Yes indeed, that's what I have in mind as well.
hgg
Member
Last Activity: 10-26-2017, 09:44 AM
Joined: 10-25-2014
Location: Athens
-
Re: Core i7 short to ground, possible cause?
Yes indeed, that's what I have in mind as well.
-
Re: Core i7 short to ground, possible cause?
I have this one but its nothing near what you should have for the job...
[url]https://www.amazon.com/Opti-Tekscope-Digital-Microscope-Definition-1600x1200/dp/B00PEZ3GMK[/url]Re: Core i7 short to ground, possibl...0PEZ3GMK[/url]Leave a comment:
-
Re: Core i7 short to ground, possible cause?
Hmm, yes, that's what I want to avoid because its a 25 pin BGA 2x2mm in size..
I guess I have no other choice though.Leave a comment:
-
Re: Core i7 short to ground, possible cause?
The output of VT357 has been completely disconnected because I removed L30.Leave a comment:
-
Re: Core i7 short to ground, possible cause?
Which 3rd component? There are a lot on this line!
There is the DC-DC converter VT357 and it has its input shorted with its output.
Is it possible that this is what is creating the problem?Leave a comment:
-
Re: Core i7 short to ground, possible cause?
That's what I mean.
This line is shorted to ground and either the CPU or the VT357 is creating the short.Leave a comment:
-
Re: Core i7 short to ground, possible cause?
I have tested the capacitors on the lower left and they are all sorted to ground.Leave a comment:
-
Re: Core i7 short to ground, possible cause?
Ok, with L30 removed, I applied 0.7V/1.5A to pin 2 of L30 and I got the same
thermal signature. Lower right side of the CPU in the photo getting hot again.
Although the DC-DC chip shorts its input with its output please have a look at
the following component schematic:
[url=https://postimg.org/image/6b0rgzsb7/][/url]
All the blue pins are interconnected with the remaining shorted rail.
The marked capacitors on the lower left are all shorted to ground as well.
...Leave a comment:
-
Re: Core i7 short to ground, possible cause?
The 1.5V rail inductor L30 has been removed and the 5V rail cleared
of any shorts. MOSFETs and capacitors are all ok now!
If you have a look at the diagram some posts above, pin 1 of R819 (VDD) and
pin 1 of inductor L30 (VXD) of the DC-DC VT357FCX chip still have a short.
Does this mean that the IC is definitely fried ?
The other thing is that on the VT357FCX pin VCC_SENSE_VTT is also
shorted to ground and a series of capacitors along the CPU VCC1R05
rail...Leave a comment:
-
Re: Core i7 short to ground, possible cause?
Great, I think this is what I will try.
I will let you know.
Thank you very much for your help!Leave a comment:
-
Re: Core i7 short to ground, possible cause?
So, maybe its more convenient to start removing inductors and see which part of
the circuit remains shorted in order to close on the faulty component.
What do you think?Leave a comment:
-
Re: Core i7 short to ground, possible cause?
The CPU is soldered to the board, so replacing it its out of the question because
I do not have anything close to a BGA rig.
When you apply current to the shorted rail isn't logical to assume that only the
shorted components will get hot? The only thing that gets hot is one side of
the CPU die.Leave a comment:
-
Re: Core i7 short to ground, possible cause?
Just checked and there is a direct short (0.35 Ohms) between VDD (input) & VXD (output)
of the VT357FCX chip.Leave a comment:
-
Re: Core i7 short to ground, possible cause?
I have already found the components that have a short because
thats where I started from. Two MOSFETs on the 5V rail present
a short, but that does not mean they are actually shorted. Anything
on the 5V rail could be the cause. For example all the capacitors
on the same rail present a short. That is why I used high current to
find out what was getting hot.
The thing is that if its the VT357FCX that shorts the rails, then why
it does not get any hot ???
You can find...Leave a comment:
-
Re: Core i7 short to ground, possible cause?
@khaahk Its a Lenovo laptop and I have the schematics.
Yes 3V was not necessary. It was a 5V rail though.
@caspian I measured all the inductors for shorts to ground:
L26 (5V) : 0.8 Ohms
L27 (3V) : M Ohms
L24 (Charger Out) : 20 KOhms
L25 (5V) : 0.8 Ohms
L34 (VCCSA) : 22 Ohms
L31 (VCC1R05AMT) : 78 Ohms
L29 (VCCGFXCORE) : 6.8 Ohms
L30 (VCC1R05_VTT) : 0.8 Ohms
L32 (VCC1R5A_VX) : MOhms
5V rail is shorted for sure.
Now L30 looks like a short as...Last edited by hgg; 10-26-2017, 01:28 AM.Leave a comment:
-
Re: Core i7 short to ground, possible cause?
On the CPU you mean?...Leave a comment:
-
Core i7 short to ground, possible cause?
Hi guys,
I am trying to troubleshoot a used laptop motherboard I bought which refuses
to power on. Before the problem, I've installed a mSATA SSD and installed
Windows without any problems. At the end I powered off the laptop and I
wanted to install an antivirus as well. After the shutdown it never powered on
again.
I removed the motherboard and what I found was a short to ground on the
5V rail. After a lot of searching I could not find the faulty component and
I injected 3V @ 3A in the 5V rail in order to see what... -
Re: Dell Ultrasharp 2408wfp Shadows
Thanks! I might try it.Leave a comment:
-
Re: Dell Ultrasharp 2408wfp Shadows
I see. I thought that is appeared by itself.
There are other owners though that have similar problems with the 2408wfp.
Did you clean them with ordinary rubbing alcohol?Leave a comment:
-
Re: Dell Ultrasharp 2408wfp Shadows
Risky business... but when I find the time I will try it.
It looks like that the wfp series develops the same problem after prolonged use.
Thanks.Leave a comment:
No activity results to display
Leave a comment: