This is my first post and english is not my native language but i want to contribute to the community with a so long desired solution for LG 42/47/55LM6200.
this journey begins with a not so good idea from LG....yes that one "YOU CANNOT PASS DTS" through your TV if you are on america due to licenses issues/fees/etc, etc, etc. so....
1.- Upgrade your tv to the latest firmware (current 03.21.40 http://www.lg.com/us/support-product/lg-42LM6200
2.- Get/obtain a RCA control like this http://www.amazon.com/RCA-RCRN08GR-Device-Universal-Backlit/dp/B003EYV21K
I believe that second step is the most important because particularly speaking we are not going to use RCA remote control for bringing on the EZ menu only. We're looking for an ADVANCED EZ menu.
3.- When you already have your new remote control use code 10856 for program and notice the most buttons won't be working (so please get your original lg remote control cause will become handy) push down button 2 to bring on the EZ MENU and then push down button 3 to bring the Advanced EZ menu (In-start will be there too) LOOK for NSU Mode OPTION and change it from user to engineer.
Explanation: why do we need NSU Engineering Mode? well quite simple...when your TV is in NSU E-Mode will be connecting to LG alternate servers to download new unreleased firmwares.
4.- Now go to your typical menu and look for new updates. Your tv will show that a new fimware has been found and available for download (firmware 04.82.02) please update your TV as fast as you can...... that's the key.
5.- After upgrade process has finished take back your RCA remote control and go to normal EZ Menu. This time options will be available for modifying and particularly speaking you cannot change country group but you DON'T NEED IT. Just look for AC3 EDID option and change it from PCM to AC3.
6.- Wait almost there….. well actually we are there we have DTS passthrough...but wait THERE'S A BUG. keep reading.
Take this in mind…. your DVR or HT will displayed effectively DTS sound but you won't hear a sound. For some reason (probably a beta firmware) you need to go to menu on your TV and look for sound options and change your optical sound output from automatic to PCM and then go back again to automatic after doing that full DTS 5.1/7.1 track will be detected.
Best regards, JF (rahaziel)