If your coax cable is damaged, there are some steps you can take to repair the damaged cable rather then changing the whole line. This will save you time and money, because a repair is less expensive then a new coax line. After the line is repaired there should be no difference noticed in signal strength for the TV. If you do notice a signal-strength loss and have followed all the proper steps for repair, then you will need to change the line because the line is damaged beyond repair.
Paint on liquid electrical tape if the insulation covering is damaged but the line is intact. When dry, it will create a new insulation barrier.
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Cut the damaged area of the wire out if the coaxial cable has been cut into. You will need some slack wire to pull.
Twist the new ends onto each wire end that you just cut back. Strip back 1/2 of the outer black insulation leaving the silver braided wire to fold over as you twist on the end. Strip 1/2 of the inner insulation to expose the copper wire in the middle. Turn the ends clockwise to screw them on.
Join the two ends together with the coax joiner.
If the end of the coaxial cable where it screws into your TV is damaged, put on a new end. Cut off the old end and twist on a new one by simply turning the new end clockwise.
Things You'll Need
Twist-on coax ends
Coax cable joiner, male on both ends (if needed)
Liquid electrical tape