This step is the hardest to describe. You will definitely need:
- M3 screws (I am guessing 10mm would be the right length)
- M3 washers
Because the panels you have may not be a matched set, you may also need:
- The entire contents of a hardware store
Just a little humor, as I found this step incredibly frustrating.
This picture shows how to screw the LED matrix panels to the acrylic.
My local hardware store only had very short and very long M3 screws, so as you can see in the picture, I used a large nylon spacer to make a gap. If I had ordered a bag of screws online, I would not have needed this spacer.
Start by positioning all of the panels LED side down, with the silk-screened text on the PCB normally readable, like this:
Position the panels in a 2x2 square, as close to each other as possible. Now carefully place the acrylic LED mount from the previous step over the panels. What was the upper surface of the acrylic in the laser cutter, should be touching the back of the LED matrix panels. What was the 'top' edge of the acrylic should remain the 'top' edge. Adjust the panels and the acrylic piece until as many holes as possible line up.
Not all of the holes are used for any given panel. The acrylic piece supports two different kinds of LED matrix displays. Also, some of the holes are used as alignment guides, with small plastic pins on each matrix fitting in to them to help you out.
When it looks like you've got it close, carefully start screwing the M3 screws in. Do not tighten them all the way down yet, there should be some slip in each panel. The holes in the acrylic are intentially larger than required so that the display may be aligned later.
The final display should look like this:
First attach two 4" ribbon cables between each horizontal pair, along the center line as shown above. Then take one 18" ribbon cable, and attach it from the lower-right connector to the upper-left connector. All of these connections are keyed, so the cables should only go in one way.
Attach another 18" ribbon cable to the only 'input' jack left, on the lower-left side of the display. This goes to the LED port on the Cape built several steps ago. The cape connector is not keyed, so be careful to plug the red wire in towards the top of the connector.
Last step is to hook up the power. Use the same cables from the "Smoke Test", and plug them in as before. The cables I used came with my LED matrix panels, and are shown above.
Almost there with a working display, just to align it. Repeating the smoke test should produce a working display at this point. Look to see if all rows and columns are nice and straight. Slowly tighten the screws down, adjusting the panels from time to time. Try and push them together to eliminate any gaps between each panel, and carefully rotate them if they appear out of line.