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820-3115 B No green light on Magsafe

2informaticos

2informaticos

Administrator
Staff member
"a slight flicker on MAGSAFE green light"
Don't you have steady green light now?

Check for pulse at pin 4 of both U2650/60.

Compare diode mode to ground at PPBUS_G3H with all big coils.
 
N

Neil250

Member
I have a green light but if you look very close it appears to be flickering ever so slightly and the fan is ticking like it wants to start but is not getting regular power.
 
N

Neil250

Member
I will try another charger as well.

Why did you ask to check pulse at pin 4 of both U2650/60?
How did you choose to look at that location.

Is it because it is getting inputs from so many the PWRGD lines ?
 
N

Neil250

Member
I had left the board untouched for 12 hrs and I was actually getting a steady voltage on PPBUS_G3H for a while with a steady 0.35 amp draw on 18.5V power supply. But still no fan spin.

I had no idea what was going on.

As I handled the board, the pulsing started again on PPBUS_G3H measured at F7040 pad 2.
Fan ticking like it wants to start.


WTF? Should I ultrasonic clean this board?

VOLTAGES

PPBUS_G3H: 12.57 pulsing


PIN 4

U2650: 0 - 0.45 V pulsing
U2560: 0 V - 0.45 V pulsing
Diode mode to ground




L7801: PIN 1: .562 V PIN 2: .562 V
L7220: PIN 1: .138 V PIN 2: .138 V
L7560: PIN 1: .001 V PIN 2: .001 V
L7550: PIN 1: .001 V PIN 2: .001 V
L7510: PIN 1: .001 V PIN 2: .001 V
L7630: PIN 1: .450 V PIN 2: .450 V
L7630: PIN 1: .009 V PIN 2: .009 V
L7330: PIN 1: .141 V PIN 2: .141 V
L7100: PIN 1: .007 V PIN 2: .007 V
L7220: PIN 1: 0.139 V PIN 2: .139 V
L9701: PIN 1: 0.438 V PIN 2: .438 V
L3895: PIN 1: 0.528 V PIN 2: .528 V

PPBUS_G3H: 0.455 V
 
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N

Neil250

Member
OK I removed U7000 and resoldered it
Good news is that handling the board does not result is the pulsing like it did before.

F7040 IS OUT

MAGSAFE SOLID GREEN
POWER SUPPLY: 18.50 V STEADY
0.37A STEADY DRAW ON POWER SUPPLY BUT NO PULSING!!!

PIN 1: 18.1 V
PIN 2: 18.08 V
PIN 3: 4.37 V


PIN 9: .03 V
PIN 12: 3.47 V

PIN 14: 3.33 V
PIN 19: 5.07 V
PIN 20: 5.04 V

PIN 26: 17.79 V
PIN 27: 18.03 V
PIN 28: 18.05 V

RES 27-28: 20.4 O
RES 17-18: 12 kO

R7010: 7.68 kO
R7011: 6.92 kO

R7085: 396 kO
R7086: 319 kO
R7020: 18.02V

L7030 (PAD 2) PPBUS_G3H: 12.56V
R7051: 12.50 kO
R7052: 0.4 O

ALL VOLTAGES STEADY AT THIS POINT

IF F7040 is placed back in circuit: pulsing starts

IF F7040 is removed in circuit: pulsing stops

Please note R7051 is way OFF.
 
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N

Neil250

Member
I will change R7051.

If R7051 was/is issue why is PPBUS_G3H stable without F7040 on the board but resumes pulsing when placed back?
Shouldn't PPBUS_G3H pulse regardless of F7040 being in place or not if R7051 was bad?

Just trying to understand the current sensing circuit functioning.

When I measured R7051 prior to initially changing U7000 5 days ago it was correct at 3 ohms.
I'm not sure how I messed that up.
 
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N

Neil250

Member
CHANGED R7051
MAGSAFE SOLID GREEN
POWER SUPPLY: 18.50 V STEADY
0.375 A STEADY (CURRENT DRAW STEADY BUT WENT UP AFTER R7051 CHANGED)

PIN 1: 0 V <--------------------------------------------- OK?
PIN 2: 18.22 V
PIN 3: 4.38 V


PIN 9: .03 V
PIN 12: 3.47 V

PIN 14: 3.26 V
PIN 19: 5.07 V
PIN 20: 5.04 V

PIN 26: 17.79 V
PIN 27: 18.03 V
PIN 28: 18.05 V

RES 27-28: 20.4 O
RES 17-18: 3.2 O


R7010: 7.68 kO
R7011: 6.92 kO

R7085: 396 kO
R7086: 319 kO
R7020: 18.02V

L7030 (PAD 2) PPBUS_G3H: 12.56V
R7051: 3.0 O
R7052: 0.4 O

ALL VOLTAGE STEADY
PPBUS_G3H STABLE AT 12.56V


IF F7040 is placed back in circuit: pulsing starts again

So frustrating
 
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2informaticos

2informaticos

Administrator
Staff member
SMC is not connected to PPBUS_G3H directly.
I want to help, but I don't really understand how you work on that board...
 
N

Neil250

Member
Good news.

Changed R/C7025.board now turns on!!..I get green light on magfsafe and fan spin
Stable PPBUS_G3H

LCD backlight not coming on.
 
2informaticos

2informaticos

Administrator
Staff member
You only needed two days to change mentioned components...

Missing image and backlight at same time?
Did you test external video?
Can you confirm USB activity at least?
 
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