SMC Issue on MBP 13 - Hardware Troubleshooting Guide

[pw777]

dead A1278

Hi,

I am new to this forum and I am impressed by the level of detail of this thread and the amount of information given. Now I have a question myself.

I have an A1278 13" unibody MBP that won't boot. These are the symptoms and results of measurements according to what others have written in this thread:

• battery is charging (green led turns to amber on magsafe connector); battery was charged a few days ago (green led) and now again needs charging so it is being depleted when macbook is left untouched; battery voltage is 12,33V and increasing

• G3hot voltage 3,409V, bridging G3hot has no effect

• 
  there are pulses on battery connector pin 4 every second between 3,402V and 0V lasting for 20 to 25 msec (with or without power connected). That would be the SDA line to the battery if I'm not mistaken

• 12,33V on many electrolytic capacitors and 16,79V on some electrolytic capacitors when power connected (drops to battery voltage when power disconnected)

• 
  the temporary bypass described in the first post does not work

• no visible corrosion, no water spills

• white smd fuse near battery connector and near DC board are ok; green low value resistors are ok

• apparently someone has already tried to bridge G3hot (traces visisble of a screwdriver or another tool) but also on the reverse side: see photograph below (red circled contacts). I don't have the schematics for this machine so I cannot tell what the purpose of these contacts is. I know that the previous owner has brought it to an Apple service centre but did not want to spend the money to have it repaired. Probably the repair center has bridged these contacts.

Does anybody have any suggestion of what to try next?

Thanks
Patrick

 

[Dadioh]

Hi,

I am new to this forum and I am impressed by the level of detail of this thread and the amount of information given. Now I have a question myself.

I have an A1278 13" unibody MBP that won't boot. These are the symptoms and results of measurements according to what others have written in this thread:

• battery is charging (green led turns to amber on magsafe connector); battery was charged a few days ago (green led) and now again needs charging so it is being depleted when macbook is left untouched; battery voltage is 12,33V and increasing

• G3hot voltage 3,409V, bridging G3hot has no effect

• 
  there are pulses on battery connector pin 4 every second between 3,402V and 0V lasting for 20 to 25 msec (with or without power connected). That would be the SDA line to the battery if I'm not mistaken

• 12,33V on many electrolytic capacitors and 16,79V on some electrolytic capacitors when power connected (drops to battery voltage when power disconnected)

• 
  the temporary bypass described in the first post does not work

• no visible corrosion, no water spills

• white smd fuse near battery connector and near DC board are ok; green low value resistors are ok

• apparently someone has already tried to bridge G3hot (traces visisble of a screwdriver or another tool) but also on the reverse side: see photograph below (red circled contacts). I don't have the schematics for this machine so I cannot tell what the purpose of these contacts is. I know that the previous owner has brought it to an Apple service centre but did not want to spend the money to have it repaired. Probably the repair center has bridged these contacts.

Does anybody have any suggestion of what to try next?

Thanks
Patrick

The picture is definitely the G3Hot supply but I have never used the pads you identified so maybe there is a trick I don't know about. My first suggestion would have been to try starting it by shorting the start pins on the logic board but it looks like ey were trying that already. The reson being, if the power switch is bad then you would not be able to start with the power switch. Another thought... If the power switch is bad then you would not be able to do the smc bypass. But you can do it using the pads on the logic board. It is very tricky to keep them shorted while connecting power. I use very fine tweezers but it is hit and miss. You could try soldering fine wires to the pads to make it easier.

If smc bypass still doesn't work you have a tough troubleshooting road ahead of you. If the smc itself is bad then you may be done.

If you can enable pm or email I can send you some tips.

 

[pw777]

I soldered two fine wires to the pads and then tried the SMC bypass by shorting these wires. But it makes no difference whether I try it with the power button or the pads: no success. W.r.t. the SMC bypass: the first post does not mention whether this should be tried with the battery connected or disconnected (I tried both). No luck.

I am inclined to think that the SMC still works (at least partially) because the battery gets charged and there are pulses on the SDA and SCL lines.

How can I check that the system correctly detects an opened display lid?

I enabled email (I think), have not found how to enable PM.

