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Andy
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The MacBook has the green light but doesn't turn on.

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I have a macbook pro that i got that I am trying to trouble shoot, the issue is that when you press the power button nothing happens, no fans, no hard drive spin up, no sound, like it has no pwoer, however, the LED on the MagSafe adapter turns green when plugin, the battery has 1 light that flashes when pressing the test button, I left it plug in with the battery for a few hours and still the battery has the 1 flashing light.

I have re-seat all the cables on the logic board, short the contacts on the logic board for the power button in case it was that, but that didn't work, what I am trying to figure out if this means its something on the logic board or the left I/O board, is there any way to tell this, maybe testing the voltage outputs from the I/O board to the logic board?

System Information

It is a 2.4 GHz Core 2 Duo EMC No: 2136 which I believe is the late 2007 model, it has the nvidia GPU.

Edited by: Andy ( )

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Andy
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I got some life out of the macbook now and here is some trouble shooting I did to get it to now power on:

I did try resetting the SMC but didn't do any good, still didn't power on, so I decided to remove the logic board and left I/O board and look for any components with physical damage and test any fuses soldered to the left I/O, but didn't see any anything, I then test the voltages from the power cable coming from the Left I/O board to the logic board, even when the magsafe plug had the green LED I was getting .5 volts when testing all 3 gray wires being (+) and all 3 black wires being (-) on the power cable at the logic board end which didn't seem right.

So, from that I looked over the I/O board and took the black like tape cover off the bottom of the I/O board and found what looks like one of chip capacitor next one of the IC's that looked burned and so I took a cap off a modem PCI card that no longer works and soldered that in replace of the burned one, and then test the voltage output from the power cable that goes to the logic board and now its outputting 12.6 volts, I went a head and put everything back together, now the green light turns orange and the battery is charging but it still doesn't turn on, waited 5 minutes and then it would turn on!

Seems to work with the battery having some charge to it, and some reason I have to hold the power button 10 seconds with the macbook unplug with no battery and then continue to hold it for another 10 seconds when plugging in the ac adapter and then I can press the power button and it turns on, this is only if I don't have the battery in, not sure if that is normal and it does seem to run hot too.

Wow, congrats! I don't do much in the way of board-level repair, so you're way ahead of me as far as that goes. It's not unusual for the MagSafe AC connector to take a few seconds to register before it will let you power on. I usually wait until it turns green (or orange) before pressing the power button. Make sure to accept your answer, because you solved your own problem!

rdklinc,

Thanks rdklinc though for your help on the trouble shooting tips on these macbooks first to try before taking it completely a part to find the problem.

Andy,

Next time you're opening the MBP top case you could take picts of the part you replaced and post them in this thread.

lemerise,

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rdklinc
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What is the history of this machine? Of course it could have any given kind of damage up to an including a fried board, but it also could be that you may not have an 85W AC adapter. The 60W is not generally powerful enough to start an aluminum Pro, especially when the battery is dead and has no ability to help out. I get these all the time, especially the 17" model, that people have discarded and assumed broken, when in fact they are fine and the owner just had a 60W AC. Assuming the machine is good an 85W will always power on an aluminum Pro, and it's not necessary to have a charge on the battery if you've got an 85W...it will start on even with the battery removed.

Edited by: rdklinc ( )

I don't know the history of this macbook pro, it was one I got cheap from someone as a non-working machine to see if I can fix it without putting a lot of money into it or just sell it for parts. It didn't have the power adapter with it so, I got one off of E-BAY, I made sure it was the original 85W power adapter, it says the power output is 16.5-18.5V with 4.6 Amps Max Model No: A1343. This is the 15" model. So, what I am reading and understand, if it's a 60W ac adapter the system won't power up unless the battery has at least a 15% charge and won't work without the battery unless I have the 85W adapter, is that correct?

Andy,

Correct -- a 60W will not likely power this machine without a charge on the battery, and an 85W will power it with no battery. I would not assume you have a good battery, since there are all kinds of things that could be wrong with it. In fact, I would leave the battery out until you have a computer that powers on, because it will only cloud the issue. From what you've mentioned, your left I/O board does not sound suspicious, although it's impossible to be sure given what I know. Make sure to test the RAM slots -- power up with one module in and the other empty, and then with the other populated and the other empty. And as was suggested, try the SMC reset, and also PRAM. Also, disconnect the hard drive and optical cables...you want to remove all extraneous components until you have the machine running, because until the machine is running they will only complicate the situation. Besides that, there's not a lot you can do other than replace parts. I try to keep scrap machines around for this purpose.

rdklinc,

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yves
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Hi,

thanks for your explanation. I'm facing the same issue and i removed the logic board and left IO board to check for bad component but without success (I tried different RAM module in both slot)

Now, I have only the left I/O board + logic board with 1gb RAM in front of me. Everything else is unplugged.

