Drive ws2812b with Arduino Mega 2560 using FastLED library.

Code looks ok, wiring looks correct, if the soldering is proper then I'd start seeing if the sketch is actually uploading. Are you clicking Upload and not just clicking Verify? Sounds stupid but it has taken pages to reach that conclusion before.

Is the capacitor necessary to drive a single LED?

It is in the data sheet that each LED requires a decoupling capacitor, I have never used one without.

The orientation mark is on the corner with the black wire going to ground.

That sounds right.

The first photograph looks like the data is connected to pin 7 not 6 like the software says.

Also try using a different 5v pin, like the one actually under the "Power" label next to the gnd you're using

Grumpy_Mike: It is in the data sheet that each LED requires a decoupling capacitor, I have never used one without. That sounds right.

The first photograph looks like the data is connected to pin 7 not 6 like the software says.

OK, I'm not sure. I don't have any capacitors so I can't test that. If I can't get anything else to work I'll look into getting some. The picture may look off, but I have double checked the wiring and used a multimeter to check the voltages.

I have double checked the wiring and used a multimeter to check the voltages.

Where did you probe? You need to probe on the metal of the LED connector not on the soldered joint to make sure the joint is correctly made.

Grumpy_Mike: Where did you probe? You need to probe on the metal of the LED connector not on the soldered joint to make sure the joint is correctly made.

I tried as well as I could to contact only the pads, but there isn't much room to work with, even with fine pointed probes.

Edit: Wired another up just the same in-case of a bad chip. Still nothing. I'm going to assume its a capacitor issue then.

It is possible that soldering the LED damaged it. I would try another one with thinner wires.

Grumpy_Mike: It is possible that soldering the LED damaged it. I would try another one with thinner wires.

Maybe, I just carefully wired a new one. Still nothing. I'll add a picture in one second.

So have you tried the other 5v pin or should I just let you go off worrying about capacitors? Your clone board could simply be mislabeled as the pin could be aref with high resistance. So the least you could do is try what I said.

INTP: So have you tried the other 5v pin or should I just let you go off worrying about capacitors? Your clone board could simply be mislabeled as the pin could be aref with high resistance. So the least you could do is try what I said.

I did. I didn't respond because I am rate limited on this new account, and figured that was a pretty obvious thing.

|500x375

Alright. I tried a third LED and this one is working.... I might have a bad batch, or maybe some were damaged in shpping. I got them in a pretty wrinkly looking shipping envelope. Either way:

Thank you all for your help! I appreciate it very much.

Your soldering is indicative of an 'iron not hot enough and left on too long' so I would not be so quick to blame a bad batch of LEDs that were damaged by you.

INTP: Your soldering is indicative of an 'iron not hot enough and left on too long' so I would not be so quick to blame a bad batch of LEDs that were damaged by you.

I did damage one earlier, didn't attempt to connect it. i had the iron on for plenty of time though. it may have been poor soldering, but I tugged lightly on each one to make sure it was secure. I'll work more with the ones I may have hastily labeled bad.

jgetrost: i had the iron on for plenty of time though. it may have been poor soldering, but I tugged lightly on each one to make sure it was secure.

By on-too-long I meant you left it touching the wire and component for too long because you were waiting for solder to flow because iron was not hot enough.

Hot iron, 1-2 seconds contact, bring in solder, remove solder, remove iron.

I'm not saying the connection isn't physically attached, I'm saying the duration that you kept heating up the component damaged it internally.

A mechanical joint does not equal an electrical joint. When your iron is not hot enough flux between the wire and pad is not burnt off leaving a mechanical connection but no electrical one.

corneliain: The first photograph looks like the data is connected to pin 7 not 6 like the software

Odd I only pointed that out in reply#6

And you are both wrong because the angle is apparent and you can see the space for the header end which is an empty pin 7.

INTP: And you are both wrong because the angle is apparent and you can see the space for the header end which is an empty pin 7.

If that "you" means me then no it is not apparent otherwise I would not have said so.

Maybe not apparent if you only glanced at it on a small phone screen, but even when I did that, it was apparent. Regardless, new guy making that comment after the second pic was already up there even more apparently showing data plugged in correctly is a head scratcher.