Thomson TV problem

Sounds like The main power supply regulator section circuit fault. Either it will be a separate board, or the part of main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Pull up older posts. http://electro-medical.blogspot.com/
It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.

Fault to the main power supply regulator section. Either it will be a separate board, or the part of main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
http://electro-medical.blogspot.com/
http://electronicshelponline.blogspot.com/
It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.

Fault with the main power supply regulator board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
http://electronicshelponline.blogspot.com/
It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.

you have a back light problem either the invertor is faulty or the screen

not a diy job might be dry joints on invertor board best left to an engineer

Best advise! Sell it or exchange it for a better TV. Your old TV
may not more than Rs. 800/=

Now a days you do not get talented technicians and original
spares. Do not attach sentiments to the TV. If so keep it in one corner
and go for another TV.

thomsom or RCA tv;s are known for power supply issues
check yours for puffed up can like devices on both main and power board if you find one the value is on the side replace it and you will have fixed it won't hurt to try

replaced main board

i think you have a problem with your stand by power board.
There is a service kit available but this has to be fitted by a service engineer.
it is available from www.tvs-services.com or call 01245392539 monday to friday 9 to 5

If what your saying is that there are vertical stripes down the screen, You have a screen drive problem my friend. This could mean you will need to change the entire main board, the screen driver board if it is separate on this set, or the main LCD panel itself. These boards do not have any parts available for them and must be replace as a whole unit. Good Luck