Fried Egg

tightpockt

tightpockt

Well-Known Member
Not sure what happened. It got so hot it baked the surface layer, melted the solder on the - solder point, and after just touching it, it flaked off showing a burnt bottom and heat sink. I inspected by touching the heatsink and pad and it had the worst smell ever, I can't even describe it, so bad I thought it could be toxic and started getting all paranoid.....it lingered on my finger for like 5 hours (insert joke here)
Here's some pics. This was the very first light I made a few months back, I'm sure I fucked up somehow.
cob1.jpg cob.jpg
 
The Dawg

The Dawg

Well-Known Member
tightpockt said:
Not sure what happened. It got so hot it baked the surface layer, melted the solder on the - solder point, and after just touching it, it flaked off showing a burnt bottom and heat sink. I inspected by touching the heatsink and pad and it had the worst smell ever, I can't even describe it, so bad I thought it could be toxic and started getting all paranoid.....it lingered on my finger for like 5 hours I Boogied In Da Kitchen I Boogied In Da Hall I Got some On my Finger So I Wiped it On da Wall :hump:
Here's some pics. This was the very first light I made a few months back, I'm sure I fucked up somehow.
View attachment 3435486 View attachment 3435487
Click to expand...
 
tightpockt

tightpockt

Well-Known Member
I should also mention that I think I'm way under running the fans, 6v @ 300ma split between three fans...that was probably pretty dumb
 
mc130p

mc130p

Well-Known Member
did you use thermal adhesive to adhere them to the heatsink? I used arctic silver thermal compound with the holders, no problems so far.
tightpockt said:
I should also mention that I think I'm way under running the fans, 6v @ 300ma split between three fans...that was probably pretty dumb
Click to expand...
i don't think the fan would have helped. it looks like you had poor heat transfer to the sink.
 
bicit

bicit

Well-Known Member
tightpockt said:
I should also mention that I think I'm way under running the fans, 6v @ 300ma split between three fans...that was probably pretty dumb
Click to expand...
I have a 5v 450ma driver(cell phone charger) for 6 fans, never been an issue. I'm just going to guess that the tape came off a bit and the cob slowly separated.
 
SupraSPL

SupraSPL

Well-Known Member
Were your fans wired in parallel so they each get 6V? What type of thermal compound was that. It looks like you applied the thermal compound correctly but it seems to have broke down over time?
 
tightpockt

tightpockt

Well-Known Member
SupraSPL said:
Were your fans wired in parallel so they each get 6V? What type of thermal compound was that. It looks like you applied the thermal compound correctly but it seems to have broke down over time?
Click to expand...
I used the 2 part arctic silver thermal adhesive and I *thought* I applied it pretty good.... for the fans I just connected all the black wires together and all the red wires together. Maybe there were imperfections in the heat sink that caused a bad connection, maybe it wasn't perfectly flat? I don't know, I'm just brainstorming but I know it got hot enough to melt the solder and crack the surface layer. Although it still fired up when I connected everything back together I didn't trust it and I trashed the COB
 
Abiqua

Abiqua

Well-Known Member
tightpockt said:
I used the 2 part arctic silver thermal adhesive and I *thought* I applied it pretty good.... for the fans I just connected all the black wires together and all the red wires together. Maybe there were imperfections in the heat sink that caused a bad connection, maybe it wasn't perfectly flat? I don't know, I'm just brainstorming but I know it got hot enough to melt the solder and crack the surface layer. Although it still fired up when I connected everything back together I didn't trust it and I trashed the COB
Click to expand...
2 part? are you sure it wasn't epoxy, heated too much?

PK3 is usually cheaper than Arctic anything and according to data specs, superior.....I recommend it....
 
tightpockt

tightpockt

Well-Known Member
stardustsailor

stardustsailor

Well-Known Member
well...

My personal experience and testing with the CXA series has shown me,
that although they are probably the most efficient COBs around ,when it comes to their relation with heat,
these "eggs" aren't the best deal ...
No matter what some other people and/or forum members have to say about it ,
myself I've already seen their "bad " behaviour regarding heat transfer .
Even the dedicated holders from Ideal ,can not assure a good contact with the heatsink ...
As expected ,sort of speaking ...
Nothin' is perfect ...
CXAs / CXBs included ...
In fact they have quite "faulty" design ,for heat transferring .
Tightly packed dies ,epoxy glued dies on ceramic substrate ,the ceramic substrate itself ,
thin layer of optic silicone (in order for less light losses ,but quite prone to thermal deterioration ) and few more design faults ...
You just can't have it all ...You gain here ,you lose there ...
That's how things work everywhere in the whole universe
Long live the Veros...( Literally speaking ...)

Bet you that in the months to come ,more and more of such cases / issues(regarding CXA/CXB s) are going to pop-up .

Disclaimer : That is only a personal view ,although based in true facts and testing outcomes.
So...Better take it with a grain of ...pepper ...:fire:

Cheers.
:peace:
 
Abiqua

Abiqua

Well-Known Member
tightpockt said:
Yeah, I guess epoxy is what I meant vs. adhesive...I'm using this with the COBS in the holders

http://www.amazon.com/Antec-Diamond-Thermal-Compound-Formula/dp/B004AGXHDC

Mostly because that's what was in stock at best buy and I couldn't wait for shipping.
Click to expand...

Well I am curious of what actually happened....forgive the un-intentional pun, but on the surface, it looks like it was fried without thermal backing...some kind of interference...but I am just going over types of possibilities...:peace:
 
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salmonetin

salmonetin

Well-Known Member
...you check the driver outputs? volt and amps.... maybe the problem its a fail on driver output... (and a bad driver protections too)...

...for my pov the cobs needs a temp control... ...on high temps... off the drivers...

....or dimm driver down.... and if the high temp continues... off the driver...

saludos
 
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tightpockt

tightpockt

Well-Known Member
salmonetin said:
...you check the driver outputs? volt and amps.... maybe the problem its a fail on driver output... (and a bad driver protections too)...

...for my pov the cobs needs a temp control... ...on high temps... off the drivers...

....or dimm driver down.... and if the high temp continues... off the driver...

saludos
Click to expand...
Honestly, I'm not sure how to do that. I have a multi meter but I'm not really sure how to use it. Can I test the driver without the cob? I've already thrown it away
 
salmonetin

salmonetin

Well-Known Member
tightpockt said:
Honestly, I'm not sure how to do that. I have a multi meter but I'm not really sure how to use it.
Click to expand...
...search tutorials about multimeter usage... but first you must know diferentiate input terminals from output terminals on a led driver... on input terminals you have 120 AC voltage (Beware) ...on outputs terminals we have DC voltages....

for measuring voltages we use multimeter on paralel conection ( + output led driver to + cob to + input dc multimeter... -output led driver to - cob to - input dc multimeter)
for measuring amperes we use multimeter on serial conection ( + output led driver to + input amp multimeter - input amp multimeter to + cob)...
...my english write its too bad ...maybe this can help you a bit...



http://www.ecolocityled.com/category/led_troubleshoot_multimeter

...on this vid they use multimeter for adjust a driver current... its not your case but maybe help you a bit too...


...or ask a friend or professional on your zone to teach you to use the multimeter that you use to measure voltages or ampers or miliampers on your led driver... a led driver a cob with heatsink and a multimeter can move easily...not?... ;)

tightpockt said:
Can I test the driver without the cob? I've already thrown it away
Click to expand...
...good question ...i dont know ... i think we need a cob for measurements... but its only my inexpert opinion too...

...

saludos
 
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