Issue adding LEDs to a 3D printer

Thread Starter

Tripp

Joined Mar 29, 2021
3
Can someone help me with an issue I am having with adding LEDs to my Ender 3 V2 printer?
The LEDs worked fine when I tested them on a breadboard with my bench power supply but after wiring them into the printer they turn off after about 40 seconds then on again 5 seconds later. Off, on, off, on all the time.

I attached a picture of my notes. I am far from knowledgeable about electronics.

The LEDs are all rated at 3.1-3.2v and 20-30ma and they are all ran in series. Using a toggle switch on the positive wire (rated 220V 6A). After the switch, I placed a 10ohm resistor (1/4W). Power comes from the printers Mean Well 350 - 24V the printer runs off of one of the 24V outputs terminals and I put my LED wires on the other terminal that was free on the PSU.

Things I have noticed so far:
The voltage before the resistor is a steady 24.17 V (never changes) voltage after the resistor is 21.2 when I turn the led switch on, then over the next 40 seconds, it climbs to 21.38 before the lights turn off. At which point the V goes up to the 24.1V and then back down to 21.2 when the LEDs turn back on a moment later.
The printer seems to be unaffected by all this and the PSU seems to always supply the 41.2V and the green light on the PSU is always lit.

Any help with this would be greatly appreciated as I have limited electrical knowledge.
 

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Thread Starter

Tripp

Joined Mar 29, 2021
3
Sorry, I realized I said it's a 10ohm resistor but it's actually a 100ohm. I just checked the current and it was 28MA then when the LEDs turn off its 0MA.
 

AlbertHall

Joined Jun 4, 2014
11,098
the PSU seems to always supply the 41.2V
Is this just mis-tryping, or where is this voltage coming from?

It seems that either one of the LEDs is faulty and goes open circuit when it gets warm. You are runnung them very close to their maximum stated current.
You could measure the individual LED voltages to find the fault location.
 

Thread Starter

Tripp

Joined Mar 29, 2021
3
Is this just mis-tryping, or where is this voltage coming from?

It seems that either one of the LEDs is faulty and goes open circuit when it gets warm. You are runnung them very close to their maximum stated current.
You could measure the individual LED voltages to find the fault location.
Yes, it is miss-typed should be 24.17 V (I don't see a way to edit the post). Thank you for your input. I will check the voltage of each LED tomorrow and lower the current.
I did try it with my benchtop power supply tonight and the issue was still present so the issue is likely something to do with what you are saying.
 
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