Asus ux510u Just trying to make sure,that my decisions seem right or not!

[Hobb7t]

Greetings fellow forumers.

The reason i'm writing this post, is to find some people who have more experience than me on electronics repair. The last month i've been dealing with an Asus laptop (ux510u) that didn't let the charger's voltage pass through the first two MOSFETs. I manage for find some burned/shorted components and replace the parts (most probably the ones that got damaged by the short), but the last one seemed like a stone that im not feeling 100% confident that is creating the issue at all. I found a whole array of caps next to the CPU which seem shorted to ground together with another batch on the back of the board. I tried to remove the front caps and the short is still there. Tried to inject voltage but as you may wonder, the CPU is the only part that gets warm. Now, my thoughts are that if i re-ball the CPU bga i may fix the whole issue, but before even i try to remove the chip, i said, hell, let's get the chance to ask for some help, you never know. I'm based in Greece so if in any case someone from the same country would like to spare some time, i could even make a phone call to give more details, but i'm not greedy, if someone else would like to wrote a line just to share his/her 2 cents i would be grateful.

[Hobb7t]

Re: Just trying to make sure, that my decisions seem right or not!

Well, 3 days passed and nobody said anything already. I do my best to get in touch with anyone who may share a thing or two, since i don't want to give up on this one. Any help will be highly appreciated

[Sephir0th]

Re: Asus ux510u Just trying to make sure,that my decisions seem right or not!

Well, before we start wasting time on this one: How much voltage and current were injected into the CPU?

[Hobb7t]

Re: Asus ux510u Just trying to make sure,that my decisions seem right or not!

Well, before we start wasting time on this one: How much voltage and current were injected into the CPU?

1.2v and around 0.7 amps which made me believe that there's still something else and it's not the CPU what causes the short

[Sephir0th]

Re: Asus ux510u Just trying to make sure,that my decisions seem right or not!

⁹The 1.2V wasn't a good idea. You have left the safe area for injecting. For this reason nobody can tell anymore whether the CPU is already dead or still fine.

It might be very important for the diagnose to know which parts were replaced and especially whether the replacement were suitable (make and model).

"Shorted" Caps around the CPU and GPU are normal and nothing to worry about. As long as you don't share exact(!) values, nobody can tell anything about that.

Then there is nothing to "wonder" that the CPU heats up when you inject there. It is normal, but it also depends on where you injected exactly(!). Otherwise, nobody can tell (again).

Reballing a BGA is rarely the solution and of course only advised when the device suffer from a drop or cold solder joint for example. You just can't fix a shorted BGA by reballing, so I don't know from there this "idea" comes.

So in summary, we still know way to less to assume anything. Way to much question marks present, especially because of the unsafe injecting and the missing basics.

[Hobb7t]

Re: Asus ux510u Just trying to make sure,that my decisions seem right or not!

⁹The 1.2V wasn't a good idea. You have left the safe area for injecting. For this reason nobody can tell anymore whether the CPU is already dead or still fine.

It might be very important for the diagnose to know which parts were replaced and especially whether the replacement were suitable (make and model).

"Shorted" Caps around the CPU and GPU are normal and nothing to worry about. As long as you don't share exact(!) values, nobody can tell anything about that.

Then there is nothing to "wonder" that the CPU heats up when you inject there. It is normal, but it also depends on where you injected exactly(!). Otherwise, nobody can tell (again).

Reballing a BGA is rarely the solution and of course only advised when the device suffer from a drop or cold solder joint for example. You just can't fix a shorted BGA by reballing, so I don't know from there this "idea" comes.

So in summary, we still know way to less to assume anything. Way to much question marks present, especially because of the unsafe injecting and the missing basics.

Thanks for the time and effort you took to write this. I will do my best to describe everything i did so far.

First of all, the issue on this laptop was it didn't let the DC supply pass the voltage through the first two MOSFETS, i could read something like 0.3v on gate, and i consider this to be normal. I did not injected voltage straight to the CPU, but on the caps next to the CPU, trying to find out if anything get's warm. I've also desoldered every cap and check for shorts (the short was still there) and put everything back again.

So far, i've changed a M3056M MOSFET, a 6.3 220uf cap on the +5v line, a USB POWER SW. BD82046FVJ-GE2, and this week will probably have a N-MOSFET PEA16BA on my hands to replace(since i found one to be shorted between source and gate).

Bellow i'm posting a board view image of the caps next of the CPU that seemed shorted.



There's an array of caps on the other side too, which are connected on the +VCCGT line too and showing a short to ground. I assumed that there's no reason for any cap to be shorted to ground, so i thought i need to fix everything before i will try to assembly the laptop and connect the bat/dc plug.

[Sephir0th]

Re: Asus ux510u Just trying to make sure,that my decisions seem right or not!

As before, without exact measurements no point to assume a short to GND. Example: a Intel i7 7th gen runs absolutely fine with 2 Ohms resistance to GND. So again, it is absolutely necessary that you share these informations.

Then you told, you injected into the caps near the CPU but not into the CPU directly. Well, you need to realize, it is no difference at all, as long as these all are connected to the same load. Btw, you still didn't shared where you injected Exactly. Most of the time the CPU circuit consists of at least Three main rails, +VCC_SA, +VCC_CORE and +VCC_GT. And there are even more secondary power rails. The knowledge where exactly you was previously playing around is a necessary Information for Further troubleshooting.

Then it seems you had issues with the +5VALW. Please clarify your findings there. It might be the case we have ro move to all of this again.

It is also not clear what mosfet (which circuit) and why you want to replace it, next.

If your answers remains like before, then we can't make any progress with your case. I try to attack you as less as possible, but it almost looks like there is no system in your troubleshooting. The issue of the wasted time can be even neglected here, since it was only your time till this point, but this has to come to an end now. And it is also dangerous for the motherboard. One serious mistake and it immediately ends up as no-fix.

So, after all this, what is the actual issue of the board, so we can start with proper troubleshooting.

[mcplslg123]

Re: Asus ux510u Just trying to make sure,that my decisions seem right or not!

Every device or a problem cant be solved by hobbyists/amateur's-some problem needs professional technicians to resolve. A simple case of main rail not crossing the first dc-in mosfet was made so complicated. Not to offend you, i'll still strongly suggest you to take it to some preofessional to give the device a chance to survive. Your understanding of laptop design is utterly wrong with your observations so far.