I looked up the codes given by the TV manufacturer, a four digit code rather than the five digit code Comcast provides, and the very first one worked! Google 'remote control codes for _____ ' (your TV brand and/or model) and use the code provided by the TV maker.
I just got another remote because I was having trouble with the last one. Now I can't seem to get this remote to turn my TV on or off. It will change stations (slowly), but won't turn the TV on and off. Help if you can. Thanks
The Comcast remotes also have a search feature. With a special cable, you can program the Comcast remote (if it has the 6-pin header in the battery compartment) with your computer and create your own upgrade code.
One problem with store-brand TV's is that they are often made by multiple 3rd party manufacturers, and each manufacturer may use a different code set.
Problems getting the Comcast Remote programmed for your TV? Here is my personal solution, maybe it will help you.
I purchased a new HD TV from Best Buy. It was an Insignia Brand 22" TV to be used in a bedroom. To go with the new TV, I also upgraded to an HD Cable Box from Comcast. I tried to program the Comcast remote to also control the TV, so I would only have to use one remote for both. I carefully followed the Comcast instructions, but the provided Setup Codes would not work. I called Comcast customer service for help. The service representative led me through the SAME programming steps with the SAME Setup Codes. The service rep said that was all she could do, so I would just have to use 2 remotes, one for Comcast, and the Insignia remote for the TV.
I overcame this frustration by going to the TV Manufacturer's Website and there I was able to look up my specific model TV and on that page find a code for the cable service provider's remote. Worked like a charm. My Comcast remote now controls both. I am not sure why Comcast did not do this simple research and added it to their list of codes.