A1708 020-00840 liquid damage, no power

Doubleu82

New member
Hi All,

let me start with introducing myself, I'm an electronics engineer working in software now for ASML. I started repairing macbooks (actually Louis videos triggered me ;-) ) from a hobby perspective now and then but it has grown since to 1 or 2 a week. My repair side carrier made it possible to invest in proper tooling (trinocular microscoop, JBC soldering, Quick hotair, HP multimeter, power supply with dual 30v5A, i5 hackintosh workstation from Aliexpress :-D


I'm working on a case (read rabbit-hole) for data recovery of an A1708 board 820-00840, i'll try to be as elaborate as possible (most from memory)

when I received the board it was doing absolutely nothing. I took some pictures of the corrosion and ultrasonically cleaned the board. this revealed some problem areas.
a lot of PP3V3_GH circuit was broken/gone, replaced some resistors and removed some caps. It works now (doesn't look very nice since i only had 0603 resistors laying around)

Screenshot 2020-08-01 at 13.05.56.pngScreenshot 2020-08-01 at 13.08.53.png
the gone pads are TPAD testpoints/via's, didn't bother fixing those yet

PP3V3_GH, repaired the circuit and now 3,4v present (when powered via F7000)
still no power via USB-C (stays at 5v 0mA, other port 5v 50mA and getting hot)
first replaced one CD3215 (the one getting hot) , still not equal mA, replaced second CD3215, now both equal. PPDCIN_3GH present at Q7030 (usb 5v 10mA)
I did not trust the U7000 (ISL) (weird impedance at Aux_det) so replaced it
now Aux det is 1,2v and R7015, R7016 measure ok.
now I get 5v at charger and 40mA cycling at both USB ports, but ISL still creates no PPBUS (12v3)

when I supply power to the battery terminal, (7v5) it takes 15mA and I measure this voltage also at F7000 (tried 10v, no change), PPBUS is than equal to the supplied voltage

SMS_RESET_R_L = 3,4v at R7072
PM_EN_P3V3_GH = 5v at R6999
SMC_AUX_OK = 3,4v at R7071
PP3V3_3GH_UPC = 3v3 at C3100 and C3200

Any clues where to look further?
 

2informaticos

Administrator
Staff member
First of all, welcome to the forum!

3V3_G3H is the only corroded area on the board?

STOP applying external voltage at F7000, or battery terminals!!!

Are you sure the new CD3215 chips are good?
Many fake/remarked chinese crap out.
Check for 1V1 LDO voltage on the powered USB-C port.
Do you get BUF_SMC_RESET_L too?

"power supply with dual 30v5A"
Forget it and get a simple 24V/20A, or arm one with DPS5020.
Many times mentioned WHY in the forum...
 

Doubleu82

New member
Hi,

thanks for the fast reply,

The ISL area was a bit corroded, after cleaning with IPA and a brush it looked ok. but replaced the ISL (ebay source) after measuring some wierd levels

I ordered two batches of CD3215, first 5pcs from ali that arrived after 2months dangling in a plastic bag wrapped in bubble foil (awful), and a set from ebay, nicely packed in a cut reel (15eu a piece). What would be a trustworthy source (available in EU) for the cd3215.

I'll have a look into the signals mentioned and get back to it
 
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