Still wondering what PCB you are using. Did you have some made for the 81 LEDs?
Sorry for the incompleteness of the last post, I realize I only answered one question... I'm currently traveling (family visit to granny's in Toronto) and I was busy getting ready. Some pics when I get back.
I made new PCBs, yes. 3pcb was not only willing to make PCBs only 1.8mm wide as a standard request, they even did a pretty good job. At least, the the strips they made me were nicer than many of the Chinese strips I've bought with kits. They were ~ .80 apeice at quantity 100, and I made them trim-to-length like the other manufacturers, so I can also make strips for larger screens if I want.
The LEDs have captive/hidden pads on the bottom, and I've packed so that they're mostly touching, so the entire soldering job is a hidden assembly. I place the paste, then the LEDs on the paste using tweezers under a microscope, then preheat and reflow on a cheap but really quite decent Chinese hotplate. I milled a custom placement placement/soldering jig for the place/solder steps and have it all very nicely dialed in now. It takes me about half an hour to make one strip by hand start-to-finish, which is actually a good bit faster than I was managing before. The process thus far has been entirely reliable now that I've practiced a bit.
The price of those LEDs for small numbers is not so great. I was thinking of maybe trying to put them on the strips from creatall (with the horrible, unusable yellow-green LEDs). Better colors would be very welcome.
Although that would not solve the pattern problem I have in one of my SXGA+. But building a strip with 81 LEDs is simply impossible for me, and most likely for everyone else still using the X61.
These Nichia LEDs are a good 10x more expensive than just about anything else I've seen. I bought a reel of 5000, which is more than I have a personal need for, so I had planned to make up a bunch of strips and sell them at cost. But first I need to figure out the last of the placement riddle.
Conceptually, it's not hard-- the easiest approach needs an air gap of about .5-1mm between the strip and the waveguide to make the pattern disappear. A clear spacer strip doesn't work the same, it preserves the reflections. So I've been playing with accordion folds, punching, or heat molding a strip that will enforce the air gap without taking up the entire space itself.
It also occurred to me that I could probably laser-cut a clear spacer strip in a pattern to counteract the unwanted pattern with a new pattern that could cancel it out.
Yes. I already made measurements actually, but the final placement and fitting will affect the results, so those were just to get a starting point.