I can't get my N900 to recognize SDHC cards. At first I thought I could actually have 3 bad microSDHC cards, but once I combed through the logs better I discovered its the back cover. It apparently is never detected as closed. I read in another thread that the cover is detected magnetically, and the inaccessibility of the drive is forced in the kernel. At this point, I dont see ANYthing in my back cover that looks like a metal or magnetic lead. Can someone post a high resolution picture of the inside of their cover? And even better, if you know where this switch is, please circle it so I can inspect my unit. Its brand new, so I need to get on asking for a replacement ASAP, im really hoping Ill just need a replacement back cover if anything..

-Sean-

I think the magnet is inside the device, there's a shiny black metal part on the battery cover, near to the camera slider

good and bad news. I was able to find the region of the N900 where the magnet should be by using an actual magnet. on my case, there is nothing there. Im off to radioshack to buy some magnetic tape...

great news, I took the magnet from a pouch and was able to get it working. Im gonna upload some pics for anyone else with this problem shortly, hopefully nokia will just replace theback cover for me, but at least I can use my cards now.

Hopefully this is helpfull to someone else. THe red circle on the cover appears to be what should fit in the gap, it does not even when the N900 is closed flush. The Red circle on the phone shows the magnet from a magnetic mouse pouch that I cut out and glued on the phone. It does not interfere with the closing of the top, and has had no other impact on the device. I can however as a side benefit, use the cards while the back is off. (WHy would anyone even do that? ;-p)

Cause they want to check / format the card before tentatively putting the fragile feeling back cover back on?

I was going nuts since I knew my 8GB Sandisk worked, just pulled it out of the N82 and cleared it out!

Rebooting N900 now, seems you can't hotswap either! Hopefully it is seen when powered on again...

Nope....no joy. Still not seeing my MicroSD card. Very odd. It looks like there is a magnet there on my back cover, wish I had a picture to confirm.

Going to have to find a magnet now and check, haha.

Well, I blew 2 days on this, so I hope that this helps you. check your dmesg log it will tell you if the card is just corrupt, or if its the same magnetic problem. dmesg |grep mmc and look for the line about the cover open.

Another thing to note is that if your card was encrypted on the other phone, the N900 will not recognize it even with a re-format on the other phone. You have to remove the encryption from it 1st.

Or check dmesg when removing the back cover - you should see the following dmesg entries if your cover magnet is working correctly: