SMC Issue on MBP 13 - Hardware Troubleshooting Guide

[mac-n-sauce]

I have already searched for the lt3470, but the results are more then one. Witch one is the right?

Thank you, once again.

Search for "LT3470A"

Second one that comes up.
I bet your diode is not bad!

 

[Musicsoul78]

Update

Hey, why give up so easy that IC chip is $6 and pretty easy to replace!

that ic chip required a heatflow station and i dont have those!!

Anyway because you guys helped me so much i have now been promoted in my job and due to your extended knowledge i have had many macs ripped apart and diagnosed faults using this thread. Top Class

now i have a A1278 , corrosive damage, cracked lcd, and burnt out magsafe board.....

Cleaned corrrosion, replace magsafe, replaced screen, but power button will not power board so i did gehot pin 5-6 switch and booted fine. but keyboard is dead touch pad is good. what do i replace now????

Is it the key board or power button or both?

ps will macbook a1342 lcd fit macbook a a1287?

 

[Dadioh]

that ic chip required a heatflow station and i dont have those!!

Anyway because you guys helped me so much i have now been promoted in my job and due to your extended knowledge i have had many macs ripped apart and diagnosed faults using this thread. Top Class

now i have a A1278 , corrosive damage, cracked lcd, and burnt out magsafe board.....

Cleaned corrrosion, replace magsafe, replaced screen, but power button will not power board so i did gehot pin 5-6 switch and booted fine. but keyboard is dead touch pad is good. what do i replace now????

Is it the key board or power button or both?

ps will macbook a1342 lcd fit macbook a a1287?

Keyboard and power switch are all in one. You have to replace the keyboard. Not uncommon in liquid spills.

 

[Musicsoul78]

Keyboard and power switch are all in one. You have to replace the keyboard. Not uncommon in liquid spills.

thanks dadioh im on it!!

 

[mac-n-sauce]

thanks dadioh im on it!!

Unibody to non unibody lcds are not the same.

----------

that ic chip required a heatflow station and i dont have those!!

Anyway because you guys helped me so much i have now been promoted in my job and due to your extended knowledge i have had many macs ripped apart and diagnosed faults using this thread. Top Class

now i have a A1278 , corrosive damage, cracked lcd, and burnt out magsafe board.....

Cleaned corrrosion, replace magsafe, replaced screen, but power button will not power board so i did gehot pin 5-6 switch and booted fine. but keyboard is dead touch pad is good. what do i replace now????

Is it the key board or power button or both?

ps will macbook a1342 lcd fit macbook a a1287?

You can get a hot air station for $60(us) from china on ebay. Great little machine.
Search:
AT858D+ Hot Air Solder Blower SMD Rework Station 220V&110V WEP Heat Gun

 

[davyjcrow]

MBP Late 2008 powering issues

Hi,

Reading this thread with great interest. I have a MBP which will intermittently not power on and was wondering if someone can help diagnose what component could be to blame. This is my last resort before replacing the board.

One of three things happen
- When power button pressed, sleep light flashes once (1/4 sec), fans spin for 1/4 sec and then system goes dead, no video activity, no chimes
- System boots to grey screen but at the point when the OS starts, the screen flashes white for a fraction of a second and then system abruptly powers off
- System powers itself off immediately when lid is opened to wake from sleep, with screen flash as above

Alternatively the system will sometimes boot and wake from sleep without any issues whatsoever. There seems to be a pattern where the system requires a "recovery" period following a failed boot - if you try again immediately it won't work, whereas if you leave it for a while it then stands a better chance of powering on. This might be a co-incidence however.

Have tried usual remedies (PRAM, SMC reset) and actually sent the logic board to a tech for repair. I think he reflowed the solder, it appeared to solve the issue for a week or so but then the problem relapsed. As I say the issues are all intermittent.

I have some electronics knowledge and can work with SMT parts although not BGAs. Any help is much appreciated!

 

[U-234]

PBus Voltage Sensor reading below the lower range

LB Early 2011 i5 13', the AHT reveals issue with one of the voltage sensors with the reading 0.592 V which is below the lower range.

