OOPS.... Burnt Cob of Corn (Minus the Corn)

So there's that.....I turned them off and poked my head under for some maintain and noticed I burnt some of the cobs! They still work, but I imagine they're way less efficient now... Only 2/12 Cobs were affected.
So two questions...

1) Could I still run them or are they fire hazard?

I have a Clip-fan blowing across the top, as I found the heatsinks to be warm to the touch. Where the fan was blowing strong they were cool. Some corner ones stayed warm to the touch because they didn't get hit by the fan as well.

I purchased them as a "package", so I thought those heatsinks were enough for the cobs (Or the seller would not have sold them as a package together?... or so I thought?). I never ran the cobs more than 70% full strength, because I found the heatsinks slightly warm.

2) If I add another clip fan to the top would that do? Or is there a better alternative that won't break the bank to improve the setup so I can run them at 100% without worrying about burning any more Vero's!


Driver: Mean Well HLG-480H-C1750B
Heatsink: 144mm Pin Heatsink (1 per cob)
Vero 29 Se Cobs (6 per Driver)

I need to invest in a Temperature Device, so I could not tell you the temperature of the heatsinks right now. Just that the ones not getting clip-on-fan-air were warm to the touch, like the heater vent on your car after you use it.

That's crazy!!! But if you can blow air evenly over all the sinks, I think it'd make a huge difference.

That's uhhh., that's not good there.....
There has to be a problem under that COB, poor thermal transfer to the sink, there's now way those passive sinks should be allowing that level of heat to concentrate in that location.....

That's what I'm thinking. I run essentially the same cob and sink @ the same power levels with zero issues. I'd say that your thermal interface(TIM, paste, whatever) isn't thermally conductive enough and you're getting localized hotspots-I'd plan on replacing those chips.

I think you guys are right. Maybe I should have tightened them more, I just didn't want to over tighten them. I used those sticky thermal "pads". Do you think thermal paste would be better?

@GBAUTO at 100% are your sinks hot to the touch?

Sticky pad? Do you mean Gap Pad?

That is the downside to those connectors.. \
We had the solder on ones... When our 12V power system for the fans went down, the COBs desoldered the wires themselves...

We just had to resolder everything and had to replace only 2 of the 15 that went out.

Thermal paste > pads, but should be applied as thin as possible, it is only there to fill microscopic voids.

Them heatsinks cant handle that many heat watts.you want 150mm or 125mm splayed. Also 6cobs in series is a deadly.. Who sold you that?

Jerry and other likes to add the thick 1mm blueish M3 thermal pads. These are not enough and overheating COB's are a common problem unless you run them at only 20-30w. Get a good thermal grease like Arctic Silver or so and apply only a thin layer with the help of an old credit card or so. Press it well and turn it back and forth to get rid of any air pockets then screw it tight. But not more than 2-3N.m torque you do not want to break the plastic.

Ah I see. Another kingbright kit gone wrong. I've had many unhappy customers from them, dunno why they get a good rep.

Graphite pads are legit.

Airwalker16 said:

Graphite pads are legit.

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Yup, they way better as the cheap blueish ones and even better as some cheap thermal greases.
But they are considerably more expensive than 10g of good thermal grease. At least when I last searched for them 2 years ago..

I honestly really like the bluer gap pad. Never had any issues with it .

Airwalker16 said:

I honestly really like the bluer gap pad. Never had any issues with it .

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Lucky guy! I lost 2 CXB's because of these pads maybe two years ago and a few friends had the same problems with Jerry's M3 pads. Because of it's 1mm thickness even the Ideal holders were slightly bent. The CXB's only ran at 1050mA (37w) and the heatsink temperatures were consistently below 40°C with activ cooling. They feel like kneading kit somehow .. maybe if they were thinner they would work better ..? I did not measure mine but they certainly had 1mm or more.
Similarly thick adhesive pads were formerly in the Arctic Cooling custom coolers for my graphics cards but only to stick small heatsink on the memory modules. For the GPU there was some Arctic 4 thermal grease in a small 1g sachet and they explicit recommended to not use the pads for the GPU.

That was the fixture I had back then ...

0.5mm Arctic thermal pads tested best. Went through hundreds of them no problems.

Nice light @Randomblame I used to use amplifier cases to make LFSW cmh ballasts.

Randomblame said:

That was the fixture I had back then ...
View attachment 4173916 View attachment 4173917

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Reminds me of an eighties HiFi...

Lol

That's exactally what it is @Moflow well a higher end one I believe. Quite useful for bulding things.

Who the fuck say it makes no music, lol!
Fully ramped up the gals started praying all the time and sing Halleluja..

I had trouble properly seating my cobs once. I had to get shorter screws as some bottomed out on pins, so be careful when trying to seat them as the screws are easy to strip or snap off if they are even a little too long.
I also recommend thermal paste instead of the pads. I use arctic silver on my computer parts, but a cheap tube of halzynite paste of amazon for lighting.