Sony kdl-46sl140... screen split in equal 4ths until tv warms up about 20 minutes

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://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.

Your LCD panel has failed, it will be cheaper to get a new set. If I have helped you please sign my guest book

http://www.back2lifeelectronics.com/Guestbook.php

If you're sound in electronics, you can surf through and get the voltages to different terminals of the power board. If you wish to get more details, http://electronicshelponline.blogspot.com/ Pull up previous posts there, either by its left side bar, or view it in Timeslide option. It has service help details to many brand televisions.

have you checked the power board for visually swollen electrolytic capacitors?

Sounds a lot like that.

http://esupport.sony.com/US/perl/model-documents.pl?mdl=KDL46SL140

hey there it sounds like the problem is coming form your digital video board this parts run around $69.99dlls-$109.99dlls I recommend you take the part out and get the part number from the board this website has a lot of parts for your TV set

http://www.discount-merchant.com/SearchResults.asp?Search=KDL40XBR3

EITHER THE MAIN SCREEN VIDEO RIBBONS HAVE GONE FAULTY IN THE SCREEN OR THE VIDEO DRIVER BOARD IS FAULTY LOCATED CENTER TOP BACK OF SCREEN

It could be something like an ETC-inverter board, or the power board. I have the same TV with a cracked screen. Are you interested in selling yours?

Goto http://esupport.sony.com/US/perl/news-item.pl?news_id=378&template_id=1

This Sounds Like Exactly What You Need.

http://esupport.sony.com/US/perl/model-documents.pl?mdl=KDL46SL140&LOC=3