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820-2915-B No power on with green light

A

Allstartek

Member
This repair started with no power on and no lights on the magsafe.

After reading through some threads and testing the power rails I replaced the U7000 and now I get a green light but no boot, fans etc.

I've gone back and forth so many times with the 1 wire and other voltages that I think I lost my mind completely.

Here is what I get now for voltages. I know this is a lot but I wanted to give too much info vs. to little.

Thank you,
Chris

J6900
Pin 1 - 16.82V
Pin 2 - 16.80V
Pin 5 - 3.42V

F6905 16.8V
C6905 16.83V

U6900
pin 1 3.43V
pin 2
pin 3
pin 4 3.43V
pin 5 3.43v

R6929 -3.43V
1.98K ohm

U6901
1 3.31
2 3.31
4 3.45
5 3.45

---------------------------------
G3Hot 3.43V
D6990
1 0v
2 16.01V
3 16.0V

C6990 15.67V

R6995
1 16.63V
1 15.12V
.986 Ohm
C6995
0 V

U6990
1
2 3.45V
3 15.13V
4 15.6V
5
6 3.42V
7 15.6V
8 3.7V
9 3.42V
10 3.2V

L6995 3.45V
C6999 3.42V
--------------------------

ppdcin_g3h

R6990 16.82V
C6990 15.89
R6995 16.6 - 15.65V

c6991 - 3.45v
c6995 3.34
c6994 3.45
L6995 3.445 3.445
c6999 3.45V

R7080 16.24 99k ohm
R7081 16.25v 61.5k ohm
R7020 -16.39v all 4 pins
R7021 16.4v
R7022 16.39v


r7085 16.83 381k (470k)
r7086 6.8V 296.5k (332k 1%)
d7005 16.8 - 16.8 --16.5
R7005 16.54 20ohm

R7001 5.0v

U7000
pin 2 dcin 16.43v
pin 3 acin 3.9v
pin 9 amon
pin 14 3.45v
pin 24 0v
pin 19 5.0v
pin 20 5v


Q7035
1 0
2 0
3 0
4 4.03v
5 0

Q7030
1 0
2 0
3 0
4 0
5 16.1v
 
A

Allstartek

Member
It's old and used and certainly looks like it. It has the soft rubber cables. It really does look authentic. I tried 2 others. 85W authentic Apple.

The biggest question I have is the 16.5 volts not 18.5.

Could this be the u7000 is a bad chip or I did a poor job placing it?
 
A

Allstartek

Member
I have tried 4 different 85W OEM chargers and 3 different magsafe DC power boards and I get the 16.5 volts from all of them testing at J6900
 
D

dukefawks

Administrator
I asked for SMC_ADAPTER enable, please explain what SMC_RX_L has to do with that? Test at R5085.

I bet you are using China special chargers, that say 85W but are just 60W ones.
 
A

Allstartek

Member
R5085 pin 1 is 3.43V

I've been repairing Macs for years (only recently component level) and I sell the chargers so please trust me when I say i know the difference. One of the chargers I used was my own from my MBP.
If need be, I will go to best buy and buy another brand new one.

At least this help me understand that I'm not entirely insane. :)
 
A

Allstartek

Member
So I put the logic board back into the system. I decided to try and do an SMC reset hoping for the best.

What I get is:
It charges the battery, the charge indicator is amber and charging.
I try to power it up and get the sound of the CD loading but no video (no the backlight isnt out) no indication other than the CD that the power button was pressed.
The SMC reset turns the charge light green briefly.
 
A

Allstartek

Member
Now I am back to no lights on the charger. I'll start back at square one and try again. I guess this is the pain and struggle of being a newbie........
Thank you for your previous help. I'm sure I'll be back with more questions.
 
A

Allstartek

Member
I have been working on this again after a couple of days away from it to clear my head... very frustrating.. The issue now is low voltage on Q7080 - CHGR_SGATE. I only get 1.6V on pin 26 of U7000. I have replaced U7000 2 times because it seems like this is where I lose the power.
On Q7080 I lose the power on the "Reverse-Current Protection" side.
Q7080 the Inrush-limiter side I get 16.09 volts. so this seems good.

Can you please offer me some ides?
Thank you.
 
D

dukefawks

Administrator
1.6V on pin 26 is great, it means it is turning on half of Q7080 at least. Same should happen on pin 1 so there is the problem. Either dead U7000 or Q7080 or some resistor/trace around U7000.
 
A

Allstartek

Member
Replace Q7080. I now have 5v that drops to 1.2v on Q7080, Replaced U7000 3rd time with one from another board. The new ones i have been using dont seem to make a difference.

Now I am back to having low voltage on pin 3 of U7000.
R7005 16.2v
R7051 1.2
R7052 1.3

R7021 1.2v
R7022 1.4v

R7010 has 16.3v on pin1 and 1.7v on pin 2..

I really feel like I'm just going in circles..

I replace R7010 and r7011 and c7010. The resistors because they would'nt read correctly in circuit. R7010 was 13.8ohm in circuit and ok out of circuit. R7005 was 28.2ohm in circuit and 20 in circuit.

*sigh*
 
D

dukefawks

Administrator
R7010/11 is a simple resistor divider and if you do the calculation it should have about 3.7V to U7000. Remove U7000 and I bet the voltage will come up to 3.7V. So Badly soldered or dead U7000 pulling ACIN down.
Green light should not be present at this time as ACIN is too low.
 
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