Yes, you can scrap cable boxes but only if you own them outright. Your cable or satellite company typically requires that you return their equipment when you cancel their service.
This is why they commonly charge a small monthly lease fee for each cable box that you have; you never really own the box.
If you canceled your service and did not return the cable box and was charged an equipment fee, then you own the box.
Cable and satellite boxes contain few different types of scrap. The outer casing of them is made of steel. They have transformers and motors within them that contain copper.
There are many aluminum parts as well as bits of scrap gold that can be found within these boxes as well. Electronic scrap collectors and many scrap yards will buy the motherboard as is if you are able to get the casing off without damaging it.
If you are thinking of making a trip down to your local scrap yard with a single cable box worth of scrap I would hold off. Many things that you have around the house have motherboards in them.
Save up a few things instead. It is fine to sell nonworking electronic scrap. With that said, be on the look out for either of these items especially at garage sales and in friends or family member’s garages.
Old electronics, tv’s and so forth are what you should keep an eye out for because most have a lot more scrap metal within them than flat-screen televisions and everything else that is streamlined today.