I wanted to give VFDs a try so I ordered a couple of 8x14 segments display modules.
They arrived today, but I'm concerned because each has a big black stain in the corner. If it were on an LCD I'd suspect they're broken, but since I don't know this display technology at all, can someone tell me:
- Are those displays broken or is the stain a normal thing?
- If this thing has a name, what is it called?
Here is a picture of the modules (the stain is on the top right corner):
Note that after checking on the seller website and a few pictures on other online resources, this kind of stain is visible on some of them, so it may be a normal thing.