Could you be more specific? What do you need and RS232 cable for? Old serial device of some kind? Also, what Operating System is on your Dell machine, that will actually make a difference.
Analog component signals are completely different to digital HDMI. There is no simple adaptor cable because the analog signals require processing to convert to digital. There are converter units that...
To fit Henderson Merlin cables, Cones you should look at the fitting instructions on www.garagedoor-spares.com or visit
http://www.garagedoor-spares.com/henderson_cone_fitting.pdf
This...