Brand new HLG 260W QB - assembled but not working :-(

Hello @George1961, @Tappy, @beacher, @ReikoX, @DatDamDog, @rooted, @santero, and all not mentioned here…

After some unexpected troubles (UPS not finding my address and the like), I finally got two brand new HLG 260 W QB s yesterday.

I wired them like explained in the video on the HLG website. The red wire goes to the brown one and on the “+” switch on the board.
The black wire goes to the blue one and to the “-” switch on the qb. Furthermore I connected plus and minus with a single wire on the opposite side.
Now see what light I get… Only a few diodes are emitting some weak light. What s wrong ? Can you help ?

it s extremely frustrating to have some new gear and not being able to use it… grrrrr…!

thank you for your time and wisdom :om_symbol:


Could be low voltage.

Is there a dimmer or dimmer input to the supply?
Power supply part number?
Additional photos of how you’ve wired this up?
Do you have a volt meter?

From the photo:

Hard to see, is that the (+) from one board to the (-) on the other board. Is this how they want you to interconnect those?

Edit: ok, I’ve watched a build video and yes, they also interconnected it that way. In series.


There is a dimmer on the driver. But this is open by default (if I m not mistaken).

Here the wiring:

…and the driver

I ve checked and double checked and back checked - the wiring is the way it must be. Period.

I can get a volt meter from my landlord…

where can I measure the output ?

Thank you very much for helping ! Appreciate very much !


Give me a moment to look up the specs.


The driver here appears to be an ELG-240-C2100. Note the slight difference in part numbers. This driver produces 2.1A at 57-115VDC. Another driver they recommend is The recommend driver is HLG-240H-C2100 with 2x QB 288 in series. That driver produces 1 Ampere at 119 - 238 VDC.

HLG-240H-C-SPEC.PDF (271.5 KB)

elg_240_c_series.pdf (301.4 KB)

Looking at the Quantum Board specs…

So, their website notes that each QB has a voltage drop of around 49VDC with a current of 2.1A. In series we just double the voltage required to obtain 2.1A and we have around 98VDC.

That “should” be fine (ELG-240-C2100), I’d think. Moreso for line voltages greater than 120.

What is your AC line voltage (>120VAC)?


thank you… :pray::pray:


See if you can borrow that volt meter. After looking at the specs, idk at the moment.

You can strip back the insulation a bit so that you can probe the voltage being applied across the LEDs. Being careful not to short anything or brush against the high voltage output, of course.

Edit: I’m also a bit confused as the “A” suffix on the supply denotes a build in current adjustment pot. That usually means it’s dimmable but there isn’t an external control input. I don’t know how they are doing the external dimming. Can you give us a snapshot of the bottom side of the supply along with the input and output wiring into it (e.g. are there three discrete cables, two, something else)?

Edit: I can see the terminals in the last photo now. So, there is no external dimming on this power supply. There is a current adjustment location on the bottom side of the supply under a rubber gasket. It is likely that will need to be adjusted as we don’t know what the factory set this to. A volt meter will be useful for that but you could try to adjust it a small amount to see if affect the intensity of the LEDs at all.


I see you found what you were looking for…

I dont think that it comes pre-dimmed from factory. This makes no sense to me… All the videos at the end of assembly, when they branch it, ALL the diodes are shining very brightliy. Cant say this of mine…

I ll get the volt meter as soon as my landlord has finished milking the cows…


Man, your way of life sounds awesome (despite the light issues)…milking the cows…holy shit…that takes me back to being 4 years old and helping my uncle on the farm in Saskatchewan!!!

Not sure if it’s available to you, but a kill-a-watt meter might help you out…you can program it so that it’ll tell you how many watts your using and give you the costs associated with said wattage. Amazon sells them for $15…it’ll tell you how many watts your light is actually pulling from the wall…


I have no idea what you re talking about. Except for this question. Here in Switzerland, Europe, we have 220 V

Now what ? Landlord still milking cows…


Good luck with this
I am watching this one this is a future project I’m looking forward to lol
Maybe I’ll Learn a few thanks
Taking notes


That black dot there is probably hiding the dimmer…marshydro has the same thing…pop that cap off and it should reveal a dimmer…small flathead screwdriver should pump up more light.


I was reviewing the specs to verify that the set-up would work together. The 220V provides you with additional margin. And, it looks fine.

Wait until your neighbor is done with the cows. Or, make a small adjustment on the current adjust. This is the next diagnostic step.


I respect your knowledge and wisdom, Tappy. But it just does not make any sense that this set was delivered with a dimmed down driver. One of our mutual friends here is growing with the same setup. He even did nt know that his driver was dimmable…

Furthermore, if the unit is dimmed down then ALL the diodes would emit a weak light. I repost the pict here how my unit looks under current.

On each board only a few led s are glowing.

Like I stated before, at the end of ALL how-to videos when they put it under current, the WHOLE board is shining very brightly. The way it supposed to be…

So what you propose, Tappy, is not the answer to this riddle…

Edit. It is a riddle indeed. All the wiring is exactly how it s supposed to be. I m still clueless…

I hate if something new is not working properly…

1 Like

It could have been moved during shipment. I would try adjusting it. If the voltage is too low, only a few of your diodes will light up. You could also try connecting just a single board. It sounds like you have low voltage. It could even be a bad connection.


With the wiring, as you’ve verified being correct, the most likely scenarios are:

  1. The IoAdj (e.g. the dimmer) is adjusted low.
  2. There is a high resistance connection somewhere (e.g. bad connection).
  3. A bad or damaged part or
  4. A bad or damaged supply.

You can verify (1) by making voltage measurements with the LED array connected. And also can try twiddling on the IoAdj. Just because someone else had a different result does not guarantee that your unit is set the same.

You can then further verify whether the supply is operating as expected (4) by measuring the voltage open circuit (LEDs disconnected).

You can further diagnose the supply (4) by measuring the current supplied with the LED array placed back in-circuit.

If the supply checks out, there is something going on with (2) or (3). Additional diagnostic steps would be needed.


Definitely get in touch with the manufacturer…


This is what I gonna do… I would have done it today but no one is in office on sundays… I ll keep you all updated…

Btw. Have I mentioned that I bought two units - and both are misbehaving ??


It s a very weak possibility… Did I mention that I bought TWO units and both of them are not working properly ?

It s quite impossible that two dimmers have moved on transport… hmmm…

It s monday tomorrow and I will contact the manufacturer/seller in Spain. Will keep you updated…

There are some good sign here with seeing some of the LEDs illuminated. This indicates that the polarity is correct, you are supplying power, and there isn’t a drastic problem with one of the components (e.g. nothing at all or flames/smoke). The most likely scenario starts with (1) as noted above.

Believe it or not, that is actually a good sign. The likelyhood of a component problem being the issue has dropped.

No one knows what it is set at from the factory. There is no guarantee and it is not address in the datasheet. One process change and here we are. Rather, it would be safer to ship units with IoAdj set to low and expecting the end-user to make the adjustment. Who knows…


Can you post a link of the website you acquired thse from…