Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
SMC Issue on MBP 13 - Hardware Troubleshooting Guide
- Thread starter Dadioh
- Start date
- Sort by reaction score
MacBook Air - No keyboard/trackpad after boot
Hey, does anyone have any ideas on a non-working keyboard/trackpad on an 820-3437-B, but only after boot? It works fine before you get to the OS, but after booting the keyboard and trackpad are non-responsive? Power button still responds though after boot. It's killing me. I have two sitting in front of me with the same exact issue and I'm stuck. Both were minor spills. Working fine otherwise now. Thanks for any help.
Hey, does anyone have any ideas on a non-working keyboard/trackpad on an 820-3437-B, but only after boot? It works fine before you get to the OS, but after booting the keyboard and trackpad are non-responsive? Power button still responds though after boot. It's killing me. I have two sitting in front of me with the same exact issue and I'm stuck. Both were minor spills. Working fine otherwise now. Thanks for any help.
Hi,
I'am analyzing the logic board of a Macbook Pro A1286 and found the schematics and board view for the logic board 820-2523-B.
The macbook will not start at all. There was some liquid spill and keyboard was malfunctioning. After some cleaning around the Bil connector the system does not start anymore!
The SMC bypass is not working.
I checked some voltages:
- 12 V is Ok
- 3,42 V is OK (PP3V42_G3H
- missing 5V and 3,3V: no PP5V_S3 and no PP3V3_S5
It seems it is missing SMC_PM_G2_EN so there is also no PGOOD on U7201 (TSP51125)
Are there other ways to force the SMC to restore functionality.
Thanks for your advise and suggestions.
Leo
sorry i was not around...
you need to be sure that all places showing corrosion is ok and test those SMDs to see if its within range... you need to remove and resolder whats looking bad.... liquid spill is complex and you need first of all make all look like there was no liquid spill.... then you go for troubleshooting... a visual inspection with eyepice/microscope is VERY important.
Without the 3.3V you are dead in the water. SMC_PM_G2_EN is the enable signal for the 3.3V supply. That comes straight from the SMC. I would test the resistance to ground on that signal to see if there is something affecting the signal. Compare to a good board if you have one.
If the issue is due to liquid spill under the SMC leaving residue then one method to try is to heat the SMC with a hot air tool set to about 200C. This can burn off the residue without melting the solder. The issue with a full reflow on a BGA that has residue underneath is that when it outgasses around melted solder balls it can disturb the joints.
Thanks for your advise.
The strange affect is that with only the battery there is no SMC_PM_G2_EN, but with the external power supply (battery is loading and led turns to orange) I have SMC_PM_G2_EN and it seems there are all the S5 voltages but still no power up. PM_SLP_S4_L is not active.
I tried SMC reset with no luck. I checked the SMC_RESET_L on the SMC and that did go low to 0 volt, but no effect.
Should I try to monitor the signal PM_PWRBTN_L or do you have other suggestions.
Hope you can give me some hints.
Broken Inductor Coil on EMC 2419, early 2011 MBP logic board
Hi all,
I am an electrical engineering student in Canada who likes to do hands on work with electronics to gain experiences.
I have recently picked up a 13" MBP early 2011 that does not power up from my friend. He has brought it to Apple and after diagnosis, they said that the logic board is defective and needs to be replaced. He no longer has apple care so I offered to see what I can do.
I have been following this thread for quite a while in hopes of working things out on my own based on other peoples' fixes. But I realized that my skills are still limited. So here is my attempt to seek help:
First off, the machine was not liquid damaged. I have performed the usual checks and the SMC bypass but has found no luck. Then I proceeded to check the G3HOT circuit which enables the SMC to perform the initialization process when the MBP is booting. I have found a picture which showed where the inductor coil is in the circuit, see attachment. However I also found that the coil is actually broken from both sides of the connection, thus it has fallen off and the circuit is actually open right now.
Now what is there that I can do about the inductor? Can i solder both ends of the inductor back on myself, then see if it does the trick?
Also in terms of measuring the voltage at the ends of G3Hot, where are the ends located in this case, which one would normally use to short in order to turn on the board?
Thanks everyone!
Dennis
Hi all,
I am an electrical engineering student in Canada who likes to do hands on work with electronics to gain experiences.
I have recently picked up a 13" MBP early 2011 that does not power up from my friend. He has brought it to Apple and after diagnosis, they said that the logic board is defective and needs to be replaced. He no longer has apple care so I offered to see what I can do.
I have been following this thread for quite a while in hopes of working things out on my own based on other peoples' fixes. But I realized that my skills are still limited. So here is my attempt to seek help:
First off, the machine was not liquid damaged. I have performed the usual checks and the SMC bypass but has found no luck. Then I proceeded to check the G3HOT circuit which enables the SMC to perform the initialization process when the MBP is booting. I have found a picture which showed where the inductor coil is in the circuit, see attachment. However I also found that the coil is actually broken from both sides of the connection, thus it has fallen off and the circuit is actually open right now.
