SMC Issue on MBP 13 - Hardware Troubleshooting Guide

[DjErase]

I typed wrong. The SCL and SDA lines are on pin 4 and 6. Pin 5 is a battery enable pin called SYS_DETECT, a "pull-down" signal to the battery to enable its output, consisting of 10KOhm connection to ground. So both pins 4 and 6 should have 3.4v when not pulsing.

If pin 6 is also 3.4v, then I'd look at the signal SMC_PM_G2_EN. This is a signal from the SMC power management that turn the system on when powered by magsafe or battery. Since the MBP works on magsafe, somewhere along the line a battery sense signal is not making it to the SMC thus it will shut down the system when ever magsafe is removed.

PS: I just re-read the message. When the battery is plugged in, pin 5 should be 0v, as it is being set to logic zero by the R6950, a 10kOhm resistor.
PPS: when you measured 11.5v on the fuse, I assume you are getting that with the magsafe unplugged, right?

Well I made a mistake too.

With or without Magsafe, I have 3,5Volts on pin 4 & 6. I have 0,3 V on pin 5.

I try to find SMC_P?_G2_EN but I don't find the U4900 H8S2117.

 

[DjErase]

I Give a battery to a friend yesterday and now it's fully charged.
I tried some tests:
1°) The test button with green light doesn't work, I was thinking that one light staid green but all are flashing 4 or 5 times and then nothing is staying green.

2°) I cannot start the MPB on battery but if I start it with the Magsafe and then remove the Magsafe it staid on the windows "DOS MENU WITH SAFE MODE" boot screen.

Well if someone has the clue .


Thanks.

 

[DjErase]

Last but not least : What is the chip indicated by the yellow arrow?

Thanks.

 

[mac-n-sauce]

MacBooK Pro 13" 2010 No boot/Power

Hello all! 24 pages of the most informative forum I think I have ever read!

<Dadioh,CMDRdata>
My macbook has no power or boot.
I have working mag safe/board and battery
ISL6258A pin 14 measures .17 without battery/ .67 with battery
G3Hot .25 without battery/ 0-.97 with battery(starts at .97 and fades to 0)

Checked the voltage from magsafe to battery

I have attached a picture of what I found. I have read all 24 pages of the post and still am not sure how to proceed.

Any help is appreciated.
Thanks

 

[mac-n-sauce]

Last but not least : What is the chip indicated by the yellow arrow?

Thanks.

Here is a close up if it helps anyone to identify.

 

[cmdrdata]

Hello all! 24 pages of the most informative forum I think I have ever read!

<Dadioh,CMDRdata>
My macbook has no power or boot.
I have working mag safe/board and battery
ISL6258A pin 14 measures .17 without battery/ .67 with battery
G3Hot .25 without battery/ 0-.97 with battery(starts at .97 and fades to 0)

Checked the voltage from magsafe to battery

I have attached a picture of what I found. I have read all 24 pages of the post and still am not sure how to proceed.

Any help is appreciated.
Thanks

G3HOT should ALWAYS be on and measures around 3.4v whenever magsafe or battery is plugged in. It is the heart of the system in that this voltage provider power to the SMC chip (U4900 H8S2117). Without G3HOT present, the system will never power on because all enabling signal to various system and other voltages that the system need will not be turned on. Find out why G3HOT is not on. It is not a high current voltage. This supply is spec'd to provide only about 250 mA max.

From your measurements, and I am curious about the 16.35v. Is the magsafe LED green? If so, I don't understand it as the SMC cannot possibly communicate with the magsafe if it doesn't have G3HOT.
Do you see 11-12v on the fuse above the battery connector (small white block), if you do, then perhaps the G3HOT you measured is not really G3HOT?

----------

I Give a battery to a friend yesterday and now it's fully charged.
I tried some tests:
1°) The test button with green light doesn't work, I was thinking that one light staid green but all are flashing 4 or 5 times and then nothing is staying green.

