I have a slight yellowing in the center of my screen. We recently replaced the map, and have tried adjusting all picture settings but the yellow patch remains. It's a Sony Grand Wega, by the way.

Need to know if older set with picture tubes---turn color off--if yellow screen you have a loss of blue of some sort--red and green will give you a yellow screen. If set has the 3 picture tubes look inside in the lens to see if all 3 have a image---little or no blue means a problem there.

I hate to say it, but your Optical Block aka Light Engine is going out on you. Sony has been extending Warranty on these since they have been so problematic, but this has been on a case by case basis. Your best bet is to call Sony and keep at them. If this gets you nowhere, it will not be cost effective to fix.

Your set may have one or more of the following symptoms....

*Dull looking picture
*White looking picture
*Halos around objects
*Red/Orange looking picture

You can see some more examples and find a fix using this link on Fixya http://www.fixya.com/support/r2861467-solution_video_looking_whiteish_dull

Since you have eliminated the bulb, you must now carefully and meticulously clean the optics and lenses in front of the bulb.

I am slightly confused about the model of the television, because a 46F500 is a rear projection set that doesn't have a lamp. It has 3 picture tubes and I have a few of them in my shop right now that have the problem you reported. What we do to this set when it develops a convergence issue is to check each resistor around the convergence chips for discoloration, and replace any of them that have changed in value, along with the STK392-150 ic's. If you don't have an ohm meter and solder/desolder equiptment, you can usually get a shop to do this repair for 150.00 to 350.00. Parts will be 50.00 and labor , the rest, depending on the quality of repair shop that you use. Good luck, Russmann.

replace the focus block or try to adjust the screen control on the focus block for red only. this will affect the white balance of the set so adjust it carefully. the focus block is located on the front inside the set. remove the speaker cover then the 4 screws on the front plate. the focus block is 3" x 2" black box with 6 adjustment posts three for focus and three for screen. adjust only the affected screen (R).

I have recently developed the same yellow spot problem on my Sony KDF-E50A10  50" LCD television...a large yellow circular hue that takes up the bottom center of the picture and is especially noticeable against a white background.  It has been diagnosed as the optical block (light engine) and without an extended warranty Sony refuses to assist with the repair cost.  Repair was estimated at $1,100 plus tax and travel fees to my home.  So you see, it is not only a Hitachi problem.  You would think they could build something that would last more than two years considering the initial cost of over two grand for the TV !

1)Please verify your model # from back of set......

2)Reduce the color to minimum or tune in a black & white chan.
you should see gray, not yellow hue

3)Remove lower front grill cover & access panel.....locate the
focus / screen control block...turn blue screen control slightly
CW......red,green and blue must mix to equal gray

4) reset color to normal level.......reassemble

You might want to try the optic lens adjustment screw on the side of each crt. Mark them before moving.

most likely the yellow dot is due to a burn in the picture on the "green" lens. It's not removable because it's burned it, but you can try cleaning it because sometimes, dots are caused by dirt. The worst that can occur is that if the dot is permanant.