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820-4924-A Missing PPBUS_G3H

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DaltonJr.

New member
Hi,

i have mannaged to screw two 820-4924 boards somehow. Both had some power issues, not working from battery... so i replaced U7100 and after replacement there was no PPBUS_G3H any more. Chips are new and soldered with hot air. I get green and orange light. There is power on pins 1 and 3 of D7005, but nothing on pin 2, also there is no power on output pins of Q7180. I wonder if there is possible damage that i could have done with the heat, replacing u7100? because same thing happened with two boards. I dont know what to look for anymore, everything looks ok.

Thank you for any help!
 
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DaltonJr.

New member
Yes, Mac was working, but just with power supply attached, thats why i replaced U7100. So PPBUS was surely there before...
 
2informaticos

2informaticos

Administrator
Staff member
Almost sure bad solders on U7100.
For new chip always apply leaded solder on its pads before place it on the board.
Now post resistance to ground on several points around U7100, pins 2, 4, 19, 20, R7120, F7140.
Do not power up the board again yet.
 
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DaltonJr.

New member
I have applied solder on the solder pads on the board.. and checked after soldering, joints look all good.

I have checked for resistance on points you suggested:

PIN 2 90kohm

PIN 4 600kohm

PIN 19 1,2Mohm

PIN 20 500kohm

R7120 650kohm

F7140 On Pin 2 i get around 60 ohms and slowly dropping or in diode mode i get value 425. Pin 1 is 2,5kohms.
 
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dukefawks

Administrator
If pins 1 and 2 of F7140 are different then at least the fuse is blown....measure continuity of the fuse.

If all you did was change U7100 then it is most likely bad soldering, wrong orientation or killed the chip.
 
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DaltonJr.

New member
You were right... i have replaced U7100 again and now it works again and i am back to the primary problem, it still works only with charger attached. It sees battery, but it wont work from the battery. I have replaced Q7155, but it is still the same. Any suggestions?

Thank you for support.
 
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DaltonJr.

New member
Battery status is Good, 234 cycles and it has 96% capacity. On battery simbol there is message “Battery is not charging”.

I wonder if this has something to do with a water damage that was around U3210 and U3400? I replaced 2 capacitors there and recovered a burned connection to the C3286. I will replace a few capacitors there that look a little fishy...

Now i also noticed click of the trackpad is not clicking all the time... as it would lose power every few seconds.

Voltage on pin15 of U7100 is 0,2v.
 
2informaticos

2informaticos

Administrator
Staff member
"Voltage on pin15 of U7100 is 0,2v."
Did you measure with both battery and charger connected?
Looks like battery is charging...

Check R7151/52.
If battery is not really charging, that voltage should be less than 0.05V I think.
 
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DaltonJr.

New member
0,2V on pin15 was measured with only charger connected. I will try with the battery too, if it is possible to connect it... and make a measure at the same time. Tomorrow i will make suggested... Thanks!
 
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DaltonJr.

New member
Ok, i carefully replaced U7100 again and then i got 19,9V on ppbus_g3h. I decided to replace few capacitors that looked a little suspicious from the water damage and now the charger is somehow shorted. When i connect the charger it sparks on second pin and there is no light on charger. I removed U7100, but it is the same. I checked few capacitors that i replaced, they are not shorted... still sparks on power connector when connected to charger.
 
2informaticos

2informaticos

Administrator
Staff member
Seems that you are using fake charger.
An original Apple one, will not power up the board if detects leakage/overload I think...

Check all MOSFETs from charger circuit.
I suspect shorted Q7130, on high-side.
Be sure C7125 is still there, and pin24 of U7100 is properly soldered...
 
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DaltonJr.

New member
Hi again,

Shorted charger is solved, q7130 was shorted. I use original 85w.

"Check resistance between pins 17/18 and 27/28 of the ISL" - There is no resistance.

R7151/R7152 to R7150, resistors are ok, all traces are good.

C7125 is ok, but only around 4v there.

Now i have green/orange again, at C7105 there is 16,7 volts and around 4v at F7140, not steady, seems pulsing.
 
2informaticos

2informaticos

Administrator
Staff member
"between pins 17/18 and 27/28 of the ISL" - There is no resistance."
I refer to resistance value on 200ohm scale between these pins!!!
 
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