Fried Egg

tightpockt

tightpockt

Well-Known Member
salmonetin said:
...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... maybe help 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?... ;)



...good question ...i dont know ... i think we need a cob for measurements... but its only my inexpert opinion too...

...

saludos
Click to expand...
Thanks, so the driver has to be hooked up to the cob to get a reading? I'm not sure how to do that without blinding myself
 
salmonetin

salmonetin

Well-Known Member
tightpockt said:
Thanks, so the driver has to be hooked up to the cob to get a reading?
Click to expand...
...from my inexpert pov... yes... with wires because you must use cob with heatsink ... but its only my opinion

tightpockt said:
I'm not sure how to do that without blinding myself
Click to expand...
...i saw on youtube vids people using cardboards or similars...

....but you can use a tipycal reflector from a desk lamp to cover the cob with the reflector (not totally) and you can evitate the direct light (dangerous) to yours eyes... and with the indirect light you can check if your cob are ON or OFF...



pd...Wilson... time to infusion back to the cavern...

pd1... i told you Wilson...well at least i try... time to read other answers...

...good luck TP... have a nice day...

saludos
 
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SupraSPL

SupraSPL

Well-Known Member
stardustsailor said:
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 ...
Click to expand...
If I recall, the CXA that burned on you was due to a large air bubble in the middle of thermal paste, and it was running at 2.15A? I agree the Vero29 suffers slightly less temp droop than CX 3070 series, but really it is the CXB3590 that is fair game to compare against. There are many hundreds/thousands of CXA/B3070s in operation as grow lamps and this is the first failure I have seen that quite honestly has me baffled, unless it somehow came off the heatsink, that would explain it.
 
stardustsailor

stardustsailor

Well-Known Member
SupraSPL said:
If I recall, the CXA that burned on you was due to a large air bubble in the middle of thermal paste, and it was running at 2.15A? I agree the Vero29 suffers slightly less temp droop than CX 3070 series, but really it is the CXB3590 that is fair game to compare against. There are many hundreds/thousands of CXA/B3070s in operation as grow lamps and this is the first failure I have seen that quite honestly has me baffled, unless it somehow came off the heatsink, that would explain it.
Click to expand...
Yes,exactly .
One of the CXAs that I've shown here ,had a destroyed LES(although the COB itself was still fully operational ,as it had no fried dies under its LES ) .And the main reason behind was an overtighten Ideal holder,putting uneven pressure .
In my books ,that is part a design flaw of the holder and part a mishandling of the holder.
In this case here ,the most probable reason behind the failure ,is the ceramic substrate of the COB.
Quite of a few two -part thermal epoxy compounds ,have really hard time to adhere to that ceramic surface.
Add the fact of three different thermal expansion coefficients (substrate -TIM -heatsink = ceramic -polyepoxides-aluminium ) ,and here's the recipe of well-done fried eggs ..
Things could have been different if thermal silicone adhensive was used ,as it withstands more mechanical abuse ,
from thermal expansion.Still ,that is just an assumption .(Not tested ,at least not by me ..Yet ...)

Time will show ,about the rest COBs ,already in use or ...in abuse ..

Cheers.
:peace:
 
Greengenes707

Greengenes707

Well-Known Member
If you want to have the best, you have to harness the best from the best. From chips to drivers to TIM to heatsink to reflectors/lenses and every other component. If anything is missing... you suddenly don't have the best anymore. And possibly even a problem depending on where you skimped or made a mistake. You could use a top bin and shitty drivers or a mid bin and a top tier drivers and have the same light in the end.
If everything is the same down the the scews but one can maintain 32c and the other 50c...someone has a better cooling/mounting process and is making a better light from the same tools. Some would call that craftsmanship for small scale...precision tolerance for production.
Regardless...the best is required at every level to in the end have "the best".

We have known how important cooling is since the beginning. And also how a high wattage point source is a bigger task than other platforms of LED light.

As for this particular situation. To me that TIM is poor plus applied poorly(no offense). Too much extra ooz and the corners aren't covered. So just speculating, but doesn't look like even pressure and coverage.

My 2¢ are deposited
 
tightpockt

tightpockt

Well-Known Member
Greengenes707 said:
As for this particular situation. To me that TIM is poor plus applied poorly(no offense). Too much extra ooz and the corners aren't covered. So just speculating, but doesn't look like even pressure and coverage.

My 2¢ are deposited
Click to expand...
You're probably right, those first couple of cobs I was putting a pea sized amount in the center and then pushing down, right next to the les on the raised circle portion with pencils (eraser side down)
I've since switched to spreading a thin layer on both the heat sink and cob and applying pressure using the same method.
What's troubling though is that I used the Arctic epoxy to avoid drilling and tapping and when I barely touched the cob the whole thing flaked right off..leaving that burnt looking heat sink.
 
salmonetin

salmonetin

Well-Known Member
...TP`please....only for my curiosity what led drive it is? brand... model .... one driver for cob?... ... various cobs for one drive?... cobs conected on serie or paralell conection... ????

saludos
 
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dionysus4

dionysus4

Well-Known Member
i cooked 2 cxa 2540s recently- havnt checked the back yet but the front is exactly the same- half the diodes( 2 centre rows) failed and now the light comes on only for a few seconds- it blinks so to say

i used a thermal pad as a TIM( i know i know ) but actually my heatsink was getting up to 67c after 10 hours on driving at 1.3A

so i assume my sink could not dissipate the heat fast enough

what type of sink is that?
 
tightpockt

tightpockt

Well-Known Member
I need to buy a replacement and I could just get the cxb3070 AB from digikey, it's in my cart right now but before i pull the trigger does anyone know offhand what the part number for the highest bin cxb3070 and could tell me so I dont have to go scouring through 1000's of pages, i know, i know, i'm being a lazy asshole
@SupraSPL @stardustsailor @Greengenes707
ALso, I have some holder and ledil adapters on the way. I know a few months ago when I was searching hard I was having trouble finding the ledil reflectors. Has that changed or does someone carry them now?
 
mc130p

mc130p

Well-Known Member
tightpockt said:
I need to buy a replacement and I could just get the cxb3070 AB from digikey, it's in my cart right now but before i pull the trigger does anyone know offhand what the part number for the highest bin cxb3070 and could tell me so I dont have to go scouring through 1000's of pages, i know, i know, i'm being a lazy asshole
@SupraSPL @stardustsailor @Greengenes707
ALso, I have some holder and ledil adapters on the way. I know a few months ago when I was searching hard I was having trouble finding the ledil reflectors. Has that changed or does someone carry them now?
Click to expand...
digikey shows lots of specs on their page without even having to open the datasheet...so to easily get the highest bin of a certain color temp, choose the one with the highest lumen output
 
alesh

alesh

Well-Known Member
tightpockt said:
I need to buy a replacement and I could just get the cxb3070 AB from digikey, it's in my cart right now but before i pull the trigger does anyone know offhand what the part number for the highest bin cxb3070 and could tell me so I dont have to go scouring through 1000's of pages, i know, i know, i'm being a lazy asshole
@SupraSPL @stardustsailor @Greengenes707
ALso, I have some holder and ledil adapters on the way. I know a few months ago when I was searching hard I was having trouble finding the ledil reflectors. Has that changed or does someone carry them now?
Click to expand...
Gosh, typing this question probably took more than checking it against the data sheet :finger:
CXB3070-0000- 000N0HAD30G
 
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