Dadioh/cmdrdata or anybody with the deeper knowledge on this issue - i'm trying locate where is that sensor on my LB. Replacing it or getting the part is not an issue.

I was trying to figure out and looked into Voltage & Load side current sensing, I replaced Q5300 both N-channel and P-channel fet which had burned legs and wrong voltage (below 12V) after replacing it i'm getting now 12V but AHT still shows the Pbus voltage rail below the range.

So where is that damn sensor? Any insight would be appriciated.

Reading below the lower range

Sensor
location: VPOR
type: Voltage
Low-Limit: 8.4V
high-limit: 12.75 V
description: P-Bus voltage
reading: 0.592 V

 

[mac-n-sauce]

LB Early 2011 i5, the AHT reveals issue with one of the voltage sensors with the reading 0.592 V which is below the lower range.

Dadioh/cmdrdata or anybody with the deeper knowledge on this issue - i'm trying locate where is that sensor on my LB. Replacing it or getting the part is not an issue.

I was trying to figure out and looked into Voltage & Load side current sensing, I replaced Q5300 both N-channel and P-channel fet which had burned legs and wrong voltage (below 12V) after replacing it i'm getting now 12V but AHT still shows the Pbus voltage rail below the range.

So where is that damn sensor? Any insight would be appriciated.

Reading below the lower range

Sensor
location: VPOR
type: Voltage
Low-Limit: 8.4V
high-limit: 12.75 V
description: P-Bus voltage
reading: 0.592 V

Is this the 15" or 13"

 

[U-234]

Is this the 15" or 13"

That would be 13' forgot to add it.

 

[mac-n-sauce]

That would be 13' forgot to add it.

Took me a minute but i figured it out from the Q5300.

 

[jdetmold]

Help?

Hey guys!
thanks for posting all this great information here! im hoping someone might be able to lead me in the right direction to fixing my macbook.

I have a 13" macbook unibody (not sure of the year) core 2 duo 2.4. it has never had any water damage or exposure to a surge that i know of (i have owned it since new)

working on it one day i noticed the green power adapter light was off and that it said not charging but it was still running fine off teh battery and continued to run till the battery died. after looking closer i noticed the light on the adapter was on just very very dim and could only be seen if i cuped my hands over it. now the computer will not power on at all smc reset has no effect booting with the keyboard disconnect from page 1 has no effect.

I have checked the dcin board and it seems to be functioning fine (gnd, 18v, sns, 18v, gnd), I checked the fuse on the front of the mb and it is good.
i do read 18v at this point as seen in the image i got from another post
Image

I have inspected teh board and unless i am missing something i see no physical damage to any components

If anyone can give me some idea as to what could be the cause or anything tI should test I would be most grateful!

 

[U-234]

Took me a minute but i figured it out from the Q5300.

I attached 3 pages of Voltage and PBus schematics.

Post #907

 

[cmdrdata]

Is this the 15" or 13"

PBUS is kinda generic. From the block diagram you attached (#907), it seemed that The Charger IC is also called the PBUS, the output of this device via the switching power FETs is 12v nominal that charges the battery as well as going through the fuse to power the system bus. So since you were able to get AHT (Apple Hardware Test) to run, I have to assume that 12v is actually available, thus I'd look first at R5400 (section 5D) and the chip that reports the voltage U7600 ISL95870, R7640 for the voltage sensed, and the logic signal that says power is good from that chip.

 

[Mirnes]

Took me a minute but i figured it out from the Q5300.

Mac n sauce can u pm me or email me?? Mirnes1979@gmail.com

 

[Dadioh]

I have checked the dcin board and it seems to be functioning fine (gnd, 18v, sns, 18v, gnd), I checked the fuse on the front of the mb and it is good.
i do read 18v at this point as seen in the image i got from another post
Image

I have inspected teh board and unless i am missing something i see no physical damage to any components

If anyone can give me some idea as to what could be the cause or anything tI should test I would be most grateful!

What voltage do you see on the middle sense pin on the magsafe? "Carefully" measure the center pin on the DC-in board so you don't short it to the adjacent pins. If it is working it should be around 3.4V.