Thanks
Patrick

 

[Dadioh]

I soldered two fine wires to the pads and then tried the SMC bypass by shorting these wires. But it makes no difference whether I try it with the power button or the pads: no success. W.r.t. the SMC bypass: the first post does not mention whether this should be tried with the battery connected or disconnected (I tried both). No luck.

I am inclined to think that the SMC still works (at least partially) because the battery gets charged and there are pulses on the SDA and SCL lines.

How can I check that the system correctly detects an opened display lid?

I enabled email (I think), have not found how to enable PM.

Thanks
Patrick

One of the signals that think would really help us out is ALL_SYS_PWRGD. This feeds one of the inputs to U2850 (AND gate) and would be a good first step to tell if all of the power supplies are coming up OK. The AND gate is a TC7SZ08AFEAPE and is a SOT665 package. If someone locates it before I do then post a picture for the benefit of us all.

I have had boards that would do an SMC bypass OK but not chime. Fan spinning and power to the CPU and Northbridge. However, one or more bad power supplies. Maybe the ALL_SYS_PWRGD is a good starting point in these cases.

 

[cmdrdata]

I have had boards that would do an SMC bypass OK but not chime. Fan spinning and power to the CPU and Northbridge. However, one or more bad power supplies. Maybe the ALL_SYS_PWRGD is a good starting point in these cases.

I have been googling for POST (power on self test) for our laptop and have come up empty when it comes to detailed info. What I am thinking is that there is a process going when the SMC is up (by virtue of the G3HOT is good) and thus when it received "power on" signal it reads a ROM/PROM and perform a quick hardware tests. Along the way it failed to get a correct status from one or more of the device being tested thus the NO-CHIME" condition. So which device or component failed? Knowing this would help trouble shoot systems with your symptom. Anyone has this info? I know one of this is the SODIMM presence test.

I was just looking at the power block diagram and it struck me: there are two low voltage source called PP3V42_something and PP3V3_something. That's a minor difference in voltage but it seemed that 3.42v (aka G3HOT) is on all the time when battery or magsafe is connected, whereas the 3.3v is probably only on when the SMC deemed everything is OK (3.3v derived from 5v DC regulator). I also noticed that some SCL/SDA lines read by the MCP/CPU is pulled up via the 3.3v source. Worth checking!

 

[peislander]

One of the signals that think would really help us out is ALL_SYS_PWRGD. This feeds one of the inputs to U2850 (AND gate) and would be a good first step to tell if all of the power supplies are coming up OK. The AND gate is a TC7SZ08AFEAPE and is a SOT665 package. If someone locates it before I do then post a picture for the benefit of us all.

I have had boards that would do an SMC bypass OK but not chime. Fan spinning and power to the CPU and Northbridge. However, one or more bad power supplies. Maybe the ALL_SYS_PWRGD is a good starting point in these cases.

I got a picture of the u2850 for the late 2008 15 inch unibody.Its marked R2 & is to the right of the screw.
I think on the 13 inch aluminum unibody & Mid 2009 13 inch Pro The u2850 is just down & to the left of u6915.Papabear had marked a few components on the pic.The only reason I believe its there is because q3840(SI2312BDS) is beside it on all boards.I don't want to post a pick till someone can confirm.Hope this helps

 

[peislander]

free mobo downloads

One of the signals that think would really help us out is ALL_SYS_PWRGD. This feeds one of the inputs to U2850 (AND gate) and would be a good first step to tell if all of the power supplies are coming up OK. The AND gate is a TC7SZ08AFEAPE and is a SOT665 package. If someone locates it before I do then post a picture for the benefit of us all.

I have had boards that would do an SMC bypass OK but not chime. Fan spinning and power to the CPU and Northbridge. However, one or more bad power supplies. Maybe the ALL_SYS_PWRGD is a good starting point in these cases.