- with battery (full charged) it's not starting

- with magsafe neither but the battery is charging (orange led on the magsafe + battery led blinking)

I really would like to know if the logic board OR the left I/O board is dead.

Is the logic board + left IO + 1gb ram enough to start and test the logic board ? or do i need to plug something else ?

thanks in advance for any tips.

PS : tomorrow, i ll check the power output ...

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Andy
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I'm not sure if it would power on if you don't have the fans and temperature sensors plugged in, when I test for voltage output to the logic board, I had the I/O board flex cable and power cable plugged into the logic board and one memory module, but I neve

r test turning it on with just that.

If you do try that, in case you didn't know and it does power on with just the logic board and io board, be sure to have the heat sink mounted from keeping the cpu+gpu from burning up.

Have you tried just having the ac adapter and battery removed and holding the power button for 10 secs and remain holding the power button and then plug in the magsafe cable and continue to hold it for 10 secs and then just press the power button as normal to see if it will turn on? If not, give that a try.

I know with mine, I wasn't even getting the battery to charge.

If you want to test at component level, you can start by testing the 2 chip fuses on the IO board, there will be one near the magsafe connector and one on the bottom of the IO board, the fuses are small and soldered on the board, you will see the letter F and some numbers after near the fuses.

You can also short the two contacts on the logic board that have the letters PWR next to them, and will be found in between the memory and dvd drive if the board is still in the case, if the macbook turns on, you know its the power button.

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yves
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Hi Andy,

thanks for your time.

I tried just having the AC adapter and battery removed + holding the power button. When I do that, the mac try then to start (without sucess) but the fan are blowing at maximum speed for 3 seconds and then switching off.

The power button is working. I also tried to start the mac without keyboard but directly by shorting the two contacts on the logic board. The mac also tried to start and shut down (the fan are blowing only 3 seconds).

The 2 fuses seems ok, I checked with controller.

I am more and more afraid that the logic board is gone away.

The full story is that I was working on a document thursday morning, then I moved home and wanted to continue to work but the mac did nt manage to get awake ... I forced a shutdown (pwr button for some seconds) and voila !

I check the voltage on the cable from the left I/O to the motherboard : around 12.5 V. Is this ok ?

I don't know anymore what and where to look for. Any idea ?

Regards.

I have had this issue with a macbook pro before when pressing the power button, the fans spin up for about 5 seconds and then it turns off, but in this case when it turns off it would turn back on with the fans spinning but nothing would display and no boot sound. I'm not sure if this is the same issue you're having, but unfortunately if it is, then the issue is the logic board but I did get it working, I found by putting small amount of pressure on the logic board around the area of the CPU, NB and GPU, I could get it to boot, and found the issue is around the CPU area, my best guess is that it is a BGA solder issue, meaning it wasn't making a good connection on one of the solder points on CPU, maybe from overheating. There might be other ways of doing this, but if you remove the logic board from the case and use a heat gun to re-flow the solder, there are videos and info out on the web to do this.

Andy,

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hckerboy
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Hi, I have the same problem with my macbook unibody MODEL A1278. The problem is when one day my macbook won't turn on. Since I'm too bc during that time, i wasn't able to troubleshoot it but instead, i just left my macbook pro in the drawer. After a couple of days i took it out in the drawer and decided to open the button cover, i found out that the battery swell/bulged. so i took it out then put back the button cover and try to turn it on by plugging the magsafe adapter. it works and run for a couple of days, but after 3 days of using it, after turning it on again, i won't turn on and i noticed that the led light on the adaptor becomes dimmed.

I tried many times but still no luck until now. Anybody encountered the same as my problem? your troubleshooting guide will help me a lot to solve my problem. Thanks in advance.

It could be the I/O board or the ac magsafe adapter

Andy,

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Ugg Lee
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Hi all, I'm facing pretty much the same issue as you guys!!!

I just replaced the magsafe board (DC in board) and now my Macbook doesn't want to switch on anymore.

Before that, everything was working well, I decided to put a new magsafe board because I didnt want to hanging around with 2 batteries (I charges those batteries from an external battery charger)

Could you help me to fix this issue please?

Laurent

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Andrew
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was told by a tech at the Apple Store that after market power adapters those issues. Sometimes they come on sometimes not. They don't have a big enough capacity like the original apple adapters. They will replace apple adapters for free.

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Edited by: Andrew ( )

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