A1278 not starting and faint/dim light on charger

Hi there!

I have a question regarding a MacBook Pro A1278 from a customer.

The customer said the macbook did not start from one to another day after having the famous big cross at his battery saying it needed to be replaced for months now.

The customer tried different chargers all to no success.

What i have tried:

2 Different chargers, of wich 1 is brandnew.

Old DC-In board does the same as a brand new DC-In board, they both show up (with or without internal battery connected) as a faint/dim green light.

Disconnected everything, swapped memory etc, it keeps faint/dim.

All ram resets possible, nothing.

Now what we do know is that the battery is faulty but even without the battery attached on the logic board it does the same, it shows no life whatsoever in any way possible.

I do feel that there was alot of dust on the bottom side, i cleared it all but but it seemed quite alot. Also, a few screw points seem to be a little brownish, it almost seemed like water spills corrosion but i could not find any white residue anywhere on the logic board itself.

Anyone that might have another idea or will this probably be a logic board that died here?

Thanks in advance!

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Thanks for the down vote Kevin for trying to help you. Good Luck!

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Do not take it personal mate but it does not help me in any way whatsoever when i already explained everything was disconnected. I understand that you have experience with certain cables causing malfunction but when they are not connected they are certainly being ruled out for being the cause, i figured you already comprehended that when i explained the situation. If you get upvoted people think this can be the cause after reading my story about having everything disconnected already.. anyways.. again.. do not take it personal!

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Besides switching out components, what have you checked? Did you check F6905 to make sure it is showing continuity? Did you check to see if you have power on PPVBAT_G3H? Did you check F7040 for continuity? What voltage do you get on PPDCIN_S5_P3V42G3H? BTW upvotes are a simple way for saying "thank you for trying to help out" Accepting an answer is for " Great it worked", downvotes should be reserved for blatantly wrong answers. downvoting somebody that is trying to help you is a bit harsh and rude.

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I have no experience in checking certain voltages out, since everybody has to do it for the first time there is always time to learn. However when you point out certain components that are disconnected that might be the cause of the malfunction it seems you are on the wrong answer. You are taking this way too personal though, i thank you for helping but like you said yourself downvoting is reserved for wrong answers, wich i think it is when everything you spoke about was already noted as not even connected. Once again, do not take it personal, i rather have you said what u said now right away because when i check up on a schematic and see if certain values are there or not we can get somewhere.

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Kevin, you are talking two different people here "You are taking this way too personal though," I do not take it personal, just trying to get you to check on other things. "However when you point out certain components that are disconnected that might be the cause of the malfunction it seems you are on the wrong answer." I don't think that you will find anywhere that I suggested any of this. Best thing for you to do, is to follow lemerise guidance.

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If you don't get a steady green light on the magsafe tip it's because the charger sense circuit gets an error from the logic board who don't give the OK needed to the charger to send the adequate voltage to power on the machine. Check the voltage on one of the two power pads near the logic board keyboard connector. You need 3.42 volts on one of the two pads. If the logic board is still in the machine, disconnect the keyboard cable before checking the voltage on the power pads because a faulty top case can give you wrong voltage reading. One of the pad is ground so 0 volt and the second pad is G3Hot so 3.42 volts.

To troubleshoot the logic board circuits you'll need the board schematic and the boardview file to identify the components you want to measure on the board. No green light or faint green light means that the "Onewire circuit" is faulty and doesn't provide the 3.42 volts needed to get the steady green light and adequate communication from the SMC to the charger. Also a good visual inspection of the board could help to identify a faulty, corroded or missing component. I use a microscope 10x to 20X for close up view. Pay attention to areas affected by liquid spill.

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Thank you for your reply, i am checking out the board altough i do not have a microscope at hand at the moment ( i do have a very large magnify glass) and i am checking everything out at the moment. I thought to see some brownish (what looked like rust) on the screws mounting circles but i cannot be too sure. Cannot find any other water residu on the logic board itself at all. What did worry me is that i found a little solder tin what looked like it came from the motherboard but i cannot seem to find where it came from, i will have to figure this out because this might as well come from something that is missing now, you never know. I will check the voltages today so thank you for the correct values, i will get back to you as soon as i know more.

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By the way, it might seem un-important but im still gonna say it, when i connected just the magsafe/dc-in and logic board it went faint green again, but after having it connected for a little while i was looking on my phone's BT to connect my payment machine for a customer and i saw a macbook comming up on it?? I am certain it was off though none of the fans were spinning, everything was disconnected so i could not have used the power button unknowingly. Does power go to the BT board with the macbook even being shut down, is this normal, or did power find its way to there showing some circuits indeed are faulty? Perhaps it was just the macbook from the neighboors tho, it might as well have been. Thanks in advance!

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"Does power go to the BT board with the macbook even being shut down, " no it does not.

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The little solder tin you're talking about could be a desoldered 0402 capacitor or resistor detached from the board. If you still have it check it with your magnify glass.

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It definately is not a capacitator. It seems like a tin cap from the bottom of a leg (it is formed like a little shield) I really cannot find where it came from so i am thinking this might not be from the macbook. I do know that this macbook has been opened already before i did so i am just going to forget that i found this. It was sitting on the top of the plastic battery plug that goes into the motherboard, weird location if you ask me. Anyways, those power pads you were talking about, i can only find those on some screenshots such as this one: http://www.insidemylaptop.com/images/Mac...

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The first thing I would do is drop in a fresh battery and run diagnostics again. Next drop in a hard drive with 10.7.5 on it and a new HD/IR cable. Lastly. get a flat rate repair from Apple.

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What i do not understand is that i have had multiple macbooks wich would at least show up as green on the charger while -nothing- was connected just the logic and dc-in board. Also, Apple is no option as i could buy two new macbooks for the customer with the diagnostics costs they ask. Remember if it is the logic board and the customer dont want to proceed with repairs it will cost our company money. We already had too much useless investments like that in the past. What i want to know is why the hdd would be related to the macbook not even spinning its fans with or without anything connected to the logic board, for me that makes little to no sense?

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I have spent so many hours trying to diagnose issues that arise from these bad HD/IR cables and their subsequent destruction of hard drives, that I take it as a matter of course to drop in a known good one just to test. So many times it fixes the issues. I replace with the newer, wider 2012 cables and have only had a couple of those fail.

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I can understand that but would it not completely remove the possibily to see it fail when it is not even hooked on the logic board at all? I mean not even the cable is connected. I have had alot of macbooks in for repair for especially/mostly a problematic DC-In board, and on all of these the charger lights up properly wether or not there is something connected on the logic board or not. What i am trying to grasp is why would it stay dim green with purely a logic board, dc-in and with aswell as without the battery. With your knowledge, would you say the charger would have to stay full green and not go orange when the internal battery is not connected? It does not do anything at the moment, with or without the battery, except for a faint green light, imho it seems rather weird if a cable wich is not attached could be the one causing to malfunction.

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