Television and Home Theater

A call to Sony and they have no idea what the "Switching Regulator" is.  Can any one give me more advice on what my problem is and what board it is located on? 

For the past few weeks our television been having a sound problem...

Sometimes we'll turn on the set and there will be no sound. To get the sound back on, we'll have to change the channel.

Sometimes, we'll be watching the television and the picture will go black for a second or two and the sound will go out and the picture will come back on. Again, the sound will not return unless the channel is changed.

At first this seemed sporadic... now daily, There are no blinking lights when this happens.

Recently I acquired a rear projection television dated 1987.  Says "Colortyme".  This is actually a rent to own company so I have no idea exactly who the manufacturer would be. The picture is not as clear as I think it should be.  I am assuming a cleaning is in order.  My question is, can this be done my me or am I going to have to have a tech from someplace?

Thank you for any assistance.