First the bad news
The yellow stain on my 70" XBR2 has returned. You might recall that I
reported in August about my *first* optical block (OB) replacement. The yellow stain on the original OB was very subtle compared to the problems that I had seen on XBR1 SXRD's, but it was noticeable under most circumstances so I had the OB replaced.
After the OB replacement the new OB looked great, at first. About late September/early October I began noticing a large yellow stain on the right side of the screen on startup that would disappear completely after 15-30 minutes warm-up. By ~early November I began noticing a curvilinear yellow band on the far right side of the screen that did
not disappear completely after warm-up. This band is far enough to the right that it does not appear on 4:3 programming, and it is only really noticeable on light blue/gray/green backgrounds. If a white background is bright enough, I don't see it. There is also a persistent very faint yellow discoloration extending from the band across the middle of the screen that is only rarely noticeable after warm-up.
The band and discoloration are faint enough that I couldn't reliably photograph the problem for you, and most people wouldn't notice it if they weren't looking for it, so I considered it unfortunate, but acceptable for now- but it
is there. Other than the yellow stain, my current OB is phenomenal. ("Other than
that Mrs. Lincoln, how was the play?") I know that the problem will likely worsen over time and I will eventually have to have the OB replaced (and who knows, I might get a "perfect" OB next time), but the picture is OK for now and I'm concerned about having the OB replaced so often that Sony gives up and just refunds the purchase price rather than fix the problem. The fan is now set to its high altitude setting (I didn't notice any increase in fan noise at that setting) and the lamp is set to power-saving in an attempt to keep the OB cooler and delay the progression of the staining- thinking that the yellow staining is a heat related problem. I really like this display- despite the problems- and I'm hoping to nurse it along until there's an acceptable 70"+ replacement.
Now the good news
Jeff Meier/umr from
AccuCal came by yesterday for a "home theater" calibration ("family room" calibration, really

). I had him come despite knowing about the yellow stain in the hopes that he could improve the problem and make the rest of the display better. I also really wanted his audio calibration for my system.
Upon seeing the stain on a solid light gray background, he questioned whether a calibration would be worthwhile and gave me the option of cancelling. After discussing our thoughts on it and deciding to proceed, he checked the current settings/color and found that the necessary calibration changes would only serve to
improve the yellow staining and make it less noticeable. (Apparently sometimes the necessary changes can
increase the yellow/green color of a stain.)
Jeff of course made multiple changes to settings and made big improvements. I thought that the picture was good before he came, but now the yellow stain is indeed less noticeable and the colors across the board are more realistic. Despite being more realistic, the colors (and picture as a whole) have more "pop" with the brightness, gray scale, and other adjustments and there is a less washed-out more 3D look to the screen. If I didn't misunderstand, he said that despite the yellow stain my display had as good a gamma as
any display he had seen when he was finished.
The audio calibration was just as worthwhile. I don't have anywhere near a high-end system (but it's not an inexpensive home-theater-in-a-box either) and the sound is clearly improved now. I don't have an educated ear, but I was particularly pleased with how he seemed to improve the clarity from the center channel speaker and
really improved bass management.
I would certainly recommend a umr calibration. I'm thinking that if/when my OB continues to deteriorate and is replaced *again*, I'll have him come back on his
next tour to adjust it.
Hope my experience helps someone.