820-3332 suddenly shuts off with kernel panic


New member
Hi guys, I have this 820-3332 that shuts off when I try to install a new OS (I'm doing it in an external ssd with usb adapter because internal doesn't work, I don't know if this is because ssd is faulty or because the board) I can boot from usb, and I can say "install" choosing the ssd, but when it starts to install with black screen and white apple logo, it shuts off.

I ran EFI ASD and one sensor readings is much higher than it should do. It says:

Location : IHSC
Type: Current
low-limit: 0.0 A
high-limit: 0.05A
description: Debug TBT T29 current
reading 0.825 (more or less, sometimes 0.832, sometimes 0,822...)
noise-tolerance: 1.0

So I supposed this sensor is the cause of kernel panics, but I can't find why it gives me that value. I have looked for any broken trace or something strange near UD250 but can't find anything.. What should I look? Thank you!


New member
Remove Q3880 and try again.
Do not forget to reflow/resolder/change U8900, just in case.
I'll try it, but, will this disable thunderbolt I guess. Am I right? I'm still learning, and I have so much to learn,.. I already reflowed u8900. If I remove q3880, what should happen?
I'll do it ASAP


New member
Where is gmux? Schematics say u9600 but I can't find it on brd. I already removed Q3880 and EFI hardware profile reads the same. 0,819A on that sensor. Something that I forgot to say is the board starts always, but when I shutdown it, it won't turn on again at the moment, I have to wait a few minutes.. but if I disconnect battery it seems to turn on faster. It's very strange..
Last edited:


Staff member
Ooops, I just saw ISHC sensor on the schematic.
Change all RD251-254.
You can also change UD250.
Be sure to have good continuity to RD259; does it have correct value (10 miliohms)?
Short (for test) CD250 and see if machine still turns off.


New member
I have shorted cd250 but it continues turning off after logo appears... I will replace all components and try again. Reading now is 0.00 of course.