HELP! DIY LED Issue

[addonnis242]

I have a DIY LED fixture which uses a pair of Mean well HLG-120H-48B drivers. Both drivers are currently connected to a Dual 100K potentiometer, yet one will dim down and shut off while the other will dim and stay on at what seems like 10% to 15% brightness. They were both on separate pots prior and the same issue was present.

Anyone have any idea what would cause this? I'm at my wits end with this thing.

Thanks in advance for any assistance.

 

[mcgyvr]

They really should only dim to 10% min per the datasheet.. There are always tolerances in electronics so the one that goes lower is just the "lucky" one..

To turn them off you need to switch the AC side off.. (lamp timer works just fine)

 

[addonnis242]

It just seems like there has to be something wrong. I get that there will be variations unit to unit but what amounts to a 10+% variance seems unlikely to me.

 

[addonnis242]

Ultimately I just want to turn the knob on the pot an both be at the same intensity and that's not the case until it's turned 3/4 of the way.

 

[oreo57]

Ultimately I just want to turn the knob on the pot an both be at the same intensity and that's not the case until it's turned 3/4 of the way.

If you put both on ONE 50K-0 pot this might help.. Or is that what you had at first?

Secondly do you have the same LED's on each channel?

Thirdly did you check the "dull" one for any shorts to heat sink.

Just checking a few things..
as mentioned above the one string should NOT go to zero..

http://www.meanwell.com/search/HLG-120H/HLG-120H-spec.pdf

 

[addonnis242]

Thanks for the response.

Originally I had each driver with it's own 100k pot which one would still dim to 0. Then I switched to a dual 100k pot and connected both to it. I haven't tried connecting both to a 50k pot as I didn't think that would work, I could give it a shot if it's safe to do. The LEDs are identical on each driver and I checked multiple times for shorts to the heatsink and found none.

 

[Slawdude]

I am running four of these power supplies and one does exactly the same thing ie. Only dims to 5% not entirely off.

I solved this by running it off my apex powerboard and just shutting power to the supply, which is probably good from a power usage perspective anyway.

 

[oreo57]

Thanks for the response.

Originally I had each driver with it's own 100k pot which one would still dim to 0. Then I switched to a dual 100k pot and connected both to it. I haven't tried connecting both to a 50k pot as I didn't think that would work, I could give it a shot if it's safe to do. The LEDs are identical on each driver and I checked multiple times for shorts to the heatsink and found none.

That is directly from their spec sheet..

At least that is how I read it..

 

[mcgyvr]

Ultimately I just want to turn the knob on the pot an both be at the same intensity and that's not the case until it's turned 3/4 of the way.

So stick a fixed 10k resistor in series with the one that dims all the way down..

And whats the tolerance on your pots.. I'd bet its 5 or 10%.. So right there could be the difference.

 

[addonnis242]

So stick a fixed 10k resistor in series with the one that dims all the way down..

And whats the tolerance on your pots.. I'd bet its 5 or 10%.. So right there could be the difference.

Ok so I placed a 1/2 watt 10k resistor in line and it worked out perfectly.

Thanks for the help.