Cobs smoke

HydroRed

HydroRed

Well-Known Member
Did you just add pics? I don't remember any pics in your post before offering any insight, or I would have said your HS were the problem lol
Glad you figured it out.
 
Budies 101

Budies 101

Well-Known Member
Where is good places to buy heatsinks? I found some for the cxa3070 pin heatsink but I dont see any way to buy them lol.
 
HydroRed

HydroRed

Well-Known Member
cobkits.com has pin heat sinks of different sizes.
Heatsinkusa.com has just about any size/form of heatsink you could need as well.
 
weed-whacker

weed-whacker

Well-Known Member
robincnn

robincnn

Well-Known Member
I will have 120's in stock in 2 days. Pre drilled for 3070. Should be good for 60W

Not sure why it's smoking. I ran a cob without heatsink once and saw smoke. Smoke was from the LES phosphorus burning up. made a pop sound within few seconds and silicone phosphorus LES was damaged followed by broken diode connections and the cob went out of action.
Not sure what grade steel or aluminum you using as heatsink. Steel does not look as good as aluminum in terms of thermal conductivity. cobs have concentrated heat so proper heatsink is important. The steel should still soak up some heat... Does the steel heatsink you have heat up right behind the cob atleast ? if it does not then i think thermal interface material could be the issue or may be there is some paint or something that is blocking the heat from cob to heatsink

http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html
https://en.wikipedia.org/wiki/List_of_thermal_conductivities
 
R

Ryante55

Well-Known Member
David Abrahamson said:
Well thank you, Kingbrite sent them to me and said it would all work. I hope that's not the issue but it might be =(

Sucks seeing as I bout 56 cobs and a bunch of drivers.
Click to expand...
Damn bro that's alot to invest without doing research you need to buy yourself 56 heatsinks
 
Budies 101

Budies 101

Well-Known Member
Ryante55 said:
Damn bro that's alot to invest without doing research you need to buy yourself 56 heatsinks
Click to expand...

Well to be fair I built my first lights and it worked just fine. I did these lights different but it only cost me like 5 bucks for the case so buying heatsinks was something I always considered. I built my first lights like 8 months ago or so and knew nothing about LED's at all... I understood why you need a heatsink but as I said it seemed to work without it on my first build.
 
Budies 101

Budies 101

Well-Known Member
robincnn said:
I will have 120's in stock in 2 days. Pre drilled for 3070. Should be good for 60W

Not sure why it's smoking. I ran a cob without heatsink once and saw smoke. Smoke was from the LES phosphorus burning up. made a pop sound within few seconds and silicone phosphorus LES was damaged followed by broken diode connections and the cob went out of action.
Not sure what grade steel or aluminum you using as heatsink. Steel does not look as good as aluminum in terms of thermal conductivity. cobs have concentrated heat so proper heatsink is important. The steel should still soak up some heat... Does the steel heatsink you have heat up right behind the cob atleast ? if it does not then i think thermal interface material could be the issue or may be there is some paint or something that is blocking the heat from cob to heatsink

http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html
https://en.wikipedia.org/wiki/List_of_thermal_conductivities
Click to expand...
How much are they per?

I just bought some of the long flat fin heatsinks like what realstyles uses (dono how to spell his username). I bought 4 for veg lights that are going to be different than the flowering lights.
 
sixstring2112

sixstring2112

Well-Known Member
i would think even thin steel would be good for 10 mins before it got too hot.im still guessing it to be too much paste or a wiring issue.if you ever looked at a mars panel,some of the leds are NOT mounted on the heatsinks,they are just on a flat piece of aluminum that is very thin.probably why those lights eventually fail but still mine ran for a solid 14 months lol.
 
SPLFreak808

SPLFreak808

Well-Known Member
With diamond style paste, adding to much will pro-long the break in period. Put that on a steel post and you'll probably see smoke. Do what these guys suggest and re-apply the paste lightly
 
welight

welight

Well-Known Member
my first guess was the heatsink. While throwing lots of metal at a cob seems intuitive, the design of the heatsink and its ability to move heat through the sink is its key. The path to ambient is the rule of law with heatsinks and you need a path of least resistance which is difficult to achieve with flat bar, image below of our 140mm pin fins demonstrates what you need, an even spread of heat across all surfaces, if you can get the heat away, those babies will cook

Cheers
Mark
 
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