http://elektrotanya.com/thomson_20lb020s4_23lb020s4_30lb020s4_ch_lcd02tc_sm.pdf/download.html
here is your service manual.
Well, it is nearly always my professional opinion that one should always get a "Quote" from the manufacturers recommended service center,
Thomson in your case, please contact a local or head office and ask for a referral to an Authorised service center. I cannot stress how important that last point is. It is even worth the cost of shipping. You see an authorised service agent, will have trained staff, trained on their brand, also they have first hand access to parts, original parts. This will actually save you money and ensure you can actually get it back fixed. Of course asking for a "Quote" also gives on the option of repair or replace. Often my clients,do not go through with repair, unless it is moderate, but in some of the more costly jobs they see it, as do i, that a replacement, with a warranty, is a better option. As an aside here, one could then tear the TV down, and sell the Known Good bits. You'd be surprised who needs parts, i myself often must by from third party sources to effect a repair. So money could be recouped, somewhat,and help out someone else.