A2289 Board 820-01987-A Dead?

[momoomar]

Re: A2289 Board 820-01987-A Dead?

Hey dbteckos. Sorry for the late answer since then I have bought another 820-01987 board and here with no signs of corrosion or other damage but it takes 200mA and 20V dont know why yet.. the old board are stock on DFU mode now and it only takes 80-96mA 20V

I measured the testpoint (beside J8401) for both board diode mode = Old board : 1.788 new board : 1.700

Here are some other measurements for old and new board

Ny board

L7270 = 14.30 ohm
L7210 = 4.30 ohm
L7220 = 4.30 ohm
L7410 = 3.93 ohm
L7420 = 3.93 ohm
L7702 = 43.3 ohm
L7030 = 2.68 Mohm
F7000 = 50 kohm both sides
L8102 = 27.33 ohm
L8100 = 0.46 kohm
L7690 = 1.6 Mohm
L7670 = 5.9 kohm
L8410 = 1.10 Mohm

Old board

L7270 = 13.7 ohm
L7210 = 2.50 ohm
L7220 = 2.50 ohm
L7410 = 3.66 ohm
L7420 = 3.51 ohm
L7702 = 24.3 ohm
L7030 = 2.26 Mohm
F7000 = 1.6 Mohm both sides
L8102 = 56.2 ohm
L8100 = 0.33 kohm
L7690 = 0.44 Mohm
L7670 = 0.40 Mohm
L8410 = 1.10 Mohm

[Stephen]

Re: A2289 Board 820-01987-A Dead?

I have an ultrasonic cleaner, I will try. What temperature and time settings do you recommend ?

Sorry just noticed this!

Temp for Ultrasonic cleaner for Logic board should be
66C
and timer needs to be 4 mins per cleaning cycle. You need to clean the board two times. One side for 4 mins, then flip it and clean for another 4 mins. Total of 8 mins of cleaning time.

After that you need to throw the board into a tub of 99% Isoproply Alchohol.

Make sure your Ultrasonic cleaner is using Distilled water and on top of that make sure you are using EC Cleaner from Branson. I would hope you are using a Crest Ultrasonic cleaner as well. Hope this helps!

[elektrosha]

Re: A2289 Board 820-01987-A Dead?

Had pretty similar (if not the same) issue as Kudeta. After doing throughout visual inspection for the 3rd time I discovered shorted capacitor C8103 and shot 0Ohm resistor R8154 next to it. After replacing both - logicboard is back to life. Hope it will help someone.

[Deluccia]

Re: A2289 Board 820-01987-A Dead?

I have a very similar issue myself.
Have a A2289 board that "boots" without battery at 20v 0.5A with trackpad, warm CPU and fan spin.

No display nor Touch Bar. Had liquid damage around U7420 and Q7065 mostly.

I wish there was a definitive check list of rails to test in order to determine what can irrefutably diagnose a major component failure.

I find I am good at locating offending components but I struggle to know if I'm always looking in the right places in terms of what is essential to be live and what isn't.

I will update my findings here this week