820-00850 Liquid damaged u7000 area. 5V 0amp USB

[kevinklinkmuller]

This thing is completely trolling me. One minute a port will show 20V, the next it will show 5V, the port next to it will start the emp meter and restart the amp meter. One minute PPbus is at 3.2 the next it's at 12.2V. The ports seem to be playing musical chairs now because it's swapping which ports is displaying 20V. Very strange

 

[kevinklinkmuller]

Now the port that was restarting the amp meter shows 20V... but it was stuck at 5V before....

 

[kevinklinkmuller]

the other thing I find strange is that the amp meter will instantly show 20V, but on working macbooks I'm used to it going to 5V for a second and then switching to 20V after. But in this case it's instant 20v no hesitation

 

[kevinklinkmuller]

the only one that bootloops the amp meter occasionally is U3200...

 

[2informaticos]

The random behavior must be caused by corrosion.

When you connect the charger, should send 5V in the first moment.
SMC will decide to switch to 20V, usually 3-5s later.
Disconnect the battery, when you want to check the charger port behavior.

 

[kevinklinkmuller]

Ok, I fixed the board. For those reading here's what caused all these very strange issues... R7990 was blown. 5K ohms (supposed to be 0 ohms). Replaced that and bam!

Thank you 2informaticos for your help!

 

[2informaticos]

Thanks for feedback.
Do you mean R7900?
I can't find R7990.

 

[kevinklinkmuller]

Whoops, that's the one

 

[kevinklinkmuller]

Crap, Touch Bar doesn't work on this.

 

[2informaticos]

You should test with known good touchbar; its one may be damaged by liquid spill.
Also inspect touchbar flex and MLB connector for corrosion.

 

[kevinklinkmuller]

Will it just work out the box or will it have to be reset and all that?

 

[2informaticos]

New one should work.

 

[kevinklinkmuller]

Just tested new Touch Bar and doesn't work

 

[2informaticos]

Did you check MLB connectors?
Need to measure some voltage and signals; with touchbar connected, of course.

 

[it-solve]

Ok, I fixed the board. For those reading here's what caused all these very strange issues... R7990 was blown. 5K ohms (supposed to be 0 ohms). Replaced that and bam!

Thank you 2informaticos for your help!

How did you spot it? Did it have a visual change or indications? It's on PP3V3_G3H_RTC line

 

[kevinklinkmuller]

How did you spot it? Did it have a visual change or indications? It's on PP3V3_G3H_RTC line

Visual, it was pretty lucky. Was frustrated with the board. Could't find anything wrong so I checked basically every component under the scope. This one was brown

 

[kevinklinkmuller]

Did you check MLB connectors?
Need to measure some voltage and signals; with touchbar connected, of course.

Ended up being a burn mark on L5111, replaced and Touch Bar is back WOOOO

 

[2informaticos]

Thanks for feedback.
It helps us to understand what kind of failure components can cause touchbar issues.