When you take off the back of the TV, you should see a fairly large circuit board with two black chips that are standing vertical. They should each say STK392-XXX (where the X's are typically 100, 110, etc.). The "convergence chips," as they are called, can cost you anywhere from 15-30 dollars depending on where you buy them. You can either go to a TV repair shop and have them order the parts for you, which means there would be a middle man, or you could find some online. www.tvrepairkits.com
has a number of kits available to make the job easier. You just plug in the brand, type, and model number of the TV and you can look at the various kits they offer. Last time I checked it was roughly $70.00 for two chips, soldering guide, online support, and some other stuff.
Another option would be to simply type the chips code (STK3392-XXX) into a search engine (google, yahoo, etc.) and then see if you can buy the chips alone. This would msot definitley be a cheaper option.
Once you have ordered the convergence chips, you are going to have to remove the circuit board/wires and anything attached to the circuit board. Once you have the circuit board out, you are going to need to flip the circuit board over and remove the solder using a soldering gun and some "wick" that will soak up the solder. You will have to do this for both chips, flip the circuit board over, remove the clamps, then remove the chips. Next, I would insert the chip, clamp it in, flip the circuit board back over and begin soldering the pins individually. Do this for both chips.
Chances are, you are also going to have to repalce some resistors as well. To do this you will need a multimeter that measures ohms and a chart telling you how to read resistors. One can be found on www.elexp.com
under the hints/tips section.
All in all, it should only take about an hour with fairly good soldering skills. So you will need a screwdriver with a "star" shaped head, possibly a philips head screw driver, and a steady set of hands to remove the circuit board. Then you will need some desoldering wick, a soldering iron (I would use a 15 watt iron), some small-diameter flux-core solder (rosin), and some patience. There a PLENTY of youtube videos that go through the repair step-by-step.
It's not as bad as it may seem after reading this article. Soldering is not difficult, however, when working with circuity it can be somewhat easy to screw something up. That being said...a little confidence and a lot of patience should get you through it. Good Luck!!!
REMEMBER: UNPLUG THE TV and BE CAREFUL!!!! A TV HAS LOTS OF VOLTAGE STORED IN VARIOUS CAPACITORS AND OTHER DEVICES!!!