Macbook 2009 820-2610-A, power cutting off

[estelanim416]

Hi

Strange one.
Works perfectly when booting to recovery or usb stick, but cots the power on normal boot, the moment a first bit of the progress bar gets filled.
Did smc, vram reset, new os instalation - it seems to work then. But after cooling off (next day ie) it happens again.
Checked the notorious C7771 but looks like its not it on this occasion.

Anything else that could cause that?

 

[2informaticos]

Bad C7771 will not allow the board to start at all.
There is no ME region, so shouldn't be BIOS issue.
If always work good on USB OSX, try other HDD drive and flex.

 

[estelanim416]

Yes, installed os on a new ssd, have not tried a new sata cable but I cant see that this would do it

Once it gets going it will work forever, shutting down, restarting etc all works. Only when i leave it off for a couple of hours it goes back to this cutting off
I can boot into recovery with no issue thou, recovery partition being on the same disk

Happy to replace the hdd cable but I strongly feel this is not the culprit

 

[estelanim416]

New sata cable in but unfortunately, same thing happens.
Dont know which direction to go here really?
Constantly pressing on the keyboard somehow makes it boot, I am guessing I am draining something by pressing??? Its a real mystery for me

BTW, I can boot via usb from the same disk, so I am guessing something to do with the SATA power???

 

[2informaticos]

Try to start with internal SSD on SMC bypass mode.

 

[estelanim416]

Yes it does work!
It works after shutting down as well.
What do you think is wrong?

 

[estelanim416]

After an hour off, it does the same again :/

 

[2informaticos]

If on SMC bypass works good, then should be some SMC current sensor, I suppose.
Run ASD, see if any error pops up.
Set On Error to Continue, before start the test.

 

[SMMRepair]

Reflow GMUX.

 

[estelanim416]

ASD passes :/ run it a few times. Reflowing GMUX sounds random - any reasoning behind it?

 

[2informaticos]

Use software like gfxcardstatus and switch graphics between U1400 and U8000.
See when the machine fails.
ASD EFI runs under U1400 graphics, seems that your problem is U8000.
You can do more tests with ASD OS version, which can access and test U8000.

You can also connect external monitor.
This will force dedicated graphics (U8000) and stress it with Unigine, or other software.

 

[estelanim416]

I did both ASD, there is no gpu issue as far as I can tell. It feels like there is some "static" that needs "draining" before it can start.
If I remove ram and pop it back in, it starts working, I will plug external disk, it works, keep bashing keys on the keyboard, it works.
After that, it works until I leave it off for a couple of hours, then it starts cutting off again :/

I will run Unigine to double check

BTW: the power cut off happens only during boot, when the progress bar appears and the moment you see the first millimetre filled, boom. Once we get through that, it works perfectly

 

[estelanim416]

OK, Unengine runs ok but shows 129 C temp - could that be anything?

 

[estelanim416]

Installed HWMonitor, GPU Die 129C, GPU 2 Heatsink 2 129 C.
Not sure if this one doesnt have sensors or is something really wrong

 

[2informaticos]

129 degrees on GPU die is normal when runs on U1400 graphics; GPU temp is not monitored in fact.
When U8000 graphics is used, GPU die should monitor the real temp of U8000.

Try known good working BIOS, just in case.