Hi so I have a aluminum power circuit board (PCB) that can harness 24x 3watt leds and i have soldered correctly and made sure each led worked onto the board as you can see in the photos each single led runs as I connect them positive and negative solo but when i connect negative and positive to the actually board nothing happens but what confuses me is how there are two positive and two negatives entry point take a look at the photos please and if someone can explain what i need.

This isn't really a DIY LED forum and it's always been rather low volume; that said, maybe somebody will have an idea...


Good luck!

What voltage are you putting across the LED's?
Taking a look closely at the board the led's are in one big series circuit, so you will need a big voltage across them (ie 24x the voltage across one of them). It also means if one of the led's has a problem the whole lot will stop working.

Based on the pictures there *should* be 4 parallel rows, each with 6 diodes in series which raises the voltage some but also the amperage but that still doesn't tell me why the individual diodes work and the whole circuit doesn't. Since this isn't a DIY forum, I really don't know a lot about other requirements like the driver and PSU...

SisterMaryElephant wrote:Based on the pictures there *should* be 4 parallel rows, each with 6 diodes in series which raises the voltage some but also the amperage but that still doesn't tell me why the individual diodes work and the whole circuit doesn't. Since this isn't a DIY forum, I really don't know a lot about other requirements like the driver and PSU...

If you look closely at the picture, you will notice you can see the raised copper line under the black coating. Following that line you can see the circuit is set up as 24 in series.

As for why it does't work? There could be a number of things wrong and without knowing the whole setup i couldn't say for definite but with the information given and looking at the circuit i would say he isn't putting the correct voltage across. Biggest mistake anyone trying to DIY something who don't know anything about series or parallel circuits is to use the wrong voltage on a series circuit. They think that say an led has 2.4 volts that you put across it that that same 2.4 volts would go over all of them, but if it's 24 in series you would need 2.4x24, which would be 57.6 volts. LED's also have a minimum voltage requirement to work which in this could be for example 2v. So to even turn these LED's on and see something you would need 2x24, which is 48volts. This is assuming all the leds are the same, if there are ones which need higher voltage but lower current then you could be in some serious difficulty.

puggy wrote:

SisterMaryElephant wrote:Based on the pictures there *should* be 4 parallel rows, each with 6 diodes in series which raises the voltage some but also the amperage but that still doesn't tell me why the individual diodes work and the whole circuit doesn't. Since this isn't a DIY forum, I really don't know a lot about other requirements like the driver and PSU...

If you look closely at the picture, you will notice you can see the raised copper line under the black coating. Following that line you can see the circuit is set up as 24 in series.

As for why it does't work? There could be a number of things wrong and without knowing the whole setup i couldn't say for definite but with the information given and looking at the circuit i would say he isn't putting the correct voltage across. Biggest mistake anyone trying to DIY something who don't know anything about series or parallel circuits is to use the wrong voltage on a series circuit. They think that say an led has 2.4 volts that you put across it that that same 2.4 volts would go over all of them, but if it's 24 in series you would need 2.4x24, which would be 57.6 volts. LED's also have a minimum voltage requirement to work which in this could be for example 2v. So to even turn these LED's on and see something you would need 2x24, which is 48volts. This is assuming all the leds are the same, if there are ones which need higher voltage but lower current then you could be in some serious difficulty.

I see 4 rows of 6 (in series) although it's not clear enough for me to tell for sure if the rows are parallel or series. Series doesn't make sense for a grow light since, as you point out, if one diode dies the whole circuit is broken. Perhaps the PCB wasn't designed for a grow light though. That's why I say it "should" be series rows in parallel. All parallel would be even better.

I agree, without knowing more about the specs of the diodes, connections and the input, it's hard to diagnose.