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Update (19.3.24)

I checked the LED string with a multimeter. The + and - wire of the burned LEDs are connected, whereas the new LEDs do not have a connection between the + and - wires.

I checked the barrel jack as well, the + and - poles are not inverted.

(18.3.24)

Sadly, even with the right power supply, the LEDs still break and create fumes. I really don't understand what I'm doing wrong.

(16.3.24)

Firstly, I wanted to thank you all for your inputs. Indeed, the cause of my issue turned out to be an overcurrent. Thanks to your comments I went back to the electronics shop that sold the power supply to me, and we realized that the supply was labeled wrongly. The producer labeled the supply as 5V 4A, even though it was 15V 1.6A. This was most likely the main issue, I will try out the same setup with the correct current later and update, if it works. Thanks again for your help! :)


I'm trying to build an LED-cube using string lights and a raspberry pi 4. I followed along this tutorial, in which the RGB WS2812B strip has 5 wires going into it: two red (power) wires, one for external power and one for the raspberry pi as a power source. Then, two white (ground) wires, so the power supply and the raspberry share a common ground. Lastly, one green (data) cable.

The LEDs I ordered only have three wires, though. A power, data and ground wire. I figured that by soldering the wires, I could reach the same hardware setup like in the tutorial.

I wasn't sure how to connect the two ground cables, so I twisted them and screwed them into the barrel jack.

Wiring from tutorial

My wiring diagram

Wiring into the Raspberry Pi

Barrel Jack wiring

Connection to LEDs

I tried this setup three times, each time thinking that I did a bad job soldering or I did something wrong when powering the LEDs. Each time I only powered 10 LEDs. Keep in mind that during my attempts I did not run a single line of code one the raspberry pi.

On attempt one the LEDs blinked in irregular intervals, but slowly started to loose light. On attempt two I powered the LEDs and the Raspberry Pi at the same time, which lead to a short circuit. On attempt three I powered the LEDs first. Again, the LEDs blinked, but not all of them. As soon as the Raspberry Pi was booted, there was another short circuit. This time I noticed that one LED was particularly hot and had burned the plastic surrounding it.

enter image description here

I'm really new to all of this, so I believe that I might have done something wrong with the wiring. I ruled out the power supply, since the 5V 4A DC power supply complies with the instructions given by the tutorial and the product specification of the LED lights. I think the ground connection I did is the problem here, but again, I'm not sure. I don't understand why I cannot wire it the way I did.

The other possibility is that the LEDs are bad, but I do not have any way to know this. Can someone explain why my LEDs overheated? Great thanks!

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  • \$\begingroup\$ Have you checked (again again :-) ) that +5 and ground have not been swapped? \$\endgroup\$
    – Russell McMahon
    Commented Mar 13 at 22:00
  • \$\begingroup\$ @RussellMcMahon Hi, thanks for your reply. I lost count of how many times I've checked. The red (+5V) wire is connected to the plus pole of the barrel jack. The white (ground) wire is connected to the minus pole of the barrel jack. The red wire is also only connected to the Led lights, whereas the white wire is connected to the raspi, the barrel jack and the lights. \$\endgroup\$
    – TLB
    Commented Mar 13 at 22:50
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    \$\begingroup\$ "connected to the plus pole of the barrel jack. [...] is connected to the minus pole of the barrel jack" have you measured the terminals with a multimeter to confirm that they are labelled correctly? \$\endgroup\$
    – Attie
    Commented Mar 13 at 23:59
  • \$\begingroup\$ Concerning your barrel jack, is it the type where ground is on the outside(i.e. ring of metal) or on the inside(shrouded plug)? The SMPS in question should label which contact is ground, and which one is +5V. From the picture and descriptions, this sounds like polarity reversal(or much less likely, resistor failure i.e. overcurrent). \$\endgroup\$
    – lemon
    Commented Mar 14 at 6:13
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    \$\begingroup\$ @Attie Thanks for your help, I haven't considered that the barrel jack could be labelled incorrectly, will check! \$\endgroup\$
    – TLB
    Commented Mar 14 at 13:54

1 Answer 1

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WS2812 does not work without programming. At the moment the power is on, it may get some random pulses, which chips may interpret as data. But the result is irrelevant. Your setup looks OK. Big possibility the strip is damaged. To get 5 wires instead of 3 just +5V and -5V can be split. Also current consumption should be kept in mind. WS2812 one chip may consume 60mA at full brightness all 3 colours.

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    \$\begingroup\$ Can you clarify your "-5v" ...? \$\endgroup\$
    – Attie
    Commented Mar 13 at 23:59
  • \$\begingroup\$ @attie it is white wire In that case. In common, DC power supply output has two poles,"+" and "-". \$\endgroup\$
    – user263983
    Commented Mar 14 at 8:26
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    \$\begingroup\$ The majority of DC power supplies are positive only (e.g: +5v and 0v), and not split rail (+5v, 0v and -5v)... in this situation, + and - generally do not denote +5v and -5v (i.e: 10v potential difference), but rather +5v and 0v. Clarity here is important. \$\endgroup\$
    – Attie
    Commented Mar 14 at 12:29
  • \$\begingroup\$ @attie if you take a look at the picture with DC adapter, signs"+" and "-" can be seen. Most unipolar DC power supplies outputs marked + and -.. \$\endgroup\$
    – user263983
    Commented Mar 15 at 9:25
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    \$\begingroup\$ Correct, but that does not make it -5v! It's an abbreviation of "positive" (+) and "negative" (-) which are relative terms. \$\endgroup\$
    – Attie
    Commented Mar 15 at 13:18

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