Tv/dvd combos do not use a tv codeset, but a dvd one instead, that why searching tv codes fails.
I suggst searching dvd codes by volume with tv on and muted:
1. av1 or av2
2. press and hold MUTE & SELECT for two blinks
3. enter 9 9 1
4. enter 2
5. press and release VOLUME UP
6. point the remote at the tv and keep pressing & releasing CH UP key, if and when the volume changes
7. press SELECT to lock in code
To get the volume and punch it through to ALL devices:
1. av1 or av2
2. press and hold MUTE & SELECT for two blinks
3. enter 9 9 3
4. press SELECT
You will have to abandon the tv device, and that includes the TV ON & OFF keys. Although there will have to be a tv code programmed to the tv device at all times or the volume keys won't work at all. It doesn't have to be your tv brands code, some legitimate 5 digit code starting with 1****.