2°) I cannot start the MPB on battery but if I start it with the Magsafe and then remove the Magsafe it staid on the windows "DOS MENU WITH SAFE MODE" boot screen.

Well if someone has the clue .

Thanks.

Look for BIL in the schematic and you'll see that battery status in your MBP (unibody) is turned on via serial I2L lines (SDA/SCL). The SMC sends a digital pulse train to tell the LED indicators how many to turn on.
On the system state, if the MBP is past the POST state, then if the battery can provide 12v (as indicated by you measuring 12v with battery alone on the system fuse by the battery), the system will stay on once it thinks power comes from magsafe. Your problem is that the SMC doesn't know that the battery is available.
The DOS menu stuff is OS related, not hardware.

 

[mac-n-sauce]

G3HOT should ALWAYS be on and measures around 3.4v whenever magsafe or battery is plugged in. It is the heart of the system in that this voltage provider power to the SMC chip (U4900 H8S2117). Without G3HOT present, the system will never power on because all enabling signal to various system and other voltages that the system need will not be turned on. Find out why G3HOT is not on. It is not a high current voltage. This supply is spec'd to provide only about 250 mA max.

From your measurements, and I am curious about the 16.35v. Is the magsafe LED green? If so, I don't understand it as the SMC cannot possibly communicate with the magsafe if it doesn't have G3HOT.
Do you see 11-12v on the fuse above the battery connector (small white block), if you do, then perhaps the G3HOT you measured is not really G3HOT?

My magsafe does not light up at all. The battery indicator does not light at all. I actually get 12.47v on the white fuse. G3HOT is the two power on pads. Actually the lower one of the two. I have another working 2010 unibody and have checked measurements against it. My G3HOT measures .97v with magsafe plugged in and working fully charged battery plugged in.

 

[cmdrdata]

My G3HOT measures .97v with magsafe plugged in and working fully charged battery plugged in.

I assume you are referring to the bad MBP right? I don't see how a "GOOD" board would measure 0.97v for the G3HOT. If you look at the schematic, raw DCIN and battery power merged at the input of GeHOT regulator via a paired diode (look for PPDCIN_G3H_OR_PBUS in the schematic block diagram) which then goes through LT3470, a low voltage regulator that generate the 3.42v.

CLEVER APPLE ENGINEER: In the attached block diagram it looked like pair of "diodes" are real individual diodes. As it turned out, these are blocking diodes that are built in into the FETs Q7080 and Q7085 and would actually allow DC voltage and small amount of current from the battery to flow to the G3HOT regulator even when there is no Vgs (gate voltage that turns on the FET). The chip spec and A1278 schematic on p58 called this "body diode". So for G3HOT to turn on without magsafe, it has to flow through from BATT --> Q7055 --> R7050 --> L7030 --> Q7030 --> R7020 --> Q7085 --> G3HOT regulator. Ain't that clever. NOTE: in A1181 Macbook, the diodes mentioned are REAL diodes, not part of the FETs

 

[mac-n-sauce]

I assume you are referring to the bad MBP right? I don't see how a "GOOD" board would measure 0.97v for the G3HOT. If you look at the schematic, raw DCIN and battery power merged at the input of GeHOT regulator via a paired diode (look for PPDCIN_G3H_OR_PBUS in the schematic block diagram) which then goes through LT3470, a low voltage regulator that generate the 3.42v.

Yes on the bad board. Do you know where the LT3470 is located. I understand the voltage is wrong, I am just lost at how to trace it back to find the source of the problem.

 

[cmdrdata]

Yes on the bad board. Do you know where the LT3470 is located. I understand the voltage is wrong, I am just lost at how to trace it back to find the source of the problem.

A while back someone posted a board view" file for A1278 with an executable apps that ill run on a PC (I use Mac of course), and thus have not attempted to run that (even though I have Parallels installed with windows 7). I think that tool will give you component location. Sorry.

