SMC Issue on MBP 13 - Hardware Troubleshooting Guide

[cmdrdata]

Ok, I have replaced the resistor with a new one. That was fun for my first solder job. Little tiny guy! 0805 package 1ohm. This is R6905 on the G3HOT.

I know have on the LT3470A(U6990):
Pin 1, 2 = .63v
Pin 3 = 1.98v
Pin 4 = .70 v
Pin 6(VIN) = 16.17v
G3HOT = .63 before i replaced the R6905 I Had 1.16v on G3HOT
I need help figuring this out from here. I have No magsafe lights at all.
Obviously no power on at all.
How do I determine if the LT3470 is bad, or where do I go from here?

Also, I have no power getting to the battery connector.

According to the component spec, FB input which is pin 1 should be 1.25v to maintain the 3.42v output voltage. This is what it says: FB (Pin 8/Pin 1): The LT3470 regulates its feedback pin to 1.25V. Connect the feedback resistor divider tap to this pin. Set the output voltage according to VOUT = 1.25V
(1 + R1/R2) or R1 = R2 (VOUT/1.25 – 1)

So the fact that you're getting .63v on pin 1 is indicative that the G3HOT is overloaded (a short somewhere in the output side, or the divider resistors R6995-R6996 is not the correct value, or the LT3470 is bad.

You will not get magsafe status correct until G3HOT is 3.42v because this is power source for the SMC. Since SMC is not being powered, it cannot talk to the magsafe.

 

[mac-n-sauce]

According to the component spec, FB input which is pin 1 should be 1.25v to maintain the 3.42v output voltage. This is what it says: FB (Pin 8/Pin 1): The LT3470 regulates its feedback pin to 1.25V. Connect the feedback resistor divider tap to this pin. Set the output voltage according to VOUT = 1.25V
(1 + R1/R2) or R1 = R2 (VOUT/1.25 – 1)

So the fact that you're getting .63v on pin 1 is indicative that the G3HOT is overloaded (a short somewhere in the output side, or the divider resistors R6995-R6996 is not the correct value, or the LT3470 is bad.

You will not get magsafe status correct until G3HOT is 3.42v because this is power source for the SMC. Since SMC is not being powered, it cannot talk to the magsafe.

Yes, thank you. So if i check the resistor values at R6995-R6996 and they are fine then I have a bad LT3470. Without removing those resistors, can I just check for equal voltage out of both ends of them or do I need to pull them off the board. I know I can measure ohms with my multimeter, but doesn't it sometimes give inaccurate readings based on what is on the line?
Do I just measure them with the board unplugged and drain power in any connecting capacitors?

Thanks for the reply by the way. I have been stuck in this for a while.

 

[jebarne]

Macbook Unibody

1. This is the single most informative and useful thread I have ever seen on a message board. Thanks to all who have contributed. I'm a moderately technical person (I've replaced screens, cards, antenna, power supplies etc, but never fixed components. I would never start soldering on a board) so your expertise makes attempting a repair like this doable for a person like me.

2. It is so common for Apple to blame an issue on a bad logic board and the average person has no way to verify it. At my company, a customer can send us a mother board, we plug it into a test chassis and run an integrity test on it which details failures at the component level. I'm surprised someone doesn't have a logic board verification service where you could fedex your board, have it tested and fedexed back, as it would lead to the potential to repair boards, or even sell replacement boards.

3. My daughter spilled a coke into her macbook unibody around 6 months ago and I took it apart last night. Symptoms very similar to what is listed here. Power supply light doesn't go on. Battery won't charge etc. When I took it apart, all the coke was contained by the black plastic keyboard cover except for over the dvd player where it seeped onto the top of it, but no apparent spill over. There is zero sign of damage, dirt, grime etc on the logic board or anything close to it. The layers of the keyboard (keys, frame, cover) were totally stuck together. I'm just going to get a new upper case with keyboard rather than try to clean this because it takes so long to assemble, disassemble for each test.

Does anyone have experience successfully cleaning a keyboard and returning it to proper working order?

Any other things I should look for to verify that the logic board isn't damaged? getting a new logic board is cost prohibitive.

Thanks,

jb

 

[mac-n-sauce]

1. This is the single most informative and useful thread I have ever seen on a message board. Thanks to all who have contributed. I'm a moderately technical person (I've replaced screens, cards, antenna, power supplies etc, but never fixed components. I would never start soldering on a board) so your expertise makes attempting a repair like this doable for a person like me.

2. It is so common for Apple to blame an issue on a bad logic board and the average person has no way to verify it. At my company, a customer can send us a mother board, we plug it into a test chassis and run an integrity test on it which details failures at the component level. I'm surprised someone doesn't have a logic board verification service where you could fedex your board, have it tested and fedexed back, as it would lead to the potential to repair boards, or even sell replacement boards.

