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What am I missing...... apart from PPBUS_G3H and PP3v42_G3H

R

RESQ-MYTECH

New member
OK, 820-2879-B. No power. No Charge LED. No PP3V42_G3H or PPBUS_G3H.
I am using a 80w Adapter.
OK U6900
Pin 1 0.003v
Pin 2 0.001v
Pin 3 0.000v
Pin 4 0.001v
Pin 5 0.033 to 0.053v

C6908
Pin 1 0.089v
Pin 2 0.000v

C6905
Pin 1 16.60v
Pin 2 0.000v

F6905
Pin 1 16.60v
Pin 2 16.60v

R6929
Pin 1 0.031v
Pin 2 0.026v

U6901
Pin 1 0.024v
Pin 2 0.024v
Pin 3 0.008v
Pin 4 0.001v
Pin 5 0.021v

I have changed U7000, I dont know why... seemed like a good idea. Basically there was a little corrosion around it and no PP3V42_G3H at pin 12.

I have a 5.043v feed @ PP5V1_CHGR_VDD and PP5V1_CHGR_VDDP on Pins 19 & 20 respectivly on U7000. I also have 16.6v at Pin 2 on U7000

Now, I am also a little confused, the 80w charger states on it 18.5v @ 4.6A and 16.5v @ 3.6A yet at the DC in board and at the fuse F6905 it is reading 16.6v yet the line states PP18V5_DCIN_FUSE which should be 18.5v. I have used this adapter on many MBP circa 2012 and it is an original.

I know something should be producing a 3.42v feed but I am completely brain dead as to what it is. I assume its U7000 but the likelyhood of having 2 duff.... maybe...
 
2informaticos

2informaticos

Administrator
Staff member
3V42 comes out from L6995 and is not dependent of PPBUS_G3H.
Check resistance to ground there and post voltages for U6990.
Also check resistance to ground at L7030 and post voltage at pin 3/U7000.
 
R

RESQ-MYTECH

New member
OK,
L6995
Pin 1 0.082v 19.11Kohms
Pin 2 0.074v 19.27Kohms

U6990
Pin 1 0.032v
Pin 2 0.077v
Pin 3 0.049v
Pin 4 0.064v
Pin 5 gnd
Pin 6 & 8 0.031v
Pin 7 NC

L7030
Pin 1 0.303v 12.9 Mohms
Pin 2 0.302v 14.5 Mohms

U7000
Pin 3 3.933v

Also, if it helps, nowhere on the board is getting warm.

Edit.... Whilst getting voltages from U6990, I noticed C6990 pin 1 was grey and looked a little sad, so I removed it and replaced it with another 10uf 25v cap. I now have 2.63v at pins 6 & 8 on U6990 and Pin 1 on C6990.

I am now getting the following:-
OK U6900
Pin 1 1.161v
Pin 2 0.001v
Pin 3 0.000v
Pin 4 1.154v
Pin 5 1.070 to 1.154v

C6908
Pin 1 1.161v
Pin 2 0.000v

C6905
Pin 1 16.60v
Pin 2 0.000v

F6905
Pin 1 16.60v
Pin 2 16.60v

R6929
Pin 1 1.154v
Pin 2 1.151v

U6901
Pin 1 1.114v
Pin 2 1.115v
Pin 3 0.000v
Pin 4 1.162v
Pin 5 1.154v

Retested
L6995
Pin 1 1.165v 18.70Kohms
Pin 2 1.164v 18.74Kohms

U6990
Pin 1 0.558v
Pin 2 1.164v
Pin 3 1.170v
Pin 4 1.165v
Pin 5 gnd
Pin 6 & 8 2.170v
Pin 7 NC

L7030
Pin 1 1.171v 4.113 kohms
Pin 2 1.171v starts at 2.72Mohms and drops

U7000
Pin 3 3.933v
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
R6905 is burnt.
Check for short on pins 6 & 8 of U6990 before change it.

For the future, measure resistance to ground on diode mode, red probe to ground; unless we specify ohm scale...
And you don't need to measure on both sides of a coil!!!
 
R

RESQ-MYTECH

New member
Sorry, thouhgt I had meter on diode...
Pins 6&8 when tested with red on gnd and black on either pin or pin 1 of c6990 or the probe point in between I get a quick beep and OL on the meter. I have gone around the other pins in diode mode with the black on pin 8 and touched the others with OL all around except pin 6 which as I expect no resistance and continual beep.

Tested R6905 and it shows no short to ground ( dont know why I did that, i think i like to hear a beep :) ). Resistance is 1.707 kohms . I do not have a 1 ohm resisitor to hand ( 1r0) but I have got a 1ohm ( 10Y) which going by my mate google should be OK, just slightly smaller. It reads 1.1 ohm, will this be OK?
 
2informaticos

2informaticos

Administrator
Staff member
It should work.
Please provide accurate information for the future.
Be patient when check diode mode in the mobo, if your DMM has also buzzer on the same scale.
It will shortly beep when charges a capacitor!
 
R

RESQ-MYTECH

New member
Thank you 2informaticos . I did try to provide as much as I could. I didnt realise at the time I was in resistance, I will make sure that I am in the right mode, should the need arise again. I will be back in work on Monday so I will update you then on the progress.
 
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