Lighting How to diagnose electrical issue? Solved with some Info on heat transfer for Max efficiency.

[grow-pro]

So i just built a 250 watt system with a HLG-240H-C1400B and 5 citi 1212 3500K 90 CRI. I plug it in the first time and it is unbelievably bright. I unplug it after about 10 seconds install the reflectors and it wont turn on again. I check and replaced every single connection so it looks like a component failed. My system is in series. I'm off to the store to buy a multi meter as I don't have one at my apartment. Any pointers for checking for voltage or continuity on each component to make sure everything is working?

 

[dragondust]

Get a meter. First check the driver with no load. The spec for that driver is 180v.

Looking at the spec you might be pulling to many volts for this driver. 36x5 is 180v which is max for this driver. If you have a dimmer hooked up. You can try dimming them at 50% first and then try turning them on. The lower the current the lower the volts the cob requires.

The other option is to remove 1 cob from the series.

 

[dragondust]

Going by the citi led calculator for the gen 5 the 1212 at 1400ma is 36.7v which will give you 183v. That your issue. You need a bigger driver or drive the cob at lower current at 1050ma you need only 35.7v

 

[dragondust]

Also what cob holders are you using? Bjb or ideal?

 

[grow-pro]

Got another multimeter opened it then remember I noticed that last night there was a mixed batch m3 screw heads that came with my leds and holders. Some were philips with the built in washer while others were philips without the washer. I was paranoid that different screws might press down differently and not evenly spread the thermal paste so i swapped them out. Looks like when i did one of the cobs fell off the contact with the holder. Problem solved wasted money on an extra multimeter. I guess now I can keep one on the boat and one in the apartment.
Ideal holders are definitely the way to go. Metal elasticity will provide the best pressure and wont creep over time like plastic. More pressure will slightly deform asperities leading to the greatest contact between metals and the thinnest thermal paste interface for the best heat transfer. I also recommend use 4 screws even if you don't have reflectors to push down equally from 4 points in stead of 2.

Also mine are gen 6 I'm all about the greatest heat transfer for best efficiency.

Another note about heat transfer I was thinking about removing the black anodize(a thicker layer of electrolitcally deposited aluminum oxide) under the cob because aluminum oxide has a thermal conductivity of 30 W/mK which is far worse than the thermal conductivity of the aluminum of the cob and the heat sink (~237 depending on the alloy). I then remembered however that the thermal conductivity of the paste is only 8.5 W/mK. The anodize is so thin and very insignificant but if I some how I made the surfaces rougher I might increased the thermal paste layer and have even worse heat transfer. So just in case anyone else was thinking about sanding off the anodize I decided that it wasn't worth it and might even make it worse. Also black anodize is def a plus on all of the other surfaces as it increases radiation heat transfer to surroundings.

 

[dragondust]

I glad it was only a lose connection. The gen 6 run a low voltage. Can you give me a total voltage of the dc side under full load.

 

[grow-pro]

I put the leads of the multimeter to connect the final circuit and the cobs light up going through the multimeter but the numbers don't make sense. It reads differently ranging from 1.7 to .5 V and it doesn't go to zero when i break it away from the circuit. I tried measuring some dc adaptors lying around and it still doesn't make any sense. I used all the DC voltage settings from 200mv to 600v and nothing seems to work. I guess that gives me grounds to return it.