E682 and a blown fuse mystery

[tonyski]

Greetings All,

I know everyone is CRAZY BUSY right now, but I’m having a pixel power issue that I can’t seem to figure out!

I’m using 12V WS2811 pixels on a wire frame. The controller is a SanDevices E682. I am using a string of 150 pixels with power coming from the controller to the beginning of the string, and power injection between pixels 50-51 and 100-101. Power is not connected to the end of the string. (See Attachment)

Using the E682 test functions, Red, Green, and Blue all work properly, but when I use pixel editor to make them all white, the 5A controller fuse blows after a couple of minutes.

I just don’t understand why that would happen, with power being applied at 3 points. My rough calculations say that 150 pixels would draw 6+ amps so I see why the fuse would blow if the controller was the only power source, but not with power being applied at 3 points. Seems as if the load should be divided by 3!

Whatever I am doing wrong, I’m doing it consistently because the second set of 150 pixels is doing the same thing!

I’m pretty sure that I could get it working with a slightly different power setup or a higher amperage fuse, (the E682 manual says that that might be necessary) but I would really like to understand what is going on.

I welcome your comments.

 

All the best,

Tony

[tonyski]

Well do you remember the old saying:

 

Nothing Good Happens After 2 A.M.

 

In my case last night, it was 1130 pm.

 

I gave Jim, at SanDevices a call this morning. As many of you have said, he was extremely knowledgeable and helpful. He confirmed that my power injection scheme was appropriate, and that the current draw should be roughly the same on all three power injection points. But then he asked a great question. “How did you notice that the fuse blew?”

 

Theoretically, with the power injection plan that I had, even if the controller stopped providing power, it still provides data. The power injection should have been more than enough to light the lights, even with no power from the controller. He assumed that for some reason, the power injection wasn’t working.

 

That thinking sort of jived with what I had been thinking so I went back to it, plugged it the power, started to investigate the power injection, and noticed this:

 

 

I hadn’t plugged the damn thing together!

 

Mystery Solved!

 

Hope my foolish error keeps some of you from making a similar mistake!

[k6ccc]

You mean it works better when it's actually plugged in? Who would have think it???

Glad you got it figured out.