Battery not showing up on A1278 Unibody Macbook Pro: how to troubleshoot & repair.

today I'm gonna try and answer a common troubleshooting question with MacBooks which is I've replaced the battery on my a 1278 model unibody MacBook Pro but it still doesn't recognize the battery how do I know if it's an issue with the motherboard another components in the machine or my battery there's a short and a long answer to this and I'm gonna provide the short one first and then the long answer and the why later long story short if you've replace your battery with one that you believe or know to be good and it's still not working the first thing I would do is check something called the battery indicator LED that's going to be on the side of the computer so if I turn the light off over here and I turn the computer on its side and I press this button you'll be able to see little lights that show up that indicate how much the battery is charged and that component plugs into the computer right over here that's this so if you unplug this and then unplug your battery and then plug your battery back in and then turn your computer on and it recognizes the battery then you can be assured that most likely this is your culprit and if you replace this piece which all you got to do to do that take out the battery unscrew it buy another one on line and replace it everything will work if you unplug this and you've tried a new battery and it still doesn't recognize the battery then you may have a board-level problem so let's go over a little bit of how this circuit works and how it was is that we would troubleshoot this issue now the macbook logic board is going to recognize the battery by speaking to it on a data line over here we have the SMC which is the system management controller this chip is going to manage the system and also tell the system whether or not a battery is connected how to behave when there's a battery connected that's charged versus not charged it's going to activate the charger and it talks to the battery charging chip along with the battery if anything goes wrong with this data line over here if anything goes wrong with the data line then the SMC won't be able to communicate with the battery and the way that I like to figure out if this is the case very quickly is by measuring voltage on a specific power line this chip over here is supposed to produce 12 point 23 volts but the SMC is picky Macs are picky Apple is very picky with all their stuff they go I know why don't you point 23 volts ion 12 point 56 volts so the SMC is going to whine and tell this chip over here which is the is l6 two five nine that 12 point 23 volts isn't good enough I want twelve point 56 volts and it does that on this data line use seven thousand which is the ISL 6259 takes the 16 to 18 volts from the adapter and then over here it turns that into 12 point 56 volts that is the purpose of this circuit that is what it does it takes 16 18 volts and turns it into 12 point 56 but if the SMC doesn't have an opportunity to whine and say I'm a Mac I don't like standards I want to do things my special way then it won't produce 12 point 56 volts it will produce 12 point 23 volts so the first thing that I like to do is measure that voltage rail which is called pp bus g3 hot and I'm gonna take a look on my board view software and it's gonna tell me where I can find that and it's gonna be on a different place and every board this board view software tells me I can find it on that white fuse now you probably don't have a board view and you probably don't have board view software if you're a beginner and you're just trying to fix your own machine and you're watching this but on the a12 78 model MacBook Pro that was asked about there's gonna be a white fuse somewhere around the vicinity of the charger in this area on the newer h-12 78 models the white fuse will be somewhere over here on the older a 1278 models the white fuse will be over there but it will be a white fuse somewhere around here and I strongly suggest that you find some sort of schematic online just to confirm that you're looking at the right thing so I'm gonna bring up my multimeter on the screen I'm gonna put it into voltage mode and we're going to check out that fuse and see what voltage we get now keep in mind that when you're making this measurement you want to unplug the battery because the battery being plugged in is going to actually mess with our measurements so ensure that when you're doing this that you unplug the bad and plug in the charger so unplug battery plug-in charger and we're going to put the microscope on we're going to take our black probe of our multimeter and place that on ground which can be any one of these little screw hole areas so for example we could place our black probe right over here and then we can place the red probe of the meter on the fuse itself now that number that we get is twelve point sixty one volts which means that the SMC is properly communicating with the battery charging chip which means that this data line is functioning which means that if that's the case 99% of the time that that's the case the issue is with the battery you bought some knockoff eBay or Amazon garbage battery and well you got what you paid for that's usually the issue over there is that it's something with the battery not with the motherboard this can also happen if you have a bad battery indicator led in plugged in because what that will do is it will pull down the data line this entire section works based on pulses so the way that this system works is this data line is pulled up to three point 42 volts by this resistor over here and you're going to see on the screen if I were to put an oscilloscope over here you will see a waveform so every time one of these chips wants to talk it's going to short that data line of three point four volts to ground and that shorting between 3.42 volts and zero three point four and zero is going to make a waveform and that waveform represents data now if something is broken over here if let's say the battery indicator LED connection which is this thing right over here is if this battery indicator is broken and shorting our data line to ground then we won't get communication which is why I suggest removing this so if you plug this in and you get twelve point twenty three volts but then you unplug it and you get twelve point 56 volts then you know that the issue is with your battery