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Replaced the Logic Board and the left i/o board - now what?

No startup chime, no video, solid sleep LED, optical drive makes noise, and after staying on for a while, the part underneath the F keys gets hot.

I had a question about this same problem, and it was suggested the i/o board may have been the culprit, so I replaced it. Both the LB and the i/o board were brand new - not used or refurbished.

I followed the instructions here to the T, but I am just lost - I don't have the knowledge to know what to look for or troubleshoot beyond the obvious things I've read about.

Could it be bad wires? connectors? if my Fans were not working, could it cause the MBP to fail the POST?


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Nothing? Any ideas guys?


There's nothing to give a diagnosis with. "I had a question about this same problem" what's that?. KISS Start all over and give the basics. Start with the light on the AC adapter. Nobody gave an answer because of your approach. Just tell us what's happening and your machines history. Sorry to be so blunt.


Sorry Mayer, I started another question when this first happened and received a lot of help and insight and advice. But it turned out (evidently) my problem is not what I and others thought it might be. So I decided to start up an new question.

About a month ago - my MBP was working just fine. I brought it home from work on day, pressed the power key - but all I got was a solid LED sleep light, no startup chime, no video to the display, no other noises other than the optical drive was spinning (I have a disc in it). The light on the AC adapter is the amber color - but once the battery is fully charged, changes to green, as usual. If left "on" in this state, the area beneath the F-keys gets very warm - as if the processor is working, but you don't hear anything - no fans, nothing other than the optical drive. I have to push the power button to turn it off again.


If I hold down the power button and keep holding, after 6 secs the LED light blinks several times and then goes off again - but you can still hear the optical drive spin.

It was suggested that I might have a bad Logic Board, so I installed a brand new one using the guides on this site, and it still exhibited the EXACT same symptoms. So, I posted a question about that here on this site and that is where I got the help I referred to above.

It was suggested there that instead of a bad LB, my left i/o board might be the culprit. So I installed a brand new one and again (keeping the new LB in the computer as well) - the EXACT same symptoms as before. NO CHANGE.

I checked for burned wires, bad connections, or anything that appeared to be damaged, but honestly, I don't know enough about this to even be able to tell if something has gone bad.

I can follow directions well, but diagnosing beyond the obvious is something I am not gifted with.

This is all the info I can think of to report.



Oh yeah - I did try to zap the PRAM and other easy solutions, but since this is not passing the POST, I don't think that would have done much anyway.


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Please disconnect the hard drive, remove the battery and try starting up. Let me know your results including any lights and/or sounds. You said there was a disk in the optical drive, what is it? If it's a system installation disk, is it the original disk that came with your computer? Did you buy this unit new? Has it ever gotten wet? Where did the new parts come from?

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OK - I'll disconnect the HD and the battery and try that - will report that as soon as I can.

One of my very first attempts at troubleshooting was to put in a OSX (Leopard) install disc to see if I could startup from that and see if anything was wrong with the HD. The disc is still in.

I bought the MBP used on eBay. It had just come off a lease. I got it over a year ago and have had no problems till now. As long as I have had it, it's never been wet.

The new parts I got from eBay - The i/o board I got from a seller called "applecomponents"

The Logic Board: eBay - from a seller called "vectusllc"

I'n not sure those will come up, but those are the items I got. Both came with warranties and were advertised as new.


OK - I took out the hard drive and battery. And when plugging in the AC adapter - I got a green light. I pressed the power button and got the same no startup sound, solid LED light and heard the optical drive spinning up. but nothing else.


Try starting up holding down the trackpad button and see if the disk ejects. Tell me about the system DVD, is it a retail install, is it gray, if so what is the part number on it? Tell about your RAM, original and added.


OK Thanks Mayer! I appreciate your patience and thoroughness. I started up holding down the trackpad button, but no eject and has the same symptoms as before. About that system DVD - it is a duplicate copy I made from a retail version. My mac did not come with any discs when I bought it. Not certain of part no of the retail DVD, but my computer already came with Leopard on it - so I never used the DVD on it. I was just attempting to see if I could start it from the DVD. But the only difference between having it in the drive and not is that you can hear it spin up. Everything else is the same.


OH yeah, RAM - is original.


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You may try to remove completely the top case, disconnect the hard drive, the optical drive, airport card, bluethoot cable, well everything you can disconnect from the logic board but let the dc in board connected then find the two power pad contacts on the logic board (you should see a white power icon, or PWR written somewhere). Connect the AC adapter and try to briefly bridge the two power pads with a small jeweler flat screwdriver. If the MBP powers up and you see the question mark onscreen then you know the logic board is OK and you can connect the disconnected components once at the time powering the machine between each connection until you find the culprit.

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So, just to clarify, if only just a few (or one) components are connected to the LB, and the LB is good, I would still power up using this bridging method to test each component? And I'll know the bad component by the computer NOT powering up at all? Is this correct?

Someone else in another place mentioned a possible bad reed switch/sleep sensor.


Yes you got it Jerry. The idea is to first test the logic board without other parts connected to it and if it's working then find the culprit. I often checked logic boards alone without anything connect to them but the DC in board, a usb keyboard and an external monitor and headphone to ear the chime at startup.

Concerning the sleep sensor, yes it could be a problem but often a bad cable or a faulty top case can generate the kind of problem you're stuck with.


Thanks. I may try this!!


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jerrywickham zal eeuwig dankbaar zijn.

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