Why did my led fry?

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g-bo

Active Member
Hi folks,
I've attached a picture that shows how I wired a cree CXA3070 to a 1500mA driver with a voltage forward of 20-39v.The cree itself requires a 38.5 fv so I'm quite sure that the driver and led are matched.This is my second light the first one seems fine(maybe the driver runs a little hot but couldn't say for sure as I am not experienced enough to know)but it is working ok.When I fired up the second light it started to smoke and I shut it down as quick as could,too late tho' I think,the ceramic plate the cob is mounted on is split in half.Only the front cob surface holding it together actually.Anyways I don't really care to duplicate this experience so I'm wondering what I'm doing wrong?Am I missing something in my wiring?Maybe my heatsinks are supposed to be grounded too?Only difference in my 2 lights is the drivers(specs are the same just different makes)They are both cheap e-bay drivers maybe that wasn't a good choice. lol.Would appreciate if anybody could point out if I'm doing something wrong.I've looked at quite a few threads but can't seem to find an answer as most of them get to technical for my pea-brain.Thanks.
 

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JorgeGonzales

JorgeGonzales

Well-Known Member
g-bo said:
Hi folks,
I've attached a picture that shows how I wired a cree CXA3070 to a 1500mA driver with a voltage forward of 20-39v.The cree itself requires a 38.5 fv so I'm quite sure that the driver and led are matched.This is my second light the first one seems fine(maybe the driver runs a little hot but couldn't say for sure as I am not experienced enough to know)but it is working ok.When I fired up the second light it started to smoke and I shut it down as quick as could,too late tho' I think,the ceramic plate the cob is mounted on is split in half.Only the front cob surface holding it together actually.Anyways I don't really care to duplicate this experience so I'm wondering what I'm doing wrong?Am I missing something in my wiring?Maybe my heatsinks are supposed to be grounded too?Only difference in my 2 lights is the drivers(specs are the same just different makes)They are both cheap e-bay drivers maybe that wasn't a good choice. lol.Would appreciate if anybody could point out if I'm doing something wrong.I've looked at quite a few threads but can't seem to find an answer as most of them get to technical for my pea-brain.Thanks.
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Well 38.5*1500ma is about 58W on a 50W driver, so I wouldn't be so sure they are matched.

When power supplies fail, it can be in spectacularly bad ways. And I bet your $10 no-name special did exactly that. Next time buy Meanwell.
 
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g-bo

Active Member
Here's a couple shots of the "fried egg".
Hey Jorge you're likely right.I was under the assumption that as long as the driver was rated over what your led needed then you would be fine.Am I missing something here?The driver is rated 20-39v and the led needs 38.5 is that cutting it too close?
 

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Airwalker16

Airwalker16

Well-Known Member
g-bo said:
Here's a couple shots of the "fried egg".
Hey Jorge you're likely right.I was under the assumption that as long as the driver was rated over what your led needed then you would be fine.Am I missing something here?The driver is rated 20-39v and the led needs 38.5 is that cutting it too close?
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I cracked one once from the chip lok holder being on wrong when I tightened it down.
 
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g-bo

Active Member
Airwalker16 said:
I cracked one once from the chip lok holder being on wrong when I tightened it down.
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Yeah ,I hear ya airwalker16,really sucks losing one like that (no good way I guess).
Maybe you could answer my original question as you've obviously built you're own.
I attached a diagram of the way I wired my led....does it look right to you?Thanks man,Cheers.
 

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loftygoals

loftygoals

Well-Known Member
I have had a cheap COB come loose and fall off it's heatsink, dangling in the air while powered on for a couple hours and it still lived to tell the tale.

Could you have got the + and - on the COB mixed up? I don't know whether they have reverse polarity protection?

That driver looks ok from the label on it. CXA3070 can handle 38.5V @ 2.8A max.
 
Airwalker16

Airwalker16

Well-Known Member
Your wiring looks fine but that's a drawing. If you're SURE that's how it is on the light itself, then its right.
 
JorgeGonzales

JorgeGonzales

Well-Known Member
g-bo said:
Yeah ,I hear ya airwalker16,really sucks losing one like that (no good way I guess).
Maybe you could answer my original question as you've obviously built you're own.
I attached a diagram of the way I wired my led....does it look right to you?Thanks man,Cheers.
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The wiring is fine in the drawing, which is why I didn't mention it. I'm not really sure how you could have done that to your cob by miswiring anyway.
 
