LED Build Issues!

Yodeling

Yodeling

Premium Member
Yesterday, I had some issues with the 12v step-down started turning on and off randomly, so I plugged the Arduino and fans into a wall wart for now.

Today, I noticed the lights flickering at about 50%, so I started playing with the settings and discovered that the lights won't all run at full power. When I start turning up one channel, the others start dimming and vice versa and everything turns off eventually.

Here are some details:
- The power supply is a chinese-made 360W 48V.
- I'm running Coralux 5up LDD boards and six LDD (700mA and 1A) drivers total.
- I calculated the power requirement of all LEDs to be about 205W total.

What I've done:
- I've checked the output from each driver individually at full power. Highest was 44V.
- The PS is providing about 48.4V (I've adjusted it down from 56V).
- When turning up the LEDs, the current measures 3.7A before everything shuts off.

Question is, could this be anything other than a faulty power supply? It should be capable of 5.7 Amps. I've never seen a PS that was not providing the rated power. It either works perfectly or dies.

Any help appreciated!!
 
That's some weird behavior all right. My guess, a you already suspect, it's the power supply. I had a similar problem with a cheap chinese "Meanwell knockoff" last year. Should have known when the supplies manufacturer name was MENGWELL.
 
Yodeling said:
Yesterday, I had some issues with the 12v step-down started turning on and off randomly, so I plugged the Arduino and fans into a wall wart for now.

Today, I noticed the lights flickering at about 50%, so I started playing with the settings and discovered that the lights won't all run at full power. When I start turning up one channel, the others start dimming and vice versa and everything turns off eventually.

Here are some details:
- The power supply is a chinese-made 360W 48V.
- I'm running Coralux 5up LDD boards and six LDD (700mA and 1A) drivers total.
- I calculated the power requirement of all LEDs to be about 205W total.

What I've done:
- I've checked the output from each driver individually at full power. Highest was 44V.
- The PS is providing about 48.4V (I've adjusted it down from 56V).
- When turning up the LEDs, the current measures 3.7A before everything shuts off.

Question is, could this be anything other than a faulty power supply? It should be capable of 5.7 Amps. I've never seen a PS that was not providing the rated power. It either works perfectly or dies.

Any help appreciated!!
Click to expand...

How many LED's are you using, and how are they connected to the drivers?
 
gbru316 said:
How many LED's are you using, and how are they connected to the drivers?
Click to expand...

The Coralux boards provide the connections. The power goes into the first board, then the second is connected to the first via the extra voltage terminals. The common ground is also used by the Arduino and the fans (not sure why fans but shouldn't hurt). The Arduino is running customized Typhon code (to run 5 channels). PWM comes from the Arduino to the PWM terminals on both boards.

Here's the config:

5Up board #1
============================
1) 700H - Luxeon K16 RB @ 45v -> 31.5W
2) 700H - Vero 10 @ 28v -> 19.6W
3) 1000H - 4x Rebel 3ups (Lime) @ 36v -> 36W

5Up board #2
============================
1) 700H - Luxeon K16 RB @ 45v -> 31.5W
2) 700H - Vero 10 @ 28v -> 19.6W
6) 1000H - 4x Rebel 3ups (Blue/Cyan) @ 38v -> 38W
7) 700H - 4x LedGB @ 40v -> 28W

Total comes up to about 205W.

Btw, the above is actual measured voltage at full power (measured for each LDD), and slightly higher than theoretical specs in almost all cases.
 
Just to completely rule out the arduino, disconnect it and short the pulldown resistors. This should cause the LEDs to be driven at 100%. If 1 channel works fine, add another channel. Add another if 2 channels work. Keep doing so until you run into problems.

If you experience the same thing as you originally experienced, the problem is the power supply. If not, it's something with the arduino.
 
gbru316 said:
Just to completely rule out the arduino, disconnect it and short the pulldown resistors. This should cause the LEDs to be driven at 100%. If 1 channel works fine, add another channel. Add another if 2 channels work. Keep doing so until you run into problems.

If you experience the same thing as you originally experienced, the problem is the power supply. If not, it's something with the arduino.
Click to expand...

Very cool idea! Question though, do I need to disconnect the PWM inputs before I short the resistors, or can I leave them in? I'd rougher not touch the mess of wires.
 
Ok I tried it and the power supply is fine. The arduino wiring was the issue. I believe what happened was that after I replaced the faulty step-down with a wall-wart, I neglected to tie the grounds properly. Which makes me wonder how it worked at all. Maybe it was using some of the PWM pins to sink the current? Anyway, thanks for your help!
 
If arduino wall wart was not tied into the PSU/LDD ground then I'm sort of surprised anything lit up at all. That was your issue, glad you got it sorted, always frustrating when things don't work and you realize it was a tiny little oversight on your part :)
 
Yeah I'm glad as well, though it will bug me that I have no idea how it was working. Also, I wanted to mention that shorting the resistor did not work. I had remove the LDDs and run them with the PWM open. I am not 100% sure, but I believe the resistor is there to sink the PWM pin to ground, so shorting it has no effect. I think if I removed the resistor, it would work.
 
gbru316 said:
Oops yeah, you're right.... That's what happens when you're on the tail end of a 14 hour shift.
Click to expand...

FYI for future reference a 5 volt wall wart can be used for testing purposes to provide a full on signal to the LDDs via that boards pwm pin but you would want to disconnect the arduino to do that.
 
zachts said:
FYI for future reference a 5 volt wall wart can be used for testing purposes to provide a full on signal to the LDDs via that boards pwm pin but you would want to disconnect the arduino to do that.
Click to expand...

There are many ways to skin a cat :fish1:
 
zachts said:
FYI for future reference a 5 volt wall wart can be used for testing purposes to provide a full on signal to the LDDs via that boards pwm pin but you would want to disconnect the arduino to do that.
Click to expand...

Yeah I was wondering about that. My method was easier in my case since I could leave all wiring in place and I used some headers to raise the LDDs up and only connect the 4 leads. But this may prove useful at some point. It would be useful to have a switch or a jumper on the Coralux board to break the trace containing the resistor.
 
Yodeling said:
Yeah I was wondering about that. My method was easier in my case since I could leave all wiring in place and I used some headers to raise the LDDs up and only connect the 4 leads. But this may prove useful at some point. It would be useful to have a switch or a jumper on the Coralux board to break the trace containing the resistor.
Click to expand...

RapidLED's board now has those built into it. As does the later versions that O2surplus designed on another thread.
 
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