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[SOLVED]820-3115 no green light ADAPTER_SENSE missing

ytesfay80

ytesfay80

Member
I got this board that had no damage anywhere else besides a corroded U6900. I was and still am getting just a dim green light on the charger and I am using a genuine 85W charger.

I have replaced the J6900 port along with U6900 and still I get 0.01v on ADAPTER_SENSE.
I do get 16.89v on both sides of F6905 and 3.46v on Pin 1(SMC_BC_ACOK_VCC) of U6900.
PPBUS_G3H is 12.56v.

On Pin 5 of J6900(ADAPTER_SENSE) I get 0.617v in diode mode.

I plugged in a fake charger I had laying around and I was getting 0.77v on ADAPTER_SENSE. and around 18v on Pin 1 of J6900.
 
ytesfay80

ytesfay80

Member
I get 3.31v on SMC_BC_ACOK.
R6929 measures the correct 2k ohms and shows 3.46v on both sides of the resistor.
 
D

dukefawks

Administrator
So SYS_ONEWIRE is at 3V, the ADPATER_SENSE must be too. Could be dead U6900 again or short on ADPATER_SENSE.
 
ytesfay80

ytesfay80

Member
I replaced U6900 again along with R6929 and I still get no green light. The only difference is that ADAPTER_SENSE is now at around .07v instead of the .01v it was before.
There is no short on ADAPTER_SENSE. I still get around 0.61v in diode mode on Pin 5 of J6900.

Could it be that both of the DC-In boards I have used are bad?

Also, is it normal for F6905 to be showing 16.9v when the schematic says 18.5v?
 
ytesfay80

ytesfay80

Member
With the DCIN board inserted into j6900 I get around 1.2Megaohms on resistance to ground on ADAPTER_SENSE.

I've plugged in 3 different DCIN boards and they all show a dim green light. One of them showed as high as 0.15v on ADAPTER_SENSE and slowly goes down from there.
 
ytesfay80

ytesfay80

Member
I have 3.46v on PP3v42.

I removed the heatsink to ultrasonic the board and I saw that C4908 was corroded and the cap was damaged on the 3v42 side. I replaced that cap and ultrasonic'd the board. When I plug in one of my DCIN Boards now ADAPTER_SENSE shows around .90v and keeps fluctuating slowly to as high as 1.9v

I did see one or two probe points around the SMC were discolored so I'm not sure if corrosion under the SMC could be causing this.
 
J

JohnB8812

New member
Ok so as Duke asked what is your resistance to ground on ADAPTER_SENSE? If your light is intermittent, I would guess crap under the SMC could be causing the issue or a dead SMC. Is the light intermittent or is it just dim?
 
ytesfay80

ytesfay80

Member
1.2Megaohms on resistance to ground on ADAPTER_SENSE.

The light is dim always no matter which DCIN board I plug in.

Update: That was the resistance I was getting previously when duke asked but now when I measure I get around 1.85Mohms.
 
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D

dukefawks

Administrator
OK lets start over and make sure we are measuring correct things here. I need to voltage on ALL pins of U6900 and resistances to GND with a magsafe board connected.
 
ytesfay80

ytesfay80

Member
U6900
Pin 1 - 3.46v
Pin 2/3 - 0v
Pin 4 & 5 - Started around .5v and slowly went down towards .35v

It's unusual that Pin 4 is showing the same voltage as ADAPTER_SENSE but Probe 1166 and Pin 1 of R6929 is 3.46v.
There is no continuity from Pin 4 to Pin 5 nor from Pin 4 to Probe 1166

U6900 Resistance to ground
Pin 1 - 1.85Megaohms
Pin 2 - 0ohms
Pin 3 - OL unconnected
Pin 4 - 1.83Megaohms
Pin 5 - 8.3 Megaohms
 
ytesfay80

ytesfay80

Member
Okay I ran a wire to the probe point and now I get a green light on the charger. The only thing is now that the board doesn't turn on.
I get 12.55v on PPBUS_G3H and I get correct voltages on PP5v_s5, PP3v3_s5 and PM_SLP_S4_L.
 
ytesfay80

ytesfay80

Member
Yes I plugged in a battery keyboard and trackpad. The light turns orange after a couple of seconds but no fan spin and nothing happens when the power button is pressed.
 
ytesfay80

ytesfay80

Member
C1802/03 are both 3.31v. The clock chip didn't have any corrosion around it.

I measured and got some more voltages.
PP3v3_S3 and PP3v3_S0 are both present.
PP5v_S3 and PP5v_S0 are both showing around 2.55v

Also, with the charger plugged in for a little while I can feel U1800 getting warm but I don't feel U1000 getting warm but that could be because it has a heatsink on it.
 
ytesfay80

ytesfay80

Member
Update: I did some troubleshooting and thought replacing U7200 would fix this but it didn't.
I get correct voltages on Pins 8, 13, 16 and 17 of U7200.
I get 0v on Pin 1(P5VS3_ENTRIP) and 0.90v on Pin 6. Somehow I still get 2.55v on L7260 even though there is 0v on Pin 1 of U7200.
There is 0v on Pin 2 of Q7221 and 0v on Pin 2 of R7913 while Pin 1 of R7913 is 3.4v.
 
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