Ok so you have an older plasma monitor with no TV tuner and no hdmi.
Tell me what equipment you need to hook up, there is more then one "cablebox" so I have no idea what box you have or what outputs it has available.
If there is no model number on the equipment then I at least need to know what kind of connections it has.
RCA = Red, White, Yellow round plugs
SVIDEO - black circle with multiple pins in it, looks similar to an old ps2 port that an older keyboard or mouse would use
VGA - Trapezoid port with 15 pins, on the device this will be a female end and it will stick out, often it is blue in color
SERIAL - Also trapezoid shaped but with only 9 male pins
DVI - wider connecter then VGA and on one side has a rectangular pin, this will...