 

[mac-n-sauce]

A while back someone posted a board view" file for A1278 with an executable apps that ill run on a PC (I use Mac of course), and thus have not attempted to run that (even though I have Parallels installed with windows 7). I think that tool will give you component location. Sorry.

Yes, I saw it and am too on a mac

 

[DjErase]

G3HOT should ALWAYS be on and measures around 3.4v whenever magsafe or battery is plugged in. It is the heart of the system in that this voltage provider power to the SMC chip (U4900 H8S2117). Without G3HOT present, the system will never power on because all enabling signal to various system and other voltages that the system need will not be turned on. Find out why G3HOT is not on. It is not a high current voltage. This supply is spec'd to provide only about 250 mA max.

From your measurements, and I am curious about the 16.35v. Is the magsafe LED green? If so, I don't understand it as the SMC cannot possibly communicate with the magsafe if it doesn't have G3HOT.
Do you see 11-12v on the fuse above the battery connector (small white block), if you do, then perhaps the G3HOT you measured is not really G3HOT?

----------



Look for BIL in the schematic and you'll see that battery status in your MBP (unibody) is turned on via serial I2L lines (SDA/SCL). The SMC sends a digital pulse train to tell the LED indicators how many to turn on.
On the system state, if the MBP is past the POST state, then if the battery can provide 12v (as indicated by you measuring 12v with battery alone on the system fuse by the battery), the system will stay on once it thinks power comes from magsafe. Your problem is that the SMC doesn't know that the battery is available.
The DOS menu stuff is OS related, not hardware.

Thanks for all but how can I trace the SDA/SCL signal because I see it on the schematic pdf I downloaded but it is not so easy in real without oscilloscope?

 

[playwright]

deciphered solution

On a 2007 MacBook black, all up2date.

The discussion helped me better define problem w/mag orange-green-orange behavior issue.

Led me to http://support.apple.com/kb/HT3964

Yep, not sophisticated here, but solving problems.

Best,
playwright

 

[mac-n-sauce]

A while back someone posted a board view" file for A1278 with an executable apps that ill run on a PC (I use Mac of course), and thus have not attempted to run that (even though I have Parallels installed with windows 7). I think that tool will give you component location. Sorry.

I have looked back through this post and can not find the 2010 13" board view. Does anyone know what page it is on or can someone repost?

Thanks, kinda stuck until I can figure out what is restricting the G3HOT voltage.

 

[Dadioh]

On a 2007 MacBook black, all up2date.

The discussion helped me better define problem w/mag orange-green-orange behavior issue.

Led me to http://support.apple.com/kb/HT3964

Yep, not sophisticated here, but solving problems.

Best,
playwright

That is SMC reset instructions and, yes, that is the very first step anyone should take when troubleshooting. But it is good to have the link here. Thanks

----------

I have looked back through this post and can not find the 2010 13" board view. Does anyone know what page it is on or can someone repost?

Thanks, kinda stuck until I can figure out what is restricting the G3HOT voltage.

I don't know if there is a board view file for the 2010 that I have ever seen. I am interested too if someone has it.

 

[mac-n-sauce]

That is SMC reset instructions and, yes, that is the very first step anyone should take when troubleshooting. But it is good to have the link here. Thanks

----------



I don't know if there is a board view file for the 2010 that I have ever seen. I am interested too if someone has it.

Dadioh> any ideas on how I can figure out why I am getting .97v at the G3HOT and no magsafe led's

 

[jugger18]

I have had two dc-in boards be the point of failure. For no power boards, if you have a good spare dc in board, it is an easy place to start.

 

[Dadioh]

Dadioh> any ideas on how I can figure out why I am getting .97v at the G3HOT and no magsafe led's

It is a pretty basic power supply on the G3Hot so I would check the components around the supply to make sure the resistance measurements are OK with power removed from the board. I don't have access to the schematic at the moment but that is where you want to start. Have you located the G3Hot supply location on the board or is that where you are stuck at the moment?

