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820-00165-A no power no green light strange DC readings

waterchill

waterchill

Member
Hi, I have here this board on my desk and it have strange DC readings. No power no green light, complete dead. No water damage.

Voltages:

PPDCIN_G3H - 15,00V this should be 18,5v?

R7005 Pin 1 - 15,00v
R7006 Pin 1 - it starts with 0,7v and goes after a while below 0,2v

D7005 Pin 3 - 14,11v

L7130 - 0,176 on either side
L7095 - short on both sides.

U7090

Pin 1 - 0.58v
Pin 2 - 0.11v
Pin 3 - 1.18v
Pin 4 - 0.32v
Pin 6 - 14,11v
Pin 8 - 14,11v

Thank you
 
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waterchill

waterchill

Member
I have checked with thermal camera the U7090 is getting hot if plug in only the ac adapter. I have changed the U7090 but still same issue.Any ideas? I', still wondering why the PPDCIN is 15,00v and not 18,5v
 
2informaticos

2informaticos

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

"I', still wondering why the PPDCIN is 15,00v and not 18,5v"
Stop to make wrong assumptions!
Did you ever check with other charger?
That is the nominal charger voltage; depends by its specifications.

"L7095 - short on both sides."
Once U7090 removed from the board, did you check if still short there?
If yes, no reason to change it.
I bet your short is not caused by U7090.
Removing L7095 helps to see where the short remains; instead of removing U7090.

Can you post the exact ohm value of that short?
Usually voltage injection method helps to find the culprit; in case of pure short, or very low ohm value.
 
waterchill

waterchill

Member
Thank you for answer. I have just measured it looks like the short is gone when I unplug the I/O cable from the DC charger. If unplugged the numbers are on Pin 1 L7095 it is 83kohm and Pin 2 51kohm. If plugged in the readings are 0,7ohms and 1,2ohms on other side L7095. I have an other DC Board here but it is not from 2015 model it is from 2013 but it makes still the same short when I/O plugged in.
 
2informaticos

2informaticos

Administrator
Staff member
You should look at connectors layout before making such substitution!!!

Inspect LIO flex connectors for corrosion.
Also inspect J9500 pins under microscope.
 
waterchill

waterchill

Member
All connectors are fine, I have all cleaned no corrosion. All Pins also ok. The charger is also ok works great on macbook pro. I have noticed that I have accidently plugged in the LIO flex in the wrong way 😔 turned 180°. Now the short is gone even if plugged in but there are still 15,00v
 
2informaticos

2informaticos

Administrator
Staff member
I said the input voltage depends by charger type; what is not clear?
If you connect 45-60-85W model, will get different voltage, don't you think?

Do you get 3V42_G3H now?
 
waterchill

waterchill

Member
The 3V3_SUS is produced from U8020 but on the U8020 PP3V3_S5 is 0,00v. How can it be that the same line on the one side of the board is present and on the other not present?
 
waterchill

waterchill

Member
Ok I made a measurment fault. In OpenBoardview I had to tick the option "whole" because if search PP3V3_S5 it shows me all the other lines on the board with all prefixes even if I click on the PP3V3_S5, sorry my fault. So the 3V3_S5 is not present

Edit: The short to ground on C8020 Pin 1 is about 374ohm
 
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2informaticos

2informaticos

Administrator
Staff member
"PPBUS_G3H = 8,2v"
Communication fault between SMC and U7100.

"PP3V3_S5 = 3,3v
------------------
3V3_S5 is not present"
Really no voltage at L7560?
 
2informaticos

2informaticos

Administrator
Staff member
"PP3V3_S5 = 3,3v"
When and where did you get this?
Is impostant to post correct information.
Check if there appears voltage in the first few seconds, or pulses at least.

3V42_G3H and PPBUS_G3H still present?
Check SMC_PM_G2_EN, SMC_ADAPTER_EN and PM_BATLOW_L.
 
waterchill

waterchill

Member
2informaticos said:
"PP3V3_S5 = 3,3v"
When and where did you get this?
Click to expand...
I got this on C5126 Pin 1 but this is PP3V3_S5_AVREF_SMC

PP3V3_S5 = 0,00v on C8130 Pin 1 so this line is not present

After plug in charger 3V3_S5 raises slowly from 0,00volts to 14,7miliVolts in about 2 minutes, checked with oscilloscope

PP3V42_G3H = 3,42v is present on R7095 Pin 1

PPBUS_G3H = 8,2v is present on F7140 Pin 2

SMC_PM_G2_EN = 0,00v on R5198 Pin 1

SMC_ADAPTER_EN = 0,00v on R5185 Pin 1

PM_BATLOW_L = 0,013v on Q3000 Pin 3
 
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