Where can i find a repair manual for 50v720 hitachi tv

Page 56 to 59 of the manual. It is accessed from the front left access panel. You need a philips screwdriver.

https://usermanual.wiki/Hitachi/50V720.1133235516

Videos as well

https://www.google.com/search?q=change+bulb+50v720+hitachi+tv

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It will be difficult to get. Anyway, contact the authorized service center for Hitachi. Gopakumar Gopalan Google

Hello, I'm sorry to tell you that that set has a bad optical assembly. The blue part has gone bad and cause's either a yellowing of the screen or blue spotting or both. You can purchase a new lcd tv cheaper than you can repair that one. Do not replace the lamp, it's not what's wrong with it, and you'll just waist your money. thanks, Terry

Sounds like fan alarm problems

Depends on the sequence. Check this manual. (if the screen is true black - it might be your lamp)

http://www.hdtvreview.com/pdf/hitachi-50v720-manual.pdf

Regarding your modle number, you tv part number is UX21517, so here's a video and picture guide of how to replace it.. .
http://guides.fixyourdlp.com/hitachi/UX21517.php

bad optical block/ engine

Check this link for the user manual it has the steps on how to replace the lamp hopefully that will be the needed information that you're looking for http://www.hdtvsolutions.com/pdf/50V720.pdf

Hope that helps...........

The light engine will need to be replaced. Without a warranty the part is very costly. You are lucky...

Light engine is going bad. I had the same problem.