LED Project Update

Wellll I have the goods all figured out now on gamma correction and LED drive levels so that it closely replicates a CRT-like response curve. This means that my test palettes look pretty much like they do on the PC. I have obtained 13 of these boards in total, and soon I will be putting them on a table saw to carefully remove about 3mm from the edges so that the boards can be tiled.

I tested the saw on 4 boards and it works very well. The boards continue to function after their ordeal and the boards fit together properly so that they can be tiled to make one super array without any gaps… at least in the Y direction. I will have to make a special cutting jig to do the cuts in the X direction, since the boards are so oblong. I will get a piece of wood or plastic and square the end, then screw the board to it and use this as a cutting guide. The cut has to be very precise so I do not saw through anything I want to keep.

Fortunately, the board is designed so that all the “stuff” is UNDER the LED array completely, so cutting the useless edges off does not impact anything at all. The two ends where a route can be seen inside the board is no trouble, it’s just a ground to the mounting holes. I will cut off one set of mounting holes so that the boards will tile properly on the Y direction.

After all 13 boards are properly cut and still work, I will then proceed with designing the system controller board. No sense wasting money on that if I screw the boards up.

Speaking of that, one of the 13 boards I have is really screwed up. About 100 of the LEDs don’t work right, and some of the driver lines are shorted. I will have to do some surgery on it if I hope to make that one work properly.

On two of the boards, the 5V and 3.3V drivers are shorted together on the output of the FETs, so I fixed that by lifting the 3.3V driver input.. This puts 5V on one row worth of red and green, but it doesn’t affect anything. The drivers get a tiny bit hotter is all, but since it’s constant current no other troubles arise.

Four of the boards have from 1 to 3 LEDs that don’t work either, but pressing on the LEDs causes them to light so the fix there is to put a little solder paste on and reflow it and those will be fixed.

So that’s the status on that project. Here’s a video of the thinger in action!