how to let the smoke out of LDD drivers?

_shorty_

New member
Okay.. This is my first bigger sized LED build, and I let the smoke out of an LDD driver, but I'm struggling to figure out why this happened. Are these drivers pretty sensitive? What are possible scenarios where you can ruin an LDD driver and eventually let out the smoke?

more info:
I have a 36V PS plugged into an O2 driver board. The other channels/colors work fine, but I'm having problems with my red string.

I am using radion pucks and added my own red to the center of each puck, which gives me 6 reds across two pucks that I'm trying to drive with LDD 500-H

PWM signals and ground come in via cat6 to the driver boards. PWM plugged in appropriately, ground from arduino joined with DC- from the PS. DC+ and DC- plugged in appropriately to inputs on the driver board. Output DC+ is going to input pin of puck 1, output of puck 1 attached to input of puck 2, output of puck 2 attached to DC- (output) from the driver board. Pretty straight forward... so you'd think... :headwally:

At first, the string wouldn't light up. I found a loose pin in one of the plugs. I corrected that, and it still wouldn't light up. So, after more troubleshooting, I found that one of my added LEDs was not working, so I disconnected that puck and replaced it with another puck in its place. After that, it still didn't work so I conducted some more troubleshooting that I'll try to explain: I know that all 6 LEDs in the string are functional. I have a 5V wall wart with 750mA output, and can put across any single LED to make it light up. I can also put it across any three LEDs in series on this string and succesfully light them up. I tested all links on the string with this method from the DC+ output of the driver board around to the DC- output of the board...

In addition, before the driver popped, if I adjust my voltage on the PS itself up or down, my DC output from the driver would always match exactly what the input voltage was. Because of that, I thought that maybe I had a short somewhere to the heatsink or something, but I can't find any continuity anywhere to the heatsink with my meter. I will need to order a couple more drivers now, but don't want to try another unless I think I have my problem fixed.

Oh - one additonal piece that is maybe normal, but I thought was questionalbe - if i put my 5V DC+ on the + of my LEDs on the puck without adding the DC-, they just barely light up. Is that normal?

I'm wondering if the drivers are a little sensitive, could the initial bad LED or unattached PIN cause the driver to fail, and it only blew up later? Or if I probably still have an issue somewhere?

Any ideas?
 

O2Surplus

New member
LDD's can be blown easily if you're not careful. I personally don't like the fact that MeanWell placed the PWM input pin right next to the VIn+ pin, as short circuits can happen very easily if the PcB gets contaminated with only a few small bits of copper wire. "Been there - done that". LOL- you get an even better "smoke show" if you inadvertently plug the LDD in up-side down. "Done that too".
I've got a few brand new LDD's if you need them. I won't be using them, since I can build my own A6211 based drivers for roughly the same cost as an LDD-H. Send me a PM if you're interested.
 

Redman88

New member
i have blown a couple of drivers (not LDD's) by plugging the 120 AC in into the dc voltage out. silly me didn't stop and think hard enough about the connections and what was writen there.
 

oreo57

Active member
if i put my 5V DC+ on the + of my LEDs on the puck without adding the DC-, they just barely light up. Is that normal?

I've seen that happen on some builds.. Only guess is some leakage current..

One thing I always test for is any "bridging" of an LED to the heatsink.

My way of testing this is to use my DMM to check from plus to heatsink and from minus to heat sink. Of course this is just w/ single 3v LED's..

My meter set to ohms has enough voltage to actually light (well barely light) an LED.. simple quick check..

Does this have ANYTHING to do w/ your above statement?.. I can't say..

I would like to find out why you can get "phantom" voltage and light an LED w/ just one lead..
 

_shorty_

New member
I've seen that happen on some builds.. Only guess is some leakage current..

One thing I always test for is any "bridging" of an LED to the heatsink.

My way of testing this is to use my DMM to check from plus to heatsink and from minus to heat sink. Of course this is just w/ single 3v LED's..

My meter set to ohms has enough voltage to actually light (well barely light) an LED.. simple quick check..

Does this have ANYTHING to do w/ your above statement?.. I can't say..

I would like to find out why you can get "phantom" voltage and light an LED w/ just one lead..

Thanks guys!
I've learned:
* 'don't plug AC into LDD input' - lol,
* And don't put the driver in backwards - he-he.
* And don't short PWM to DC in. I guess this is a possibility, but I don't see anything that would have done this, but I did route my wires under the boards, which if the shielding of those small wires tore, it could short the pins...

The 'bridge' to heatsink idea seems the most likely to cause those simptoms, especially since the DC output voltage from the driver voltage maxes out and matches the input DC voltage. It makes sense that the driver would pop, as current would just keep increasing to try and keep the constant current. Continuity testing did not successfully test this, so I will try the olm setting test next! Thanks guys!

Any other possibilities? Or good stories about blowing LDDs? I tell you what - my wife was MAD at me after i let the smoke out, cause she wasn't feeling well to begin with and the smell really ticked her off...
 

jedimasterben

LED world domination!
I'm a proud member of the 'placing one upside down on the board' club. Man, these things are like 0.5% metal, 0.5% plastic, and 99% smoke lol

IMAGE00005.jpg
 

_shorty_

New member
I think (hope) I figured out my issue. I think where I drilled through the heatsink, the edge was too sharp or something... I'm not completely sure where - but I'm pretty sure I was shorting red and green DC+ together (I think) - and I believe that's what popped my center red LEDs and the driver. Fortunately, no more damage was done. I don't think it was a constant connection/short - so it was difficult to troubleshoot.

I couldn't find any bridging between any LED and the heatsink..

I've done some wire cover patching with shrink wrap, replaced my center reds, and ordered more drivers. After I file my edges down I'll put her back together to test everything out again. Fingers crossed!
 
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