OK, loopback test: When I have plugged the exlink cable to the pc and start putty I get hyroglyphes. When I make a connection between Rx and Tx it stops writing hyroglyphes and I can see what I am typing.
I unplugged all cables from the tv for about have an hour. I plugged in the exlink cable, startet putty (no hyroglyphes) and plugged in the power cable. Then I startet the tv -> nothing, and after 20 minutes the tv shuts down itself !!!
This is the DKU-5 cable I bought: http://www.amazon.de/Datenkabel-Nokia-C ... 564&sr=8-1