Try to rise the RGB signals BEFORE the JOKE(?) (if present)
That will be the YOKE that you are talking about ;-)
The Yoke is the back of the tube where the connections are.
If you are not familiar with the innerds of a TV, stay well clear. Also a lot of modern TVs have no internal adjustments that are of any use. There may be RGB gain controls on the board on the back of the tube if you are lucky, but if you do not know how to recognise them, don't twiddle.
The board on the back of the tube usually has at least 1000 volts going though it, (which is nothing compared to the 27 THOUSAND volts going to that rubber sucker that us techies call the anode cap)
Scared yet ? You should be
:-o