G

g-bo

Active Member
Thanks for the help men,So I'm thinking it's narrowed down to a bad led or a bad driver?
I'm gonna go with the driver since it's a piece cheap e-bay junk.If there's no way to check a driver cept plug it in and cross your fingers that's kinda shitty.Next time I plug one in I'll be ready to pull that puppy out at the first sing of trouble.lol.
 
JorgeGonzales

JorgeGonzales

Well-Known Member
loftygoals said:
I have had a cheap COB come loose and fall off it's heatsink, dangling in the air while powered on for a couple hours and it still lived to tell the tale.

Could you have got the + and - on the COB mixed up? I don't know whether they have reverse polarity protection?

That driver looks ok from the label on it. CXA3070 can handle 38.5V @ 2.8A max.
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No reverse polarity protection. I would laugh if it made cobs explode.
 
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g-bo

Active Member
Hey all,I have to update this as I finally got to the bottom of everything.I only showed one fried led but there was actually 2 of them.the other one looks just as bad as the one I posted a picture of and the ceramic the light was on was cracked in half just like the other one.I took one of my good led's and used it to check both the drivers that I had blamed for frying my led's.Turns out they both work fine sooooooooooo I have to believe that I wired the pos and neg wrong on the led itself.Can't believe I..........well yeah I guess I can.Will be slowing down and checking all connections before I fire up a light again.
Saved the best for last....the second led is actually ok and working fine.I would have never believed it if I didn't see it myself.I was sure that one f'd.So all in all I dodged a bullet for sure ...thought I was looking at 2 new drivers and 2 led's and turns out both drivers and one led are fine so I can live with that.3 out of 4 ain't bad.:).
 
loftygoals

loftygoals

Well-Known Member
g-bo said:
Hey all,I have to update this as I finally got to the bottom of everything.I only showed one fried led but there was actually 2 of them.the other one looks just as bad as the one I posted a picture of and the ceramic the light was on was cracked in half just like the other one.I took one of my good led's and used it to check both the drivers that I had blamed for frying my led's.Turns out they both work fine sooooooooooo I have to believe that I wired the pos and neg wrong on the led itself.Can't believe I..........well yeah I guess I can.Will be slowing down and checking all connections before I fire up a light again.
Saved the best for last....the second led is actually ok and working fine.I would have never believed it if I didn't see it myself.I was sure that one f'd.So all in all I dodged a bullet for sure ...thought I was looking at 2 new drivers and 2 led's and turns out both drivers and one led are fine so I can live with that.3 out of 4 ain't bad.:).
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My tip for wiring up COBs is to do it systematically if at all possible. Mount all your LEDs at the same time pointing in the same direction. Cut and strip your + wiring. Solder all your + wiring. Cut and strip all your - wiring. Solder all your - wiring. That way things seem to go a lot smoother IMO. It saves you thinking back and forwards between different things all the time. It can all seem so easy at times that you can overlook simple things and end up making mistakes.
 
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g-bo

Active Member
loftygoals said:
My tip for wiring up COBs is to do it systematically if at all possible. Mount all your LEDs at the same time pointing in the same direction. Cut and strip your + wiring. Solder all your + wiring. Cut and strip all your - wiring. Solder all your - wiring. That way things seem to go a lot smoother IMO. It saves you thinking back and forwards between different things all the time. It can all seem so easy at times that you can overlook simple things and end up making mistakes.
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Roger that Lofty Goals,sage advice there.Gotta say tho just to see how much abuse one of them cobs could take it was almost worth it...almost lol.
When the last light is in and I get the time I think I may start a post with the most basic instructions possible on how I put it together.I hear too many people saying they have been gathering information for months from the threads and are almost ready to try a diy led.Suppose everyone has different size grows and needs but that's the beauty of led's you could learn to make one then add what ya need.For me if I would have found a parts list and BASIC instructions to put it together I think I could have gotten here sooner.I think you could go as deep into the research as you wanted later but just to "get er done" ....you know.Anyways rambling away here......so thanks for all the info and good advice.Awesome forum,Cheers.
 
JavaCo

JavaCo

Well-Known Member
If you hook a LED up backwards It turns it into a light sensor. The led will act like a switch , When light hits it ,it closes and lets voltage and current thru. If it is in the dark it will open or be off.
 
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