My first holy smoke moment

Discussion in 'Power Supplies' started by GCAllan, Sep 27, 2015.

  1. GCAllan

    GCAllan New Elf

    Joined:
    Jan 12, 2015
    Messages:
    26
    Likes Received:
    7
    Location:
    Burleigh Waters
    Hi all


    Was playing around last night trying to get a little 6 channel controller working off a 30 channel controller when things went bang crackle and pop followed by smoke.


    I am at a loss at what I did wrong and have attached a little diagram of how I hooked it up. I did notice that the power/dmx light on the 6ch came on before I connected the 24v power supply. The smoke happened once I connected the power supply. Can you not join 12 and 24 together via dmx?


    Tested the 30 channel this morning to ensure it was ok and it seems to be working ok, the 6ch however seems to be dead as a door nail.


    Any pointers of what could have gone wrong would be appreciated.


    Thanks


    Al
     

    Attached Files:

  2. scamper

    scamper Senior Elf

    Joined:
    Jan 5, 2014
    Messages:
    736
    Likes Received:
    37
    Location:
    collie
    Find Me On:
    Not sure why you connected the 24v at all.
    If you have big w strings etc that require 24v to run, then the power should be applied to the strings only and not to the board.
    In saying that, I am not sure / familiar with the boards you are using
     
  3. AAH

    AAH I love blinky lights :) Community Project Designer

    Joined:
    Dec 27, 2010
    Messages:
    2,507
    Likes Received:
    1
    Location:
    Eaglehawk
    Find Me On:
    Most of the better dmx board designs have electrically isolated dmx inputs. As the 6 channel board was lighting up from the dmx line it pretty much rules out that it is isolated. Your drawing looks fine to me so my 1st thought would be that maybe your power for the 6 ch board was reversed. You can join pretty much any voltage together via dmx when the dmx lines are electrically isolated 5V, 12V, 24V and 240V are all commonly done.
    Can you post a pic of where the smoke emitted from if you happened to have seen the spot.
     
  4. OP
    OP
    GCAllan

    GCAllan New Elf

    Joined:
    Jan 12, 2015
    Messages:
    26
    Likes Received:
    7
    Location:
    Burleigh Waters
    Hi fellas
    Thanks for the response, I was trying to use the 6ch to power a bigw string exactly at 24v so I was powering the board at 24v. My poor Brian couldn't workout how to power the string directly at 24