----------

I have had two dc-in boards be the point of failure. For no power boards, if you have a good spare dc in board, it is an easy place to start.

Agreed. I usually have a few on hand because they are a common failure point. You can pick them up around $20 on eBay if you search. But make sure you get the correct one. For example the 2008 Macbook 13" non-Pro Aluminum unibody uses a different one than the 2009 Macbook Pro 13". The mounting screw locations are different. So just be careful to order the right one for your Macbook.

 

[jugger18]

It is a pretty basic power supply on the G3Hot so I would check the components around the supply to make sure the resistance measurements are OK with power removed from the board. I don't have access to the schematic at the moment but that is where you want to start. Have you located the G3Hot supply location on the board or is that where you are stuck at the moment?

----------



Agreed. I usually have a few on hand because they are a common failure point. You can pick them up around $20 on eBay if you search. But make sure you get the correct one. For example the 2008 Macbook 13" non-Pro Aluminum unibody uses a different one than the 2009 Macbook Pro 13". The mounting screw locations are different. So just be careful to order the right one for your Macbook.

Yep although if you are just having a spare for testing the model does not matter if testing outside the case...they have the same connector and power, just different physical board dimensions

 

[cmdrdata]

FET back diode behavior

I need to confirm my theory/description on how battery power can flow to the G3HOT regulator (see my edited post #583). So if any of you have a known good FET like HAT1128, can you test and see if 12v is measureable in SOURCE pin if you apply 12v to DRAIN with GATE grounded? I am also pretty sure of the reverse, i.e., if you apply 12v to the SOURCE pin, you will not see 12v on the DRAIN side. This test should be harmless and non-destructive to the device under test.

 

[mac-n-sauce]

I need to confirm my theory/description on how battery power can flow to the G3HOT regulator (see my edited post #583). So if any of you have a known good FET like HAT1128, can you test and see if 12v is measureable in SOURCE pin if you apply 12v to DRAIN with GATE grounded? I am also pretty sure of the reverse, i.e., if you apply 12v to the SOURCE pin, you will not see 12v on the DRAIN side. This test should be harmless and non-destructive to the device under test.

I have several good 13" and 15" laptops, so I will test them, but I am new to all this and do not know where the items are located. If you have a picture that would be greatly appreciated.

 

[mac-n-sauce]

It is a pretty basic power supply on the G3Hot so I would check the components around the supply to make sure the resistance measurements are OK with power removed from the board. I don't have access to the schematic at the moment but that is where you want to start. Have you located the G3Hot supply location on the board or is that where you are stuck at the moment?

----------

I know where the power on pads are but I do not know where the LT3470 chip is to check resistance.

 

[rickAC]

Aple's name for LT347 is U990. I have board view file for MBP A1286 (Late 2008-Early 2009). Hopefully it is located at same place in yours.

 

[mac-n-sauce]

Aple's name for LT347 is U990. I have board view file for MBP A1286 (Late 2008-Early 2009). Hopefully it is located at same place in yours.

View attachment 345840

Where did you get your board view from?

 

[U-234]

Smbus_smc_bsa_sda == 1.990v

Dadioh/cmdrdata - I have Early Macbook Pro 13 with liquid spill, after detailed cleanup everything works except charging the battery (solid green) I tried all the SMC resets and stuff like this. Next went to component level and started capturing my measurements. I looked at the whole charging circuit from the battery connection, on the U7000 ==> SMC_BC_ACOK i'm getting 3.4V like i'm supposed to. FETS 7035&7030 D-S getting 12V, the only interesting thing is that i'm only getting 1.990V instead of 3.4 on pin 6 (SMBUS_SMC_BSA_SDA) on the battery connector. I checked all my 3 other identical boards and they all have 3.4V with battery connected(they all are charging battery no problem). So this to me is the culprit the question is what is causing the lower voltage here...

Thanks