3. My daughter spilled a coke into her macbook unibody around 6 months ago and I took it apart last night. Symptoms very similar to what is listed here. Power supply light doesn't go on. Battery won't charge etc. When I took it apart, all the coke was contained by the black plastic keyboard cover except for over the dvd player where it seeped onto the top of it, but no apparent spill over. There is zero sign of damage, dirt, grime etc on the logic board or anything close to it. The layers of the keyboard (keys, frame, cover) were totally stuck together. I'm just going to get a new upper case with keyboard rather than try to clean this because it takes so long to assemble, disassemble for each test.

Does anyone have experience successfully cleaning a keyboard and returning it to proper working order?

Any other things I should look for to verify that the logic board isn't damaged? getting a new logic board is cost prohibitive.

Thanks,

jb

Keyboards are relatively cheap to purchase. Around $25.00 on eBay. The power button is connected to the keyboard that is why it will not turn on(i am sure it shorted). The keyboard has around 60 small phillips screws. So removing it is tedious. You can disconnect the the keyboard cable and short the G3HOT with a small flat head screwdriver to power the board on.(on a 13" MBP see photo)

HOWEVER------>IF YOU DID NOT TAKE THE LOGIC BOARD OUT AND LOOK ON THE OTHER SIDE OF THE BOARD-DO NOT TURN IT ON. Coke is very corrosive and will cause more damage to components when you power it up.

If it is a 15" then you short pin 5 of the keyboard connector to ground to start it up.(see photo) paper clip works well.

Good luck, let us know how it goes.

 

[mac-n-sauce]

CMDRDATA:

I have removed the LT4370
If I have the locations correct then my two resistors appear to be bad

R6995 = 128k
R6996 = 10k
this with and without the LT4370.

Would I replace the resistors then try my luck with the LT3470 still being good, or just replace them all?
Also, can anyone confirm that I do indeed have the right location for these resistors?

Does anyone know where we can by board view files of the logic boards.

This is the 2010 13" MBP

 

[cmdrdata]

Yes, thank you. So if i check the resistor values at R6995-R6996 and they are fine then I have a bad LT3470. Without removing those resistors, can I just check for equal voltage out of both ends of them or do I need to pull them off the board. I know I can measure ohms with my multimeter, but doesn't it sometimes give inaccurate readings based on what is on the line?
Do I just measure them with the board unplugged and drain power in any connecting capacitors?

Thanks for the reply by the way. I have been stuck in this for a while.

The LT3470 have a design limit of 350mA max (I think), and typical load for this unit should be no more than 200mA. So if the load on the chip is greater than that, then it will be unable to regulate to 3.42v and most likely gives a lower voltage with heavier than normal loading. There is no easy way to isolate the load, so I can't tell you how to check if the LT3470 is bad or not. G3HOT must always be 3.4v with magsafe only, battery only or both connected.

 

[CMDALTRP]

MBP mid 2010 i5 power-up issue

Hi folk.. I'm working on a repair of a MLB (mid 2010 15" i5), I hope it is okay ask a question regarding this. Perhaps some body have seen the problem.

I already repair the PSU/charger ISL6259A chip, changing FET, chip and a couple of resistors, and it is almost back in business ;-)

It will boot with magsafe connected (also charge) without battery.

If I hold power-on for 5 sec it will boot in any configuration.... as far as I remember it is the EFI load command.

PRAM and SMC reset has been done, also tested with other battery. Magsafe is the right one (original and brand new).

Light in magsafe is turning green/orange correctly.

If I boot and run ASD no error is showing.

When comparing with a working board it seem okay.

Also tested other signals like power good etc.

Any clues?

Reason found:

Found the problem, broken track to the current measuring resistor! Just like the picture somewhere...

Just check the voltage on pin 15 you should have approx 1V when running on battery. If you got approx 5V something is wrong with R7050-52 or tracks.

And always check the small resistors <100 ohm around the the 6258/6259

 

[cmdrdata]

CMDRDATA:

I have removed the LT4370
If I have the locations correct then my two resistors appear to be bad

R6995 = 128k
R6996 = 10k
this with and without the LT4370.

Would I replace the resistors then try my luck with the LT3470 still being good, or just replace them all?
Also, can anyone confirm that I do indeed have the right location for these resistors?

Does anyone know where we can by board view files of the logic boards.

This is the 2010 13" MBP

I think you have the wrong resitors measured. The top of R6995 goes to pin 2 pad of the LT3470. The junction of the two resistors goes to pin 1 of the LT3470. Your annotation didn't seem to match what I think it should be. The bottom of R6996 should be ground.

