The RCA outputs should work. You might check to make sure they're plugged in the correct jacks. Does the output specifically say "Audio Out" as noted in #1 in the below schematic?
You might try to toggle the external speakers settings in the audio menu.
If this doesn't work, you might consult the Samsung Customer Service Center in your area for additional troubleshooting.
Keep me posted.
I have just bought a Samsung LCD TV. The internal speakers are working when using the digital TV channels. However, if I select external speakers I get no sound. I have connected the RCA cables on the back of the TV to my analogue amplifier (which works with the DVD RCA cables).
Should the RCA output work?