Hdtv with purple lines

If you bought it with a credit card that usually gives you a year of extended warranty so repairs would be no cost

Hello light_tt,

Welcome, and thank you for using FixYa!

To answer your question: What you are seeing is the result of a bad video display board.
Just because we buy products new, doesn't mean they are exempt from defects. Hence why there is a warranty provided.
I recommend you use your warranty, and return this product for a replacement.

Have a great day!

If you wish to get some details; visit the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
Line faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent. Faults to all LCD & Plasma screen are similar, irrespective of its brand and screen size.
Search the site by type in the "BRAND NAME" of your device; (Exclude the model number), in the "Search box at the top right of the display window of the Homepage" to get gathered related posts...

philips tv turns itself off and on agianevery 10 mins roughly with a gap of a few mins before coming back on. only had a few months

Leave tv on and unplug it for 10 min. and plug back in should reset your tv.

I assume your Misubishi is not close to anything electrical. However, it sounds like you have had an interference for some time. This will ineviteably cause the HDTV LCD to collapse. LCD's don't respond well close to heat. Is there a vent close? LCD's do well in a properly vented area but with all this said.......they will pick up interference from anything electrical. A few questions to ask ones self........are there any wireless devices or chargers close to the LCD? Might there be an oven, a/c unit or other wiring with 220 volts anywhere close to the LCD such as in the wall?
The Mitsubishi LT is a very reliable, multi component ready set that allows great viewing with surround sound. However, stop and think about this interference. It is not something in the unit. It is an interference. Look hard and when you've discovered it.....you won't believe how crystal clear this set will be.
Let me know what you find...Thanks for using Fixya and add any comments that may help us help you.

LCD needs to be replaced.
Common problem called "Tab separation".

I would suggest to try to get this TV fix while still under warranty. Normally the manufacturers give one year.
In regards to the discoloration, there is not much you do but to let the Sony authorized repair center knows about it so they can fix it. Ask them if their work is guarantee as well for how long.
Good Luck.

Sound
Sounds like your bulb is nearing the end of its life span you will be needing a new bulb soon.