I just googled tc7sz08afeape & found some free motherboard schematics downloads.Some for the late 13 inch 2008 aluminum unibody m97 & m97a & one for the a1342 white unibody k84.Cheers & Happy New Year

 

[cmdrdata]

I just googled tc7sz08afeape & found some free motherboard schematics downloads.Some for the late 13 inch 2008 aluminum unibody m97 & m97a & one for the a1342 white unibody k84.Cheers & Happy New Year

Peislander, good detective work and thanks for sharing. That one website with all chinese letters with keyword M97A looked great. There is a bunch of PDF icons that possibly be for other schematics with chinese prices (Y for yuan, chinese currency, I think). Happy New Year everyone.

 

[adalbert123]

Hello and HNY to everyone. I'm very impressed with pro level of this forum. I also have a battery related problem.
1) Macbook unibody white 2,26 with original config (RAM 2 GB, HDD etc.)
2) Doesn't charge the battery, mac os shows an "X" and info that there is no battery; same info in machine details on about this mac
3) the camera - isight doesn't work either
4) everything else works perfect - macbook boots to mac os on magsafe; disconnecting it results in power down - the battery wouldn't pick up
5) the magsafe is either always green or orange for a short while and then stable constant green
6) tried other magsafe - the same effect
7) tried to try other battery but sth I had might have beenfaulty - but the same result
8) reconnected all plugs and put it back - all the same
There was no liquid spill or other damage I might know of.
One day just got it like this
Regards
W

 

[cmdrdata]

Hello and HNY to everyone. I'm very impressed with pro level of this forum. I also have a battery related problem.
1) Macbook unibody white 2,26 with original config (RAM 2 GB, HDD etc.)
2) Doesn't charge the battery, mac os shows an "X" and info that there is no battery; same info in machine details on about this mac
3) the camera - isight doesn't work either
4) everything else works perfect - macbook boots to mac os on magsafe; disconnecting it results in power down - the battery wouldn't pick up
5) the magsafe is either always green or orange for a short while and then stable constant green
6) tried other magsafe - the same effect
7) tried to try other battery but sth I had might have beenfaulty - but the same result
8) reconnected all plugs and put it back - all the same
There was no liquid spill or other damage I might know of.
One day just got it like this
Regards
W

Before doing anything else that might cause serious damage, get a KNOWN good battery. What you have is a classic symptom of bad battery (in shutdown mode) and thus no longer communicating with the SMC/CPU. On your iSight problem, check out this article: http://www.smallroomsoftware.com/articles/2007/5/9/broken-macbook-isight-fixed

 

[adalbert123]

Appreciate quick response. I'll (1) follow the isight guide (2) get the new battery (3) let you know what came out of that
Regards
W

 

[peislander]

Peislander, good detective work and thanks for sharing. That one website with all chinese letters with keyword M97A looked great. There is a bunch of PDF icons that possibly be for other schematics with chinese prices (Y for yuan, chinese currency, I think). Happy New Year everyone.

Yes just went to that site again with Google chrome to translate & found more schematics.Apple 15 inch 1287 k19,Apple 13 inch 1181 k36C,Apple 15 inch M98... ETC.Still can't find any board viewer files.Later

 

[Papabear2]

I got a picture of the u2850 for the late 2008 15 inch unibody.Its marked R2 & is to the right of the screw.
I think on the 13 inch aluminum unibody & Mid 2009 13 inch Pro The u2850 is just down & to the left of u6915.Papabear had marked a few components on the pic.The only reason I believe its there is because q3840(SI2312BDS) is beside it on all boards.I don't want to post a pick till someone can confirm.Hope this helps

I'm BACK!! Sorry it took me so long to respond but a crashed HDD and problems with the account meant I lost patience and just decided to re-register as Papabear2 !

Here is the picture I promised which shows the location of the two 1k ohm resistor pull ups for SMC Battery A (Yellow arrow)
I also believe Peislander is correct that U2850 is also on the picture (Red arrow) as it does have R2 designation and a 0 ohm resistor as per the schematic?.

This picture is from a 2009 macbook a1278.

I love where this thread is going next as it would be interesting to understand the process after power good to chime and I think cmdrdata is on the right tracks that there is some check of vital components.