 

[cmdrdata]

Hey guys!
thanks for posting all this great information here! im hoping someone might be able to lead me in the right direction to fixing my macbook.

I have a 13" macbook unibody (not sure of the year) core 2 duo 2.4. it has never had any water damage or exposure to a surge that i know of (i have owned it since new)

working on it one day i noticed the green power adapter light was off and that it said not charging but it was still running fine off teh battery and continued to run till the battery died. after looking closer i noticed the light on the adapter was on just very very dim and could only be seen if i cuped my hands over it. now the computer will not power on at all smc reset has no effect booting with the keyboard disconnect from page 1 has no effect.

I have checked the dcin board and it seems to be functioning fine (gnd, 18v, sns, 18v, gnd), I checked the fuse on the front of the mb and it is good.
i do read 18v at this point as seen in the image i got from another post
Image

I have inspected teh board and unless i am missing something i see no physical damage to any components

If anyone can give me some idea as to what could be the cause or anything tI should test I would be most grateful!

If I am in your position I'd try to ensure that all the magsafe pins are clean on BOTH the plug and socket sides. Then I'd find/borrow a known good magsafe adapter and try that as my initial troubleshooting methods. From your description, since you're not getting bright green or orange LED on the magsafe, I believe your system is not fully detecting the magsafe and since the battery is depleted, you then have a no start condition.

 

[Dadioh]

If I am in your position I'd try to ensure that all the magsafe pins are clean on BOTH the plug and socket sides. Then I'd find/borrow a known good magsafe adapter and try that as my initial troubleshooting methods. From your description, since you're not getting bright green or orange LED on the magsafe, I believe your system is not fully detecting the magsafe and since the battery is depleted, you then have a no start condition.

Very good point. I have seen more than a few MagSafe connectors where the springs on the pins are sticking and they stay retracted. Always check the MagSafe connector before proceeding to internal diagnostics.

 

[Musicsoul78]

You can get a hot air station for $60(us) from china on ebay. Great little machine.
Search:
AT858D+ Hot Air Solder Blower SMD Rework Station 220V&110V WEP Heat Gun[/QUOTE]

Thanks man i like it !!!!

----------



NEW ISSUE


macbook pro 13 2009 mid
MB990LL/A Model No: A1278 (EMC 2326*)

changed the display and all was fine apart from wifi so took display apart again and went to investigate could not see any damage to wifi board so put back 2 gather again and i have no back light ... (forgot to unplug battery the 2nd time i went in)

ps mac does work with external display

dadioh i do believe this is your field of expertise can you help at all buddy?

@dadioh
wow just read your backlight thread

holy sh@t balls you had lots of ****s giving you such hassle when you first started!!

Me and so many others on this forum are so glad you persevered thank you man ...

This is what i found
FUSE, 0402, V FAST ACTING, 2A
Voltage Rating V DC:32V
Fuse Current:2A
Breaking Capacity:35A @ 32V DC
Fuse Size Code:402

replace it on board pics you posted

if still dont work then its Wled can you confirm?

Many thanks

 

[U-234]

PBUS is kinda generic. From the block diagram you attached (#907), it seemed that The Charger IC is also called the PBUS, the output of this device via the switching power FETs is 12v nominal that charges the battery as well as going through the fuse to power the system bus. So since you were able to get AHT (Apple Hardware Test) to run, I have to assume that 12v is actually available, thus I'd look first at R5400 (section 5D) and the chip that reports the voltage U7600 ISL95870, R7640 for the voltage sensed, and the logic signal that says power is good from that chip.

I agree based on my AHT error PBus rail voltage below limit I was looking at all the pages with PBus. Two of them I already attached. On the Power Block Diagram I checked the voltage like you sugested. R5400 - 12V, ISL95870 - 1.05V and R7640 - 1.05V. So it appears the voltage is fine here.

I did the test on other working LB and the AHT revealed 12V on the VPOR sensor where on my other LB with the VPOR sensor issue it measured 0.5V. So where is the VPOR sensor getting that value from? Only 0.5V where I should be getting 12V.

