If you lift up the kick-stand, you'll see a small rectangle object glued on the back cover (not on the kick-stand)..

Mine fell off, noticed it was just glued on with a just few drips of glue.
This magnet controls the camera on/off...

Had to glue it back on, quite easy to lose if it comes off..

confirmed by irc user Shinkamui, who lost his.

I'm not very sure about this, but isn't the magnet just to held the kickstand in place? I always thought the camera on/off is controlled by some sort of photo sensor, because i noticed there's a white and black color strip on the lower inner part of the lens cover.
anyways, thanks for the heads up, will keep an eye on that little fella

It might be doing double duty. One end holds the stand in place, the other end tells the n900 that its back cover is on.

i'd say that it isn't for the camera but for microsd slot (disable mounting while back cover isn't in place)

Whatever duty it does, it could come off (deja vu all over again.. many earlier tablet users lost a few magnets), so it's a good idea to keep an eye on it. Thanks bugelrex - I wasn't aware there was one there.

Theres a magnet on the kickstand too.

The magnet on and under the Kickstand (in the body) is to hold it on place when closed. The backcover appears to be too thin to engineer a spring mechanics to hold the kickstand open and closed at both extremes of movement.

EDIT: See my post here: http://talk.maemo.org/showpost.php?p...8&postcount=13

That magnet under the kickstand is how the N900 detects whether the backcover is off or not. If that magnet is missing, the N900 can't detect the backcover being on the N900. And in turn won't enable and mount the SD card.

Lost mine a few days ago, took me a while to figure out why my N900 wouldn't recognize my Micro SD card. Managed to rig up a temporary fix for it.

I poached the magnet from a cheap set of earbud headphones.....


Cleaned out the left over glue....


Cut the magnet to size (My magnet was round, obviously, depending on your patients, you could do a much cleaner job cutting than I did), and glued it into place.... (I also used a permanent marker to colour the magnet black)


and voila.....


It's a bit hacked together, but it's rock solid and should last until I replace either the device or the back cover. No points for pretty though!

I had the same problem, my memory card disappeared suddenly.
I was lucky to read this and I did find the original magnet and glued it on.