Now what is there that I can do about the inductor? Can i solder both ends of the inductor back on myself, then see if it does the trick?
Also in terms of measuring the voltage at the ends of G3Hot, where are the ends located in this case, which one would normally use to short in order to turn on the board?
Thanks everyone!
Dennis
Attachments
You don't short the G3Hot to get it to start. The startup pads on that model are shown in my attached picture.
You need to replace that inductor to get G3Hot working again. Resolder it and check resistance through it. Should be less than 1 ohm. If the inductor is bad then get a replacement off a donor board. I can send you one if you want. PM me.
Attachments
Hey Dadioh,
Thanks for your reply, you're the ultimate thread master!
I will resolver it back on and see if the resistance matches.
Cheers
Its very hard to have to replace a coil if you had not water damage... I guess you are mistaken ... The coil widing cames from insides and the connector seems loose but it's not because is soldered from whithin
Hey tiagobaracho,
The coil is completely off and I can pick it up. What do you mean it is hard to replace if it's not water damage?
Thanks!
I meant that if its was not water damaged it "almost" impossible to need to be replaced... But if it's "loose" probably there was a impact or something ... If you can, post a close up picture of the coil....
Anyway if it's broke it may be probably the only problem...
ok, i had a 15 inch macbook with same u6990 chip, so i did some measurement on it with and without coils, and reading without coils were exact as the 820-2327 board i have. i replaced the coil on it and resistor blown again, so i must have a short on the 3.42 volt rail..... but how to spot it ? with a lab psu ?
which fuse is blowing ? do you have board number and the fuse number so i can check ?
it is the 470omh resistor R6905. if i remove it, i have 14volt on pin 1. if i put it back it blow that r6905. tried replace L6995 but still the same. dont think 2 l6995 are bad
tnx for help
it is the 470omh resistor R6905. if i remove it, i have 14volt on pin 1. if i put it back it blow that r6905. tried replace L6995 but still the same. dont think 2 l6995 are bad
tnx for help
Ok...
Did you check D6905 as diode ?
Check c6990 if its shorted, this caps connected to DCIN sometimes cracks and get shorted... If it shows short on the board, remove and test it outside..
u6990 has been replaced ? if yes, are you sure you replaced it correctly ? You need to put almost no solder on the ground thermal pad so it can sit correctly... You shoult take it out and check the u6990 between GND and VCC to see if its shorted.. L6995 Coil are hard to get bad.. unless it had water damage... and if you test it, its almost a short anyway.. hard to check by multimeter...
Also check c6999 for short....
get back with this info
https://forums.macrumors.com/posts/20253677/
just did the test by removing all capacitor related to u6990 circuit as in that previous post, but reisistor still blow.
OK...
Well... last thing is removing the coil and connecting a power supply to the r6995 leg, or to the coil number 2 leg on the schematics and make sure there is a short on this 3.42 rail...
If you test the GND to the 2 leg of the coil( when removed) it shows shorted?...
if you dont have a bench power supple, get two AA battery to make 3v and connect to the same pins, but use a very thin copper wire " as a fuse" ( one of the wires from inside the cable... but you need those like headset wires that are very thin.... use like 1cm... if it blows, you have a short on the 3.42 rail..
Use 2 AA alkaline ...
Few other tests..
C6960 shorted?
c6951 shorted?
c7060 shorted?
If all checks out, you may have u7000 sorted... remove and see if short still happens..
Do those tests with the board completely disconnected from LCD, keyboad, trackpad, wifi module... so you can be sure its a short on the board.,..
Last edited:
So today I have managed to solder on the inductor with 330 labeled on it to the terminals, and as measured the resistance between the terminals across the inductor, it showed no change which indicates a bad inductor and open circuit i believe?
Where can I get one of these off of a donor, or can you send me one Dadioh?
I will try to PM you.
Dennis
Inductors when tested in ohms will show short! Your inductor is fine....the problem is someplace else
Is very rare to inductors like this get bad...
The thing is it didn't show short with low resistance, it was a very high value that can't be detected suggesting a open
its almost impossible to both inductors have the same problem.. are u sure you are testing correctly ?
Inductors have a winding inside soldered to both terminals... maybe on removal you unsoldered ?
Inductor are very simple..... just a small copper wire around that ferrite body soldered to the terminals... this is why its a " short"
Anything other than burning it or really hard corrosion will make it show very low resistance.... so check your steps, there should be something you are doing wrong... I fixed already a lot of macbooks and only once or twice i had to replace due to water damage...