DIY LED panel not working properly, need advice.

I finally got my PCB and 3w leds for it, soldered them on, connected the driver, plugged it in and not much happened. They barely lit up. I checked the voltage from the driver to the board and every thing was fine. I also noticed that when i touched the edge of the pcb they light up a slight bit more but still no where near what it is suppose to be. Does anyone have any ideas.

Just curious, but how many LEDs, and why a PCB instead of mounting them to a heat sink?

brotherjericho said:

Just curious, but how many LEDs, and why a PCB instead of mounting them to a heat sink?

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Im running 24 x 3w leds. I went for a pcb because it is neater and im not using a heat sink, im just going to mount a 120mm pc fan to the back of it.

Maybe someone else can chime in, I'm still a noob to LED, but that many 3w LEDs on a pcb sounds like a recipe for thermal disaster.

A nice little reference: http://www.philipslumileds.com/uploads/232/AB05-pdf

Do you have a multimeter?

Sounds to me like the thermal slug might not be isolated or sometihng like that. If you have a multimeter (which you should as they cost pennies and are hella useful) you can do some diagnostics.

I run 24x 1W led pcbs bare with 120mm fan only, 24x 3w may be too hot as brotherjericho mentioned. That said, it wouldn't be what is causing you the problem at hand. What are the specs on the driver? did you test the LEDs individually with some AA batteries?

caretak3r said:

I run 24x 1W led pcbs bare with 120mm fan only, 24x 3w may be too hot as brotherjericho mentioned. That said, it wouldn't be what is causing you the problem at hand. What are the specs on the driver? did you test the LEDs individually with some AA batteries?

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No i havent tested the leds yet, ill give that a go. As for the heat issues, i already have a 50w ufo (25x3w) and that only runs a tiny 80mm fan and its not even warm to the touch. Im hoping to run a similar setup to that but if i find it is running too hot i can get a heatsink like on the astir grow lights. I bought the same pcb from Merry so i definately think its either my bad soldering or maybe a couple of dodgy chinese leds. I got my leds for about $3 for 10 so you can only imagine how good they are. I re-ordered another pcb from Merry and decided to get her to supply and solder the leds on for me so hopefully no more problems but it would be nice to know what i have done so i can learn for next time.

The specs of the driver are output voltage is 50-100v, 630mA current

The 'Snot brother' is onto it....i had troubles without a multimeter to isolate the problem......

There is alwayz the 'Franjan'...get a foil pie plate (not sure what they are called) mount the PCB on that, with the fan on the back....it also doubles as a reflector...

jimjim2609 said:

The specs of the driver are output voltage is 50-100v, 630mA current

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So I take it from this info that you need a minimum of 50V forward. Do you have that?

So i checked the polarity of the leds with a couple of AA batteries joined together and it would appear the + and - do not always mean + and -. I went through and found several of the beads labelled incorrectly. Not all of them just some. Even the same colored beads are not all the same. Some were correct but alot werent. Ill fix that up and it should sort the problem. Thanks for everybody's help

do be careful 3w leds will melt down if they cant dissipate the heat
i have a few to prove it

24 x 3W = 72W
50V x 630mA = 31.5W

I don't think Your power supply is going to be up to it.

Even assuming it can supply the full current at 100V, that's only 63W

Here are some photos of how the light looks. I mounted a heatsink to the back of the pcb and with a fan on it constantly it should be enough cooling. I think it is better to under run the panel a little bit so not to shorten the life of the leds. I also have another ufo running as well so 2 in that space plus 2 x 10w red:blue spotlights is a good amount of light for my budget.