 

[mac-n-sauce]

I think you have the wrong resitors measured. The top of R6995 goes to pin 2 pad of the LT3470. The junction of the two resistors goes to pin 1 of the LT3470. Your annotation didn't seem to match what I think it should be. The bottom of R6996 should be ground.

Yes, you don't miss anything do you! That is awesome. The values are correct I just have the R6996 and R6995 backwards.

Would you agree though that these are both bad then?

 

[jebarne]

13" Macbook

Keyboards are relatively cheap to purchase. Around $25.00 on eBay. The power button is connected to the keyboard that is why it will not turn on(i am sure it shorted). The keyboard has around 60 small phillips screws. So removing it is tedious. You can disconnect the the keyboard cable and short the G3HOT with a small flat head screwdriver to power the board on.(on a 13" MBP see photo)

HOWEVER------>IF YOU DID NOT TAKE THE LOGIC BOARD OUT AND LOOK ON THE OTHER SIDE OF THE BOARD-DO NOT TURN IT ON. Coke is very corrosive and will cause more damage to components when you power it up.

If it is a 15" then you short pin 5 of the keyboard connector to ground to start it up.(see photo) paper clip works well.

Good luck, let us know how it goes.

Thanks so much. I had already disassembled the whole thing last night, including keyboard. I ordered one today and also cleaned the upper case with alcohol. I've been over every part of the logic board and don't see anything. So Keyboard first, assemble, hope the board still works, or disassemble and send off the board for a repair.

Thanks for the photos. I assume the mid 2009 is close enough to the 2008 to work if I have to go there.

Thanks,

jb

 

[cmdrdata]

Yes, you don't miss anything do you! That is awesome. The values are correct I just have the R6996 and R6995 backwards.

Would you agree though that these are both bad then?

My K6 schematic says that they should be 348K and 200K ohms respectively, thus if they are these values, the output voltage will be:

G3HOT = 3.42v = 1.25v x (200K + 348K) / 200K

Since you have the resistors measured at 128K and 10K, I expect the LT3470 cannot generate the correct output as:

1.25v (128K + 10K) / 10K = 17.25v and that is not possible since the input to the chip is between 12v (if battery powered) or 16.5 if magsafe powered and the chip just cannot handle that divider ratio. Easiest thing is to try is to replace both resistors. and see if that cured your G3HOT issue.

 

[mac-n-sauce]

My K6 schematic says that they should be 348K and 200K ohms respectively, thus if they are these values, the output voltage will be:

G3HOT = 3.42v = 1.25v x (200K + 348K) / 200K

Since you have the resistors measured at 128K and 10K, I expect the LT3470 cannot generate the correct output as:

1.25v (128K + 10K) / 10K = 17.25v and that is not possible since the input to the chip is between 12v (if battery powered) or 16.5 if magsafe powered and the chip just cannot handle that divider ratio. Easiest thing is to try is to replace both resistors. and see if that cured your G3HOT issue.

I just wonder if something else can be causing these values prior to getting there. Dadioh: any thoughts?

 

[Dadioh]

I just wonder if something else can be causing these values prior to getting there. Dadioh: any thoughts?

Sorry. Have been very busy with house renovation and haven't checked here in a while. Let me try and look at your question and get back to you later this week.

 

[Dadioh]

I have a MacBook pro 13 logic board that I rescued from a liquid spill. Several components and traces required replacement. It is now working and passing extended apple hardware test.... But.... The fan insists on running on high speed even though temps are fine. The other clue is that of I run with only charger it is ok but istat only shows 3 temps in the menu. As soon as a battery is installed istat shows additional temps and fan slowly revs to 6000 rpm and stays there.

Does battery presence usually result in more sensors being displayed? Anyone have any ideas?

 

[mac-n-sauce]

Sorry. Have been very busy with house renovation and haven't checked here in a while. Let me try and look at your question and get back to you later this week.

I am a general contractor by trade. Specialize in residential remodeling. You have been a great help in this forum. If you need and info with your remodeling project let me know!

 

[mac-n-sauce]

Macbook Pro 13" 2009

Ok, folks. I have another fun mac that had some slight liquid damage.

Had to clean and replace battery light indicator.
Powers on works completely.
See battery
Will not charge battery.
No lights, green or orange on magsafe charger.
Getting 16.75v in from magsafe.
Any thoughts on what is keeping it from communicating to charger?
I am guessing it has to do with the BIL Connector J6955 but not sure how to check for communication to the charger or if this is the issue at all.

 

[Dadioh]

Ok, folks. I have another fun mac that had some slight liquid damage.

