Why do some cable channels not have any sound?

I have Time Warner digital cable, and certain channels have sound, but no picture. Is it my tv set, or cable?

• The channels that don't come in right, have great sound, but black with small colored blocks in a few spots.

• Answer:

  OK here is your problem ignore the rest call time Warner for a service call they dont charge for service unlike dish the problem is you have a low signal level coming to the box this can be caused by a number of factors bad cable to house from pole bad fittings on the cable etc or the one problem that happens most of the time is the customer decides to play cable guy and installs a splitter from radio shack on the line leading to the cable box that decreases the signal to the point where it starts to break up example black screen or lines and squares appearing on the screen this is called pixelation call the company they will fix it at no charge