the problem is the power supply. if you open the tv and look at the circuit board, you'll notice that the power supply is labeled. there should be an outline around the parts that make up the power supply. You should also notice that the resistors and transistor in this area will have a black burnt area around them. Replace the resistors, the transistor and the smaller capacitor. You may have to replace the larger capacitor also. Use a voltometer to test the larger capcitor before you try and replace it. If you don't have a meter then don't worry about it. Only replace it if the tv still won't turn on. You should have no problem finding the resistors. Just go to radioshack for them. You should calculate the ohms on the resistors before you try to find them. Sometimes the colors of older resistors will look different than new ones. Go to http://www.williamson-labs.com/resistors.htm for a guide to calculate the ohms of resistors. You can also find the smaller capacitor at radioshack, however the transistor and larger capacitor are a pain in the ass to find. NOTE - The transistor may look like an ordinary transistor, but it is an NPN transistor. My advice, which may sound stupid, is to take the transistor to an appliance repair store and ask them if they have an npn transistor for the power supply of a samsung tv. I am unaware of any store that you can find them at. Same goes for the larger capacitor, although it may be completely unnecessary to replace it. If you are inexperienced at tv repair, do not forget the correct placement of the parts. I would suggest taking a piece of clear box tape and taking the parts out one by one and sticking to the tape in the exact position that you found them in on the circuit board. That's it. Your tv's fixed assuming you can find the correct transistor. The txb1940 is a 19inch tv. I also have a 13 inch samsung tv that had the exact same problem.