A1286 2,2ghz late 2011 fans spin on / off for 1s

[vinifera]

Hi,

There's a short circuit on PPVCORE_S0.
See attached in red, which components I have removed and I still have a short circuit on PPVCORE_S0.
So the short is in the line from R8940 (see appendix 2).
or in the GPU chip or in one of the capacitors (see appendix 3).
The question now is how can I find the capacitor that could be broken ? A separate power supply of 0.9V on PPVCORE_S0 with an adjustable current ? Is this a good idea ? and then measure the temperature of each capacitor ? Does anyone have experience with this ? What equipment do you use for this ? I can't solder every capacitor, can I?

[piernov]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

Short as in how much resistance to ground?

This is gonna have a dead GPU btw, regardless of being shorted or not. Check if it's been reflowed too.

[vinifera]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

In short i have 0 ohm
Yes i reflowed the GPU
I was part of the reflowing a sound. It seemed like a sound that a component was blown up. But visually I didn't find a broken component ?

[KvnTM]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

In short i have 0 ohm
Yes i reflowed the GPU
I was part of the reflowing a sound. It seemed like a sound that a component was blown up. But visually I didn't find a broken component ?

How did you reflow the GPU? It doesn't make any sense to reflow GPUs of 2011 MacBooks since they have a manufacturing defect. Also it sounds like you "popcorned" your GPU or delaminated your board. This happens when you apply too much heat to one area without preheating the entire board. If this happened your board is gone.

You can inject voltage into a power rail but limit your current to an amp max on vcore lines. Splash some alcohol onto the board and look where it quickly evaporates.

But since you heard a pop or crack you most likely damaged the board or cpu/gpu by delaminating the substrate or the board itself.

[vinifera]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

Is replacing the GPU a solution? And which equipment is best used for this? Does anyone have experience with this? Do you sometimes have some references of equipment and what is the best price quality for hobby?

[KvnTM]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

Is replacing the GPU a solution? And which equipment is best used for this? Does anyone have experience with this? Do you sometimes have some references of equipment and what is the best price quality for hobby?

Replacing the GPU is a waste of time and money. It will fail again.
And I ask again: How did you reflow the GPU ?

[vinifera]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

Reflow with the YIHUA 852D++ model

[KvnTM]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

Reflow with the YIHUA 852D++ model

First it is not a good idea to reflow huge bga's with a heatgun. How hot did you set it and how long did you apply heat ?

[vinifera]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

Which device did I have to use for this? Unfortunately it happened and now I'm looking for a bga rework station? Can you recommend me something?

[KvnTM]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

Which device did I have to use for this? Unfortunately it happened and now I'm looking for a bga rework station? Can you recommend me something?

Would be easier if you answer my questions. You most likely destroyed the board with excess heat since you heard a crack sound. You should have made some research before even touching the GPU on 2011 MacBooks. There is no reason at all to even think about reworking them.

The crack sound probably came either from the GPU or the Board itself which layers have "exploded" internally. Unfortunately this can't be fixed and you can throw the board away if that happened since the Board would have an internal short. If it happened on the GPU you can just remove it and disable its power circuit. There is another Thread on disabling the A1286 GPU where I answered this question maybe an hour ago.

If you are ready to spend thousands of dollars you could invest in a proper bga rework station. Preheating the board and thermal profiles are a must when doing this kind of work. Anything else will damage the board even further to a point where its not repairable at all. Which probably happened to you.

You already mentioned that gpu vcore has a 0hm short to gnd if I remember correctly. You could try to inject voltage into the power rail. If the thing draws a couple amps and the GPU gets hot you may have only a short inside the GPU. If the whole board warms up slightly or stays cold in that area while drawing a few amps you can throw it away. A shorted cap or something else would instantly heat up and burn away.

[vinifera]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

i heat it arround 250°C about more then 10 minutes

[KvnTM]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

i heat it arround 250°C about more then 10 minutes

You most likely cooked the sh*t out of that board. Those cheap heatguns aren't accurate on temperature. I use the same for small smd parts which is fine but it is impossible to solder big BGAs with that thing.

You have 2 options:
Option A:
Toss the board and get a 'new' one. They are very cheap since all have damaged gpu's. Do not do anything with the gpu. Just disable it. You can't fix the GPU. All of them are dead. No exception.

Option B:
Remove the gpu and hope that you didn't damage the board internally.

[vinifera]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

i would go for option B, but is the bga rework station IR6500 good herefore ?

[KvnTM]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

i would go for option B, but is the bga rework station IR6500 good herefore ?

You should test the board first before doing anything else. Just ripping chips off the board won't help.
Because you have no idea if you damaged the board on your previous attempt.
Buying a BGA Rework Station just to fix a 2011 Macbook isn't worth it.
You can buy a complete MacBook for 100$.

TLDR:
Inject the expected gpu voltage and look what gets hot.
If the gpu die gets hot immediately you know its bad and then you can proceed to remove it.

[vinifera]

Re: A1286 2,2ghz late 2011 fans spin on / off for 1s

ok thanks