Other PBus section is on page 49 (Voltage & Load side current sensing) 7D which refers to Q5300 - to me that sounded more like a sensor. It had few burned legs so I replaced it with a new one. However, that appeared not to make any effect on my 0.5V below limit voltage.

 

[Mori3000]

Here are a few quick checks.

Down near the battery connection there is a white bodied component that is the fuse that protects the main 12V supply to the board. If you (carefully) measure the voltage on both ends of the fuse then you should see a little over 12V. If not, check that fuse.

If you do not have power at the input to that fuse then the other fuse is on the underside of the board near the magsafe. That is the main fuse on the 18.5V input from the magsafe.

If that fuse doesn't have 18.5V at its input then you probably have a bad magsafe board. Give it a visual inspection for damage.

I have about the same board now, i have a logicboard a1278.
It was working but it was very slow, I thought that it must be becouse it has liquid damaged, i cleaned it up carefully yesterday and try to reinstall the windows with new Ram and hard drive, but it was still slow until i turn off the MBP before the installation finnish.

Today the MBP donot start at all and the mega safe not show any thing. I have 16.5v on the main fuse close to the DCin but i receive no voltage on the second fuse close to the battery. i receive no V onnon side of the fuse.

I replace the fuse but still the same. what could has happend!!???

By the way G3hot have only 1.2v?

thanks for all help.

 

[cmdrdata]

Today the MBP donot start at all and the mega safe not show any thing. I have 16.5v on the main fuse close to the DCin but i receive no voltage on the second fuse close to the battery. i receive no V onnon side of the fuse.

I replace the fuse but still the same. what could has happend!!???

By the way G3hot have only 1.2v?

thanks for all help.

no G3HOT = no start. The system depends on G3HOT to power the SMC, even if 12v is available on the second fuse by the battery. So that's the area you have to first resolve.

The fact that you have the system working at all, even if it is slow, means that somehow you have a deteriorating G3HOT circuit and possible a resistor that changed value due to previous issue, i.e., that liquid spill may have corroded/affected resistor or other components over time. L Rossmann mentioned about how to clean it and NOT to power it on until then.I would do that before going any further to prevent other damage.

 

[rickAC]

Hello,

I have a A1278, Unibody mbp 13" that will not power up. The problem seems to be in charging circuit - IC U7000. There is no 12,5V voltage output on PPBUS_G3H.
Please see the image attached.
I tried to isolate the problem but nothing seems to help. If someone have a good board please will you send a measurements of voltages.

 

[mac-n-sauce]

Hello,

I have a A1278, Unibody mbp 13" that will not power up. The problem seems to be in charging circuit - IC U7000. There is no 12,5V voltage output on PPBUS_G3H.
Please see the image attached.
I tried to isolate the problem but nothing seems to help. If someone have a good board please will you send a measurements of voltages.
View attachment 364791

1=16.7v 16=4.82v
2=16.7v 17-18=12.6v
3=4v 19-20=5v
4=3.2v 21=.62v
5=1.3v 23=12.6v
7=1v 24=13.4v
8=2.05v 25=16.97
10-12=3.4v 27-28=16.62v
14=3.2v

All other pins are ground
I could not find the U7060 if you tell me where it is I can give you those.

Q7000 pins 1-3 are 16.5v
pin 4 = 6.45v
pin 5 = 16.5-17v

Q7001 is the same as Q7000 except pin 4 = 16.5v

 

[rickAC]

Thanks mac.

What do and other think the problem is? Could it be U7000? In some of mb and mbplogic boards I had it was mostly Phase and UGate that was shorted to ground but this one is ok. No short around IC.

 

[mac-n-sauce]

Thanks mac.

What do and other think the problem is? Could it be U7000? In some of mb and mbplogic boards I had it was mostly Phase and UGate that was shorted to ground but this one is ok. No short around IC.

My guess is the Q7000 since it feeds the Q7001 which would explain the 0v on that one. Plus your voltage seems pretty low at Q7000. Usually it is at least 16.5v-17.25v. i have never actually seen one with 18.5v like the schematic says.
Normally they get hit by liquid through the keyboard. I have the board view file, just can't find that U7060. Can you key in the part number somehow in the board viewer? Can you let me know where it is at?