My KDL-40W4100 has the same problem, just fewer lines. Mine went from two to eight lines over a couple of months before I retired it. It's the TCON board. See my messages for more on my experience trying to replace this board myself:
I'm just going to go ahead and quote the second message, which discusses Sony's rude, unhelpful phone "support", which directed me to the worst rip-off repair site I encountered previously doing my own research, a site going by an alias on the Internet, a site I previously blocked forever from my google searches.
That's a safe bet. Sony is not being nearly so generous when it comes to faulty T-CON boards in the W4100 series, for which they want $413 and won't accept returns for any reason whatsoever. Apparently, it's a widespread problem, because I've been through three used boards, which solved my problem completely, but caused different worse problems of their own, and all three exhibited different problems. In each case, putting my board back in returned me to my original problem. I know I'm ordering the right part, because Sony has published a document on the subject including part numbers for serial number ranges. More on my experience with this problem here:
The only conclusion is that the three companies that shipped me parts are salvaging broken TVs, harvesting the parts, and selling them without testing them. At least shopjimmy.com and retechtv.com issued full refunds and prepaid return labels without any hassle. The other company lied to me repeatedly about the return label. The fourth company I ordered from didn't ship me anything. I had to get my credit card company involved in the last two.
I did call Sony and got a couple of heavily accented "agents", one of which rudely suggested, "Why don't you just buy a new TV so you won't have to worry about this?" That's real nice considering I spent $1700 on the TV and used it maybe a couple of hours a day for 4 years. Then she blew me off to "Herman's TV Repair", whose phone number matched encompassparts.com, a site I had blocked long ago from google search results due to its ridiculous pricing, which is even worse than Sony's, with a $180 refundable (yeah right) "rebuild fee" on top of the $413. That's another thing. Many of these parts stores go by multiple names, and their web sites conceal them. For example, "HDTV PartsStore" is really Tri-State Module, and don't get me started with the Asian shops in NYC. I've blocked a couple dozen of these scam sites in google search.
Oh, if you still care, the Sony document on the TCON board can be found here:
You need to match the part number to TV serial number to have any hope of success. Oh, I almost forgot my follow-up message, where I went into even more detail on the various TCON failure modes I encountered:
FWIW, all three of the defective TCON boards I bought and returned solved my minor problem completely and produced a picture along with or before exhibiting their own problems, which were completely different than mine, as well as each other. The first one was perfectly fine for about a minute after turning the TV on, after which the picture went completely nuts and stayed that way. So apparently that one was unstable once it warmed up. The next two were bad immediately upon turning the TV on. The second one produced the most incredible flashlighting I've ever seen; it had the "CORRUPTED UNIFORMITY ADJUSTMENT DATA" problem depicted in the Sony document at scribd.com I linked to above. The third one exhibited a "vertical blinds" effect; it was like some semi-transparent vertical blinds were superimposed on the picture, and they'd vary in intensity as the scene changed. At this point I gave up. Note that each time I put my board back in, my TV returned to my original problem, those 4 (ultimately 8, as 4 new ones have appeared) 3" flickering horizontal lines. So I don't think there was any problem with my technique or any other problem with my TV besides the TCON board.
My point is, if it really is just your TCON, I was 3/3 for getting a viewable picture, despite the three boards all having various defects that made them unusable and actually much worse than mine. So if you can't get a viewable picture after another board, it may be time to consider it's not just the TCON board.
I ordered from 3 different companies. Clearly, these companies are salvaging boards from broken TVs without testing them, and then they're selling them as functional. If it doesn't work, so what? I'm sure they paid pennies for the broken TVs, and their return rate can be way high while still allowing them to make huge profits given what they sell the parts for. Lots of the companies advertise with similar text, claiming that the boards were taken out of working TVs with a broken screen and fully tested. They are all lying. If you get one that works, consider yourself very lucky. And be wary of a lot of these companies; a single company can have several different web sites with different names. Be prepared to jump through hoops and even have to fight a bit for your refunds.