I own a TCL 55 inch TV and my DirecTV RC66RX remote controls the Volume & Input Select
I just got the TCL 75S421 and my other my DirecTV RC66RX remote control will NOT control the Volume & Input Select. It does control some functions.
IF i take the remote used on my 75 inch and take it upstairs to my 55 inch TV, the volume DOES adjust !!
If I take the remote from my 55 inch downstairs to my 75 inch tv, the volume does NOT adjust.
what's going on ?
The white directv remotes add an extra signal to every command, it may make the IR unrecognizable to the 75". Where the 55" isn't as sensitive to signals it accepts. Try the following steps:
2. press and hold MUTE & SELECT for two blinks, release
3. enter 1 2 0 4 9
To enable the input key:
3. enter 9 6 0
To disable the extra signal:
3. enter 9 6 3
4. press CH down
I will try when I get home. I swear I've tried every code, but that code does not ring a bell !
[nor do the additional tips]
I'll report back !!
It WORKED !!
THE THING THAT I NEEDED TO DO WAS RESET THE REMOTE BACK TO RF MODE.
After that, I did the first two steps you suggested and it worked fine!!