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tigress666

macrumors 68040
Original poster
Apr 14, 2010
3,288
17
Washington State
Ok, so I have a 2010 13" MBP.

I usually use it connected to my desktop monitor. First I used it in clamshell mode and now I use it open with my desktop monitor in back.

Also more recently (like for a week/week and a half), I have not been turning off my MBP each night. This seems to be where the trouble started (I have no idea why, and apparently a restart doesn't fix it anyways).

A few days ago I noticed that if I shut the computer (to put it to sleep), that it would wake up the monitor (Honestly, I think that's how it is supposed to work, but it had been letting me get away with putting it to sleep by closing it). But then I noticed that when I opened it, it didn't always turn on the desktop monitor (which I always have on so it just wakes up when the computer sends it info). It seemed the best way to fix this was to close the computer and open it again (at first putting it to sleep and waking it might work).

That worked for a short while. Then that wouldn't turn the desktop monitor on (though it would let me move my windows into it like it was on). But if you went to display options you could still gather windows and it would detect displays. And then I noticed eventually the desktop monitor would eventually turn on randomly.

Well, today, it just acts like there is no monitor attached period. You can't move a window into the invisible desktop monitor. Hitting detect displays does nothing and so does hitting gather windows. If you close the MPB, it doesn't turn on the desktop monitor. Try to disconnect the monitor and reconnect does nothing.

I'll add that if I disconnect the computer the monitor says "Cable disconnected" (It apparently says this as well when the computer is off as I have another MB that I just tested it and when the MB was off, it would say "Cable disconnected"). But when connected to the MBP, it says "No input signal" (Apparently though if it is connected to the MBP when the MBP is turned off it just says "No input". Only difference between the two is the MBP was plugged in, the MB was not. So I am assuming that it detects electricity coming from the connection to decide if it is getting no input vs. disconnected).

Any suggestions?
 
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I'm really hoping some one has a suggestion?

I've tried re-installing from an image a week ago on time machine, re-installed Snow leopard (from the disc I had bought for my previous mac, but just found the disc that came with this mac so I'll try that too), resetting the pram, resetting something ? (option control shift power to start it up), and nothing has worked.

At some point I'm thinking maybe re-installing the OSX as a clean install and seeing if that does anything at all (I don't want to cause that involves the time it takes to do that just to see if that works + the time to re-install OSX from the time machine backup).

I am planning on going to the genius tomorrow and hopefully even though my mac is out of warranty (by a month) maybe they'll be nice and at least do a few things (maybe at least connect it to another monitor to see if the problem is either my hardware or the dvi converter which isn't apple's but has worked until now).
 
Just in case this thread shows up in a search for some one else trying to find out why their macbook isn't detecting the external monitor:

I went to the apple store today and they helped me rule out hardware.

It turns out my VGA to mini display port adapter was bad (he says it is hardly ever the port on the computer that goes bad).

So, if you have tried all sorts of software fixes as well as checked your monitor connections and monitor (which I knew it wasn't that cause the monitor worked with my other macbook), maybe it's that.

I ponied up the money and bought an official apple adapter (I had bought some cheap knock off on Amazon) this time as I just didn't want to deal with that again (I mean the knock off lasted a year so it would take about three years I think to equal the price of apple's) and I know that my macbook has the official adapter and I've never had issues with it (It's now 4 years old).
 
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