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820-2936 no power; flashing orage/green very rapidly

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elcapitan

Member
Hey Guys, I got a 820-2936 that came in with no power and no water damage history. When I connect the charger to the macbook it flashes green and orange very rapidly. I checked the main power rails and got the following readings PPBUS_G3H 0.45v, PPDCIN_G3H 17.06v, PP3V42_G3H 0.02v. I did some inspection around U7000 and notice that im receiving 3.44v at CHGR_ACIN but I'm missing all the output voltages CHGR_AMON 0.004v, CHGR_BMON 0.003v, SMC_BC_ACOK 0v. My instinct tells me that u7000 is dead. Can this be the case? Should i check voltages anywhere else? This circuit always confuses me -___-

Thanks,
 
E

elcapitan

Member
No Title

dukefawks said:
You need to have a stable 3V42 first. Is there a short or low resistance to GND on 3V42 bus?
Click to expand...

No beep at probe 422 of PP3V42_G3H. If i put my meter in diode mode, my black probe on PP3V42_G3H and my red on GND it gives me the value of 0.260. Since i needed a stable 3v42 i decided to take some measurements on U6990. It looks like PP3V42 its not being produced by this ic.
 

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E

elcapitan

Member
No Title

dukefawks said:
What is the "ohm" resistance to GND on 3V42 bus not diode?
Click to expand...

Hello duke, thanks for your response. Sorry i didnt take the reading correctly. Do u mind telling me how tp take it properly? Is it suppose to be like the pic attached? If this is true, my reading is 0.569 ohms
 

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D

dukefawks

Administrator
I don't know how that meter works sorry. I only see you range set to Mohm. Maybe you should read the manual on it and figure out how a multimeter works first.
 
E

elcapitan

Member
dukefawks said:
I don't know how that meter works sorry. I only see you range set to Mohm. Maybe you should read the manual on it and figure out how a multimeter works first.
Click to expand...

Thats lame which one do you use? This is the same multimeter we used at his class _- just trying to learn
 
larossmann

larossmann

Administrator
Staff member
the meter is going to say no letter, k or M on it.

think of this like drugs.

100k = 100 kilos = 100 thousand

M is million

so if you see a number with no letter, that's it. 5 ohms.

if you see a number with a k, that's the number times 1000

if you see a number with an M, that's the number times 1,000,000.

so 0.569, with an M, I would guess is 569,000 ohms, but this is a guess since I did not see if it was in that mode when you made the measurement.

If we make guesses as to what you measure we will be giving you advice on guesses, and that would be shit.

To be clear, we will answer questions and give advice based on answers, but we need to be able to get answers to these questions, and at the risk of being a dick - we expect multimeter proficiency by the time you've signed up. same with soldering, some threads here are asking "how do I bring the signal from X to Y?" and when we say run it there they say "how?" - we need you to be at the level of knowing what that means! if this means reading the manual for the tool, then this is what I'd suggest doing!

This will be covered in a sticky eventually.
 
E

elcapitan

Member
Thanks for the clarification louis. Was just confused; sometimes i over think stuff. To answer dukes question my resistance to ground on pp3v42_g3h is 569 ohms.
 
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dukefawks

Administrator
569 ohm is waaaay to low. It also is not low enough to find a component heating up by injecting 3V.

I would go ahead and inject 3.4V on the bus and see if you get a stable green light. An external power supply should be able to deliver enough current to compensate for the 569 ohm load. Once you have a green light we can see if there are more clues to what may be causing the low resistance.
 
E

elcapitan

Member
No Title

dukefawks said:
569 ohm is waaaay to low. It also is not low enough to find a component heating up by injecting 3V.

I would go ahead and inject 3.4V on the bus and see if you get a stable green light. An external power supply should be able to deliver enough current to compensate for the 569 ohm load. Once you have a green light we can see if there are more clues to what may be causing the low resistance.
Click to expand...

So i have manage to get PP4V42_G3H (3.46v) but now Im missing PPBUS_G3H (0.30v). I have 17.08v at PPDCIN_G3H. When I connect the charger to the macbook I get a fainted green light. My resistance to ground on PPBUS_G3H on the bad board is 18.05 mega ohms . It looks like my problem might be U7000, Q7030, Q7035. I have taken some measurements on u7000 and im missing all the output voltages. I think ill go ahead and replace this. I have attached a pic of the u7000 area
 

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larossmann

larossmann

Administrator
Staff member
1) How did you bring back PP3V42_G3H?

2) What do you get on CHGR_ACIN of ISL6259?

3) What is the resistance of R7005?

4) What voltage do you measure on CHGR_DCIN?

5) What is the resistance between pins 17/18 of U7000?

6) What is the resistance between pins 27/28 of U7000?
 
E

elcapitan

Member
larossmann said:
1) How did you bring back PP3V42_G3H?

2) What do you get on CHGR_ACIN of ISL6259?

3) What is the resistance of R7005?

4) What voltage do you measure on CHGR_DCIN?

5) What is the resistance between pins 17/18 of U7000?

6) What is the resistance between pins 27/28 of U7000?
Click to expand...

Thanks for the help guys :) Let me know if you need me to take any other measurements.

1) Not sure. It just appeared before following dukes suggestions of injecting 3.42v from a external PSU. I'm happy to say that I have PP3V42_G3H at L6995. Green light appears dimmed thou.

2) I get 3.81v at CHGR_ACIN of ISL6259

3) 431 Ohms

4) Im measuring the voltage that is coming from the adapter and going into ISL6259.

5) 3.3. Ohms

6) 20.3 Oh
 
E

elcapitan

Member
dukefawks said:
Number 3 not make you wonder?? Oh and ISL may be dead too then
Click to expand...


Hey Duke, I finally got a solid green light after after replacing U7000. The only crappy part is that my fan doesn't spin. I re-measured everything and notice that PPBUS_G3H was only 2.26v instead of 12.8v. Any idea what can be causing this? can a short in a different power rail cause the voltage to drop that low? I will keep trying to check the schematics and figure out the problem. Thanks for your help :)
 
E

elcapitan

Member
larossmann said:
Did you replace R7005? It's specced at 20 ohms, and you measured 431 ohms.
Click to expand...

Yes I did Louis. It's value is 19.6Ohms (R7005). Here is a recap of my readings after replace ISL6259 (U7000) and R7005. My U700 came from a functional donor board. At the moment, my board (820-2936) has a solid green light with no power. Any idea what can be bringing my PPBUS_G3H? I check the voltage at Pin 1 of L7030 and I got 2.35v

PPBUS_G3H 2.35v
PPDCIN_G3H 17.06v
PP3V42_G3H 3.46v

U7000 Pin3 (ACIN) 3.72v, Pin 23 (CHGR_PHASE) 2.30v, Pin 9 (CHGR_AMON) 0.03v, Pin 15 (CHGR_BMON) 0.08v, Pin 14 (SMC_BC_ACOK) 0.63.

The resistance between pins 17/18 of U7000 is 3.6 Ohms

The resistance between pins 27/28 of U7000 is 20.1 Ohms
 
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