Page 64 of the schematic shows Power control table which seems to check power conditions of CPU , Video, Memory etc are good before suppling "All_sys_pwrgd" to SMC that Dadioh suggested could be key?
All this centers around U7859 another 5pin package "R2" type as above so it might be worthwhile locating that as it appears from the table that the Run (S0) condition, or Sleep (S3) condition, Soft off (S5) or Battery off (G3Hot) condition can be read from this device and may give us a clue as to what condition it thinks it is in?
I'll come back if I can find it with another picture

 

[peislander]

Peislander, good detective work and thanks for sharing. That one website with all chinese letters with keyword M97A looked great. There is a bunch of PDF icons that possibly be for other schematics with chinese prices (Y for yuan, chinese currency, I think). Happy New Year everyone.

I'm BACK!! Sorry it took me so long to respond but a crashed HDD and problems with the account meant I lost patience and just decided to re-register as Papabear2 !

Here is the picture I promised which shows the location of the two 1k ohm resistor pull ups for SMC Battery A (Yellow arrow)
I also believe Peislander is correct that U2850 is also on the picture (Red arrow) as it does have R2 designation and a 0 ohm resistor as per the schematic?.

This picture is from a 2009 macbook a1278.

I love where this thread is going next as it would be interesting to understand the process after power good to chime and I think cmdrdata is on the right tracks that there is some check of vital components.

Page 64 of the schematic shows Power control table which seems to check power conditions of CPU , Video, Memory etc are good before suppling "All_sys_pwrgd" to SMC that Dadioh suggested could be key?
All this centers around U7859 another 5pin package "R2" type as above so it might be worthwhile locating that as it appears from the table that the Run (S0) condition, or Sleep (S3) condition, Soft off (S5) or Battery off (G3Hot) condition can be read from this device and may give us a clue as to what condition it thinks it is in?
I'll come back if I can find it with another picture

Good to see your back.Thanks for posting a pick of the resistors.Bummer but all my resistors checked out so back on the shelf.

What chip is the voltage comparator?You talked about it in an earlier post but I can't seem to find what or where it is.Thanks

 

[Papabear2]

Good to see your back.Thanks for posting a pick of the resistors.Bummer but all my resistors checked out so back on the shelf.

What chip is the voltage comparator?You talked about it in an earlier post but I can't seem to find what or where it is.Thanks

Are you talking about the one in the "1-wire overvoltage protection" circuit I kept blowing??
If so it is marked LM397 and it is the 5pin package immediately top right of the LVDS connector in the picture I posted yesterday. This is the only component in that circuit to the right of the connector as all the other components are above and to the left of it.
Happy hunting

 

[peislander]

Are you talking about the one in the "1-wire overvoltage protection" circuit I kept blowing??
If so it is marked LM397 and it is the 5pin package immediately top right of the LVDS connector in the picture I posted yesterday. This is the only component in that circuit to the right of the connector as all the other components are above and to the left of it.
Happy hunting

Yes I guess that's it,I must have missed the post where it was called voltage comparator.I was just calling it u6915.I can find it on the a1278 13 inch unibody.On the 15 inch its on the cpu side just up from dc in connector.Do you know where it is on the 13 inch MBP mid 09?Would it be down from the lcd connector & marked PHMI on top? Or maybe to the left & marked T11G?Thanks

 

[saisworld]

Macbook (early 2008) wont turn on

Hello ,

Saw this thread which got lots of information regarding macbook pro / unibody not turning on. Just wondering if anyone will be able to suggest reg my macbook(early 2008) , all of a sudden it stopped working, am unable to turn on. Tried SMC reset, nothing works. finally I took laptop to apple and they said I need to replace my logicboard which would cost me around £300 + labour + tax. I came back not sure what to do, cant spend £300++ on getting new logic board. Also am not sure if it will work after replacing logic board.

From what I read in this post, is check for that G3Hot to see if its 3.4V, am very poor on electronics could some suggest how can I do that?

Any help in getting this up to speed is really appreciated.

Thanks in advance
Xai

 

[macattack600]

Question about rail and ground

What a enormous amount of wealth of info on this board! I had a question about a regular macbook which I guess would appt to the MB pro too. I had a logic board that would glow orange with no battery and cut itself on and then off and keep doing it (liquid spilled) A computer tech once told me that he thought the short was in it between the PPBus_3GH (3 volt hot) rail and ground which was the main source for power for the components in the board is there any detailed picture of this exact area for any logic board some may have I'm working on getting some shots of this a1181 MBL but even off a say a1278 or something would work too. Thanks.

