There are several things that can cause this.
The most common is the horizontal circuit, this circuit is responsible for deflecting the picture from left to righ ton the tv screen. When it goes bad it will shut down the set just like yours.... This repair normally runs around $250.
However this could also be caused by the vertical circuit, power supply, and high voltage circuit to name a few. The average repair price for any of these is $400-$700 depending on exactly what is found.
However to determine exactly what the problem is will require troubleshooting. Some knowledge of electronics and a multimeter will be needed for this. If you have this knowledge/tools I will be more than happy to walk you through the troubleshooting of this set and determine what is wrong. Also most repairs will require good soldering skills so you will need these as well for us to repair the tv after diagnosis. If you don't have any of this then a repairman would be your next step.
I am sorry to bring you the bad news on this one, you definitely have an internal failure in the set that it putting it into shut down.
However, with all that said, we would never recommend a repair on a set with the age of yours and this is why…. See when these sets get old they become brittle, just opening them up and moving he boards around to do the repair can cause 5 more problems next week, solder connections are prone to letting go and becoming bad just from moving it around. The components inside the set also have connections in them smaller than the hair on your head and these can let go just from being moved around. In addition to this parts availability starts to become a problem, if you got it repaired now and then in a week you had another problem and they couldn’t get the parts needed you would have wasted your money on the first repair and still have to throw the tv away.
If you would like any additional information or have more questions please don't hesitate to ask!
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