Good day.

I just connected my new HDTV to my older audio receiver. The only option that I had with the tv was Optical, so I went and purchased that Toslink cable. Hooked it up and the audio connection is great.

A couple of hours later when it got dark, my daughter turned on the overhead light in the same room that is on a dimmer switch. As soon as she did, the audio connection between the tv and receiver cuts out.

The only think I can figure is that the dimmer switch is old (and inexpensive) and may somehow be causing interference. So, I'm thinking of trying to replace the dimmer with a better one. Is this likely to correct the problem?

That's odd. The TOSLINK connection should be immune from any noise that might be caused by the dimmer.

Are you seeing any other odd behaviour? Have you double checked that the connector is properly plugged in?

It's probable that you didn't insert the optical cable properly and the light from the overhead light is now interfering with the optical input or output. Try shining another light (like a flashlight near the optical input or output) to see (er hear) if my hypothesis is correct and try inserting the optical cable all the way at both ends.

Make sure that you've removed any plastic protectors from the ends of the optical cables and make sure you've inserted them correctly - they should have a flat side of the cable which goes against the flat side of the port. They often also "click" into position.

I appreciate the couple of comments that told me that ruled out the dimmer as a probable cause. That was helpful. Looking a bit more closely, the optical cable was plugged in correctly at both locations. But in setting the who system up, I had tried to make a different audio connection between the tv and my stereo receiver using a RCA-type cable. Once I unplugged that, it is all working correctly!:)

Are you actually using the TV tuner as your source? If you have another source, like a cable or satellite STB) of DD5.1 signals, then that source usually needs to be connected directly to the AV Receiver, rather than "through" the HDTV.

See: http://www.digitalhome.ca/forum/showthread.php?t=17870 DD5.1