Had to clean and replace battery light indicator.
Powers on works completely.
See battery
Will not charge battery.
No lights, green or orange on magsafe charger.
Getting 16.75v in from magsafe.
Any thoughts on what is keeping it from communicating to charger?
I am guessing it has to do with the BIL Connector J6955 but not sure how to check for communication to the charger or if this is the issue at all.

Start at the charger ic Isl6258 just north of right side of memory slot. Pin 14 will be 3.4v if it is happy. Pin 1 is north east corner (battery facing you, hinge away from you). Count counter clockwise 7 pins per side. So pin 14 is southwest corner. Careful probing it not to short it although pin 13 is unused iirc. If you don't have 3.4v (likely 0v) then charger ic may be bad.

 

[mac-n-sauce]

Start at the charger ic Isl6258 just north of right side of memory slot. Pin 14 will be 3.4v if it is happy. Pin 1 is north east corner (battery facing you, hinge away from you). Count counter clockwise 7 pins per side. So pin 14 is southwest corner. Careful probing it not to short it although pin 13 is unused iirc. If you don't have 3.4v (likely 0v) then charger ic may be bad.

thank you, will check and get back to you. Is that the common problem for no battery charge?
Also, what is the easiest way to get the lvds 30 pin connector off? Solder flood? Mine is bad and I need to change it out. Know of any videos? I have been searching but can not find any.

 

[Dadioh]

thank you, will check and get back to you. Is that the common problem for no battery charge?
Also, what is the easiest way to get the lvds 30 pin connector off? Solder flood? Mine is bad and I need to change it out. Know of any videos? I have been searching but can not find any.

Bad charger ic is common. I keep about 5 on hand at any given time. Isl6258 for 2008/2009 models. Isl6259 for 2010. Digikey and Newark have been out of stock lately so I bought my last batch on eBay.

I remove the lvds connector with my hot air tool. Works fast but destroys the plastic but it is getting thrown out anyway. Clean the pads and place new connector and then tack the two end pins. Then solder pins one at a time.

 

[mac-n-sauce]

Thanks again.
Try L2order.com they carry the chips and are usually in stock. Easy to deal with. You can buy in bulk as well.

 

[mac-n-sauce]

Start at the charger ic Isl6258 just north of right side of memory slot. Pin 14 will be 3.4v if it is happy. Pin 1 is north east corner (battery facing you, hinge away from you). Count counter clockwise 7 pins per side. So pin 14 is southwest corner. Careful probing it not to short it although pin 13 is unused iirc. If you don't have 3.4v (likely 0v) then charger ic may be bad.

Ok, pin 14 = 3.31v
Pin 10, 11 = 3.40v
Pin 2 = 16.55v
pin 27 = 16.26v

Have 12.57v at battery pins 7,8,9

guess it is not the IC?

 

[Dadioh]

Ok, pin 14 = 3.31v
Pin 10, 11 = 3.40v
Pin 2 = 16.55v
pin 27 = 16.26v

Have 12.57v at battery pins 7,8,9

guess it is not the IC?

Sounds like the charger is happy if pin 14 is 3.4V. Now need to check downstream where that signal converts to the signal to the magsafe. See attachment. I don't have a logic board handy to show you where the devices are but one of them is backside near the magsafe connector IIRC. I would need to stare at a board to remember the other.

 

[mac-n-sauce]

Sounds like the charger is happy if pin 14 is 3.4V. Now need to check downstream where that signal converts to the signal to the magsafe. See attachment. I don't have a logic board handy to show you where the devices are but one of them is backside near the magsafe connector IIRC. I would need to stare at a board to remember the other.

both appear to be functional.

U6900 on top by dc in says "ATC" on it.
Pin 1 Vcc1 = 3.41v
Pin 4 Int = 3.41v
Pin 5 ext = 16.75v

U6901 on bottom just west of LVDS says "R2" on it
Pin 1,2 in = 3.34v
Pin 4 "Y" = 3.41v
Pin 5 Vcc = 3.41v

 

[Dadioh]

both appear to be functional.

U6900 on top by dc in says "ATC" on it.
Pin 1 Vcc1 = 3.41v
Pin 4 Int = 3.41v
Pin 5 ext = 16.75v

U6901 on bottom just west of LVDS says "R2" on it
Pin 1,2 in = 3.34v
Pin 4 "Y" = 3.41v
Pin 5 Vcc = 3.41v

Pin 5 on U6900 should be around 3V. Is your DC in board ok? Have you tried a known good one?

 

[mac-n-sauce]

Pin 5 on U6900 should be around 3V. Is your DC in board ok? Have you tried a known good one?

You are really good!! Works like a charm, with a working dc in board.
Awesome!!!

Now I can get back to my real bad one.