Hi

I've bought a 52PFL8605D which has firmware Q552-0.133.3.0 installed.
I can play mkv videos but have no sound on tv. Newest firmware seems to be 140.046, right?
After reading that a lot of users having problems with ambilight, sound drops etc. with new firmware I'm in doubt to upgrade to this firmware.
Questions:
1. How can I get older firmwares (like the orig one which is currently installed
2. Can I downgrade back to Q552-0.133.3.0 (sticky post says your at your own ...)
Mi mkv file sound is A52 i think this is the same as AC3 right?

Thanks for any help