I need to know if is it possible to get the right schematics from any
site or any friend. I got some schematics but they differ from the
television set.

If you look for schematics on the internet it often helps if you know what
chassis the TV has. I couldn't find 28CT7692 in the list I have. The
closest match I could find (but that was not a very close match) suggests
it is a 2B chassis from around 1988. For some models you can download the
schematics from the internet (though the quality of the scans is often
poor).

You might try your luck he
http://schema99.host.sk/
and he
http://users.pandora.be/tvfixer/

If that fails there are companies that sell service manuals, don't have
URL's handy though.

In the same TV I can't localize the battery used to keep the setings
when the television is turned off.

It is very well possible that that TV uses EEPROM rather than RAM with
battery backup to store the setting.

--
Peter van Merkerk
peter.van.merkerk(at)dse.nl