re: Asus N53SV Dead No Power

Sorry, it is an HM65 chipset, i have Intel 2760QM - it is showing resistances of 7.4 Ohms (CPU Core) and 13.3 (GpuCore of CPU). It is hard to say what is wrong. When dealing with impulses it is hard to do any conclusions only measuring voltages. For that you need an oscilloscope.
I have attached a picture of high side CPU mosfet gate voltage of the same mainboard which is having impulses of 25V, but they are present not so often so that digital MM is showing only 1.3V. Low side gate of CPU mosfet shows 4.5V with multimeter, but having 5V impulses which happen more frequently.
CPU is powered with ISL95831, pin 7 is enable signal, is it high?

[grahamw01]

Re: Asus N53SV Dead No Power

Hi, thank you for the information, pin 7 is 3.373V with or without the CPU. CPU coils are 1V with no CPU, and a few mV with CPU. Hope this helps!

[khaahk]

Re: Asus N53SV Dead No Power

Take good quality macro shot from cpu surroundings both side of the board. If somebody has poked around the board before you, anything could be wrong...

[grahamw01]

Re: Asus N53SV Dead No Power

I have attached a few images. Also regarding the heat of the intel pch, voltage on the big coil near it is 1.5V although I have no idea if this is related

Regards

[khaahk]

Re: Asus N53SV Dead No Power

Nothing out of ordinary can be seen on these pictures, the 1.5V is ok on that coil. Next thing to do is to try another cpu...
Without cpu the mainboard acts as described, vent is on/off and all coils show 1.1V.

[grahamw01]

Re: Asus N53SV Dead No Power

Okay, that is good news that your motherboard does the same with no CPU, I am just waiting for the CPU to arrive now. Thanks again!