I have FM transmitter enabled, but anyway it doesn't work, despite the appropriate option is checked.

But... accidentally I found, that it works when I press (and hold) a button in a left part of physical keyboard!

Seems to be hardware problem?

Could anybody advice me how to check hardware (logs etc.)?

Not sure if the software would notice if the antenna is disconnected.

The warranty should cover it, of course.

i have the same problem! but... i havent tested if the keyboard pressing thingy works...

eeeur - which button did you press to get the fm transmitter to work? i might give that a shot later to see if i can get the same fix

I also have the same problem! Only works if one of the arrow-keys is pressed.

i have the same problem has anyone found a solution, or it is a hardware problem and i have to take it back to service?

The same problem here.

I bought two N900 from Amazon.com in USA. One in Feb 2010, and the other a month later. They both show the same problem.

May be that problem is quite common?

I can achieve normal transmission when while media player is playing something I press and hold the down arrow on the hardware keyboard. The active application may be different. The calculator for example.

If no key is pressed there is no carrier frequency. Noise only from the receiver.

Did a little testing to see what happens when the key is pressed.

Nothing releted chaged in the /sys/class/i2c-adapter/ tree when the key was pressed and released later.

Verified by dumping file's content this way:
root@Nokia-N900-42-11:/sys/class/i2c-adapter# for i in `seq 1 1000`; do find . -type f | while read f; do echo -n "$f: "; cat $f 2>/dev/null; done > ~/radio-test/res$i; echo $i; done

No related changes found in diffs between files.

That's a hardware problem!

No need to press any keys at all. Just press the thin plastic part between the space bar and the box edge. Starts transmitting

Problem fixed.
Disassembling a little N900 I got access to the FM Transmitter antenna. The GND pin was not bended enough to make firm connection to the PCB.

I bended it just a little more as shown on the attached photo. That resolved my issue.

Be smart. Send your device to Nokia for repair if you have the same problem

Ha, just tested mine, (has worked once, long time ago), and sure enough, if I press down around the arrow keys, it works wonderfully! Don't have to press the buttons all the way, just a little.

I too got mine from Amazon USA, around Feb or March.

Anybody know how long Nokia's warrant turn around is?