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A2179 liquid damage, after new battery 5v no power

R

Roan

Member
Someone came in with an A2179 which had a liquid spill which wasn't noticed until an hour later. Audio board, fan and battery were liquid damaged but the mainboard seemed fine. Tried to start up using only mainboard and screen which made for a very slow MacBook.
Replaced battery and connected trackpad/keyboard flex and worked nice and smoothly again.
Cleaned the rest and connected one by one, but after the audio board flex the laptop does not give 20v anymore
Removing this flex now doesn't change the situation. Its on 5v even with only adapter connected.
Checked voltages around CD3217: no PP5V_G3S
Checked around ISL95828: VCC no voltage, VIN 12.15 and jumping shortly to 11V every 3 seconds
Is this the symptom of a faulty fried ISL, or can the jumping be a symptom of the CPU trying to boot when there is 5v and no 20v?
 
Last edited:
R

Roan

Member
P5VG3S_EN also missing, could be due to T2 issues DFU or...? Not sure what lead to follow nor can I find any logical next steps when looking at the schematic (googling around for answers right now)
 
2informaticos

2informaticos

Administrator
Staff member
Did you replace audio board/flex?
A1932/2179 both suffer because of audio board corrosion.
Many times T2 gets damaged its data lines from J6100.

Check diode mode to ground at T2 lines on J6100.
Pay atention to pins 32 & 33; next to PPBUS_G3H.
 
2informaticos

2informaticos

Administrator
Staff member
I don't know how to interpret these values.
Usually, we post diode mode readings like 0.xxx.

BTW, check w/ and w/o audio flex/board connected.
 
R

Roan

Member
Measured again and I think it equates to this:
pin 33: 0.004 (actually not 0.000)
pin 22: 0.004

with board/flex connected
pin 33: 0.004
pin 22: 0.004

This probably means that the easiest way for the current to go to ground is through the motherboard meaning the T2? As the audioboard doesn't change anything
 
2informaticos

2informaticos

Administrator
Staff member
Yeah, classic failure on these boards; leakage from PPBUS_G3H to mentioned T2 lines.
Audio board corrosion is very dangerous...
 
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