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LED channel control issues on the mini


Exidous

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Good morning,

 

I am having a few issues with my led fixture. It uses 12NW, 6CW and 6RB 3W Crees(fresh planted). One LDD per color channel and a MW 350w PSU. The mini is powered by a MW dc-dc converter(36-72VDC in,12VDC out).

 

When I have CH 1(NW) and 2(CW) at 100% and CH 3 (RB) at 0% 1 & 2 are nearly at 100% but not at 100% for some reason. If I raise the RB CH the other two get progressive dimmer. This can be tested and seen in free mode as well. In addition, under morning I cannot get the lights to display above roughly 30%. If I lower one of the two white channels from 100% the other gets brighter. I've noticed I can only have two channels at 100% at a time. Any two at 100% will dim the others. I have a 4th channel that will be running an algae scrubber. Not yet hooked up but the channel will dim the others as I increase it.

 

Changing the start time for morning seems to have no effect on when the LEDs turn on. They turn on around 10 and brightest at noon.

 

The other issue is that the night settings are affecting the day time settings even in the middle of the day. At 2pm I can increase the night settings and the light will get brighter. I've checked time zone and simulations.

 

I've disabled as many features as I can to figure out what is going on but am at a loss.

 

Thanks for any help you can provide,

 

Patrick

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Make sure your wiring is correct on the channels. As well check the output on the power supply. Is everything properly grounded as well?

 

-Dave

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Everything shares a common ground. The only thing I have not done is tie it to the earth ground in the wall.

 

I was a bit unsure of how to connect it. Can I just take the earth ground in the wall and tie it to the DC neg output of the MW PSU?

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Right which is why I ask. DC ground is usually just 0VDC or no voltage potential. My question is, aside from grounding the DC neg together where else can it go. The AC is tied to earth ground obviously.

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jedimasterben

Check all your solder points on the LEDs themselves. Did you use stranded or solid wire? What LDD board are you using?

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It's the LDD-H-4 board at rapid led. It has three 1000mA and one 700mA on it. It uses stranded 24ga on the strings and 20ga on the supply. I measured current on the supply and it's only about 2A max @ 42VDC. The 4th channel isn't even hooked (grow light for scrubber) up but it will still cause the other channels to dim when I move the slider.\

 

Any one string will run at 100% by itself so the solder joints per string should be fine. Plus I'm military certified on high reliability soldering. That certainly doesn't preclude me from being human but it does help. :-)

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jedimasterben

Yes, that certainly does help!! :D

 

It's so strange, the only time I've seen the weird dimming is a grounding issue, but it could possibly be a defective PCB, too.

 

Do you have any pics of how everything is wired up?

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I can get one in a few hours.

 

I should note that if I use the jumpers on the board where disconnecting the bluefish means they are on 100% all 4 will go to 100%

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jedimasterben

Interesting. I wonder if the there is some crosstalk on the PWM channels on the board itself?

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I'm pretty sure there is. I removed the 700mA LDD but left the pulldown resistor on that channel only. Now they are working properly. The odd thing is that when I touch the BF on the SD card metal casing the LEDs flicker. So obviously there is a ground issue.

post-91561-0-16189700-1465497509_thumb.jpg

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The diagram above is exactly how I have everything wired up btw. I'm thinking I need to tie the 48v and 12v grounds together. As of right now the ground reference for the pwm has to go through the dc-dc meanwell.

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jedimasterben

Yes, just run a wire between the grounds and see what happens. I think this is the issue, since the DC-DC 12v converter keeps its outputs and inputs separated.

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I'll check it tomorrow with a multimeter to see if there is any voltage differential between the two DC - first just to make sure. I'll report back what I find.

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jedimasterben

The BF Mini's DC ground needs to be connected to every DC ground (constant voltage, not the LDD constant current outputs, those are the exception :D) in the system, otherwise weird crap like you're experiencing happens. Now that I've seen the above diagram, I am 100% positive that is the issue. Report back with your findings when you can :)

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I checked the voltage difference between both negatives on the MW DC-DC PSU for the BF and there was a 0.72VCD difference. Tied the two together and the lights got fractionally brighter (set to 100% on NW & CW). Checked the RB channel and cranked it up to 100%.

 

Success!!!

post-91561-0-14305600-1465753458_thumb.jpg

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