indicator and not with your motherboard if you unplug this you get 12 point 26 volts then you know that the issue is with something on your motherboard so I'm going to do a quick little demonstration here where I actually short out that data line so if we were to look at our board view over here you would see that this data line works on these are the two pull-up resistors for that data line so I'm just going to solder them together so that it no longer is able to communicate we're gonna solder them both to ground right here with a little jumper wire all right [Applause] now that we have soldered that together I am going to check what the pp bus g3 hull tidge is on the fuse and as you can see we're getting twelve point three volts opposed to the twelve point six we were getting before we're getting twelve point three volts because the SMC is not able to communicate with the is l6 two five nine ship and say that it's a special little Apple snowflake that wants its non-standard voltage and you'll also notice that when we short that data line to ground that the battery level indicator is no longer going to work so if we were to plug in the battery and the battery level indicator shut off the light over here so that I could do this you'll see that it's not giving us any result because the batter that data line has now been shorted to ground and no communication can take place on it but if we remove the wire okay wire has been taken out of the way we plug our battery level indicator back in we plug our battery back in turn off our light turn the Machine around press the button and it is currently able to see the battery now let's suppose that you narrowed it down to where it's clearly a motherboard issue most likely what's going to happen is that you're going to have a short to ground on that data line or the SMC was simply going to be burned out the way you're going to tell what on the board is causing it is by going through the individual components that are on that data line so if we were to look at the motherboard itself and this board view software over here you would be able to see everything on that line by simply clicking a button and this is where I would highly suggest that you find yourself a schematic and board view for your model boards somewhere on Google so when I click over here you'll see that there are several components on the data line the first one is the battery obviously the next one is the battery level indicator the next is this battery charging chip VN is L six two five nine and then when we turn the board around there is a capacitor a diode and then at the top and SMC chip so those are all the different components on the line that can cause the problem a lot of the time it's going to be either the ISL six two five nine chip that's pulling the data line down or it's going to be the SMC chip that's pulling the data line down and in very rare cases it could be one of the capacitors over here that's doing it but it's going to be something on that line and if you want it to be a hundred ten percent sure what you could do is you could inject 3.42 volts from your power supply into that line and see what gets hot for me it's quicker to just remove the components because there's not a lot on that line and leave the SMC for last the SMC is the most difficult chip to replace I'll leave a link to that below the SMC is a chip that has somewhere over 80 to around eighty to a hundred really small solder balls under it making it a real pain to replace and you have to replace it from an identical model donor board we because it has firmware specific to the board which you cannot program which is not fun the most common cause of this issue is typically water damage or somebody using a flathead screwdriver or something like a set of tweezers to pry out the old battery rather than a fingernail if we were to look on the schematic you'll see that this machine is uniquely designed to where the battery connection and the data connection are right next to each other so if you put a screwdriver here you're going to send the 12 volts of the battery to your three volt data in which that usually goes something like this and it goes pop and that will fry the SMC's data line and typically everything else on that line but tip of the time just the SMC now also if you have a multimeter that allows you to you diet use diode mode you can measure the data line to get an idea of if you're getting the proper number in diode mode what you're going to want to have on these data lines and keep in mind when you use diode mode you can have all power unplugged you can have battery unplugged you're going to have the charger unplugged when you have the red probe on ground and the black probe on the data line you're gonna want something around 0.44 12.5 to zero that's what you're going to expect and that's what I'm getting excuse the multimeter software here the decimal point is two to the right of what it's supposed to be but that is 0.5 1/4 which is within range you want somewhere between 0.42 0 to 0.5 to zero in my experience if you have something that's around point to point one point zero zero seven then that means that there's likely a short to ground on the line because the is L six two five nine the SMC the battery indicator LED plugged in or one of the capacitors on that line have shorted to ground I hope that's been helpful for you and I hope that this helps you troubleshoot the issue with your machine you can check out the other videos in this playlist I'm also gonna link another playlist down below which are the most common faults that Apple has either issued recalls for or not issued recalls for but have had serious design flaws with so that you can better learn how to troubleshoot these things and hopefully bring some more max to life do let me know if you have a better way of troubleshooting or if you have any other questions about common issues leave them in the comments below and remember to ring the bell if you want to actually get notifications most of my subscribers don't actually get notified because of YouTube's change in policy so if you want to actually know when we produce videos ring the bell and that's it for today and as always I hope you learned something

Channel: Louis Rossmann

Views: 73,009

Keywords: Macbook, battery, not recognized, X through battery, logic board, repair

Id: fUVoQ2xe_q0

Length: 13min 19sec (799 seconds)

Published: Sat Apr 07 2018