 

[cmdrdata]

What a enormous amount of wealth of info on this board! I had a question about a regular macbook which I guess would appt to the MB pro too. I had a logic board that would glow orange with no battery and cut itself on and then off and keep doing it (liquid spilled) A computer tech once told me that he thought the short was in it between the PPBus_3GH (3 volt hot) rail and ground which was the main source for power for the components in the board is there any detailed picture of this exact area for any logic board some may have I'm working on getting some shots of this a1181 MBL but even off a say a1278 or something would work too. Thanks.

First of all, logic board should not glow at all, so I think the glowing component is probably the shorted device. It glows because instead of normal impedance, it is probably defective and because it is not a fully shorted condition (0 ohm) it has some resistance value that is low but not enough to trigger power supply overcurrent circuit that would cut off power immediately. Remove it and see if the logic board still have overheat problem. I don't believe there is a power rail called PPBUS_3GH. There is the main supply rail (from adapter or battery that is the "load" side of either supply called PPBUS_G3H, and it is nominally 12v. This supply can provide up to 8 amps or so, and the logic board taps of this line to generate various system powers like 3,3v, 5v, 1.Xv, etc.

 

[macbooksaver]

1

 

[macbooksaver]

short ac adapter

hi dadioh, have you ever across one that after the power is press the green led on the charger go off?

 

[Dadioh]

hi dadioh, have you ever across one that after the power is press the green led on the charger go off?

I have not seen this behaviour before. So you are saying the green light on the magsafe is on... then you press the power button and it goes off? Then when you release the power button does it come back on?

The power button, when pushed, grounds pin 5 of the keyboard connector, which is connected through a 1K resistor to the signal SMC_ONOFF_L which goes to the SMC. It should not carry much current. The green LED on the magsafe is controlled by the SMC. There is an output (pin 14) from the charger device on the logic board that tells the SMC that the charger circuit is OK. The SMC then asserts the green LED.

Not sure if that helps you troubleshoot. But to answer your question I have not seen that behaviour before.

 

[macbooksaver]

Thanks for the tip dadioh, i read a lot of your add and i see you have a lot of experience with these particular unibody, especially down to component level, in the feature i will bother you with question if you don't might

 

[imDave]

Looking for info on part that melted

Hi
I have a MB 13 Uni A1278 which I'm trying to rescue, new glass battery etc. Replaced the battery non Apple, it wouldn't charge (no orange light). Tried old batt again went into charge just fine. Put new batt in again and left it about 5 min this time waiting for orange light, then I started smelling burning component, pulled pwr, started looking. Under logic card next to battery connector is a melted component. Looks like it might have been a resistor. It definitely connects to the 1st 3 pins on the battery cable connector other end ??? Has .18 volts on opposite end from batt conn and 0 volts on batt conn end when pwr is on. MB still works JUST won't charge anymore. This part is in between the batt cable conn and the memory socket. Anybody have any clues what this parts value might be and if it's a resistor, only a glob left. Also any hints on why a shorted?? battery caused the charger circuit to melt?

Thanks,
Dave

 

[Dadioh]

Hi
I have a MB 13 Uni A1278 which I'm trying to rescue, new glass battery etc. Replaced the battery non Apple, it wouldn't charge (no orange light). Tried old batt again went into charge just fine. Put new batt in again and left it about 5 min this time waiting for orange light, then I started smelling burning component, pulled pwr, started looking. Under logic card next to battery connector is a melted component. Looks like it might have been a resistor. It definitely connects to the 1st 3 pins on the battery cable connector other end ??? Has .18 volts on opposite end from batt conn and 0 volts on batt conn end when pwr is on. MB still works JUST won't charge anymore. This part is in between the batt cable conn and the memory socket. Anybody have any clues what this parts value might be and if it's a resistor, only a glob left. Also any hints on why a shorted?? battery caused the charger circuit to melt?

Thanks,
Dave

Hi Dave. Can you post a picture and I can help you out.