No Sound!! Problem with New HD TV connecting to MDP-.HDMI with RCA cable

This is regarding connecting my macbook pro to the TV. I had an HD tv, it burned out and so I bought a new one (much better and obviously newer than my last one). The one I have now is a Samsung ES5500 (see below for link to more info) but now that I've installed my new tv and connected my computer no sound is transferred to the TV.

Samsung ES5500 (UE-46ES5500) LED LCD TV Review | AVForums.com - UK Online

With my old TV I had the Mac Mini Display to HDMI adaptor plugged into the HDMI port in the TV, along with an RCA chord. My macbook pro is from 2009 therefore the mini display port cannot transmit the audio, but with my previous flat screen tv it worked just fine with the RCA cable in addition on the HDMI setting.

Can anyone verify whether there is some setting on the mac to change (I've checked in system preferences for both sound and display and exhausted all the options) or is there a setting on my TV I should know about? I hope I don't have to buy any new chords, it doesn't make sense to me that it worked perfectly well without changing any settings on my mac for my old TV and now this new and better one will not take the sound?

Please help I am going nuts I've spent the entire day trying to figure this out

Thanks!!

The old TV - the HDMI cable plugged into a HDMI port that was also labeled "DVI". The RCA cable also plugged into an audio port labeled "DVI".

You new TV - the HDMI cable must be plugged into a HDMI port that is also labeled "DVI". Your separate audio cable must be plugged into an audio port labeled "DVI".
Did not look up your specific model, but every Samsung I've seen to date uses a 3.5mm stereo mini-plug (the same as on your Mac) - not RCA - for that DVI audio port.

Look at the back of the TV and find the ports with the "DVI" labeling on them.
If you're like me, you'll need to grab a flashlight and your glasses.

After you know you have everything plugged in via the DVI ports and still have issues, give a post back about possible TV settings. Most Samsungs will auto pick up the separate audio once connected correctly.

Thank you Bobtomay!!

Perfect response- totally helpful. Thank goodness you knew something about Samsung tvs as well. As soon as I got a mini stereo chord instead of the RCA chord it worked. You were totally right about the DVI audio port, and also it was necessary to use the HDMI port on the TV that was labeled "DVI" as well (one was, one wasn't)

It appears also that if you don't have a mini stereo chord, (for others who have this problem and have an RCA chord already) it appears you can buy an adaptor ( like this: Amazon.com: Rca To Mini-stereo Adapter - Rca - Female - Mini-phone 3.5 Mm - Male: Electronics )

I'm not sure if the quality will be better with that, or the same, who knows but I think you probably have either of these options if you have a samsung tv that only has a mini stereo port in the back for DVI audio in!

Thanks again Bob- great response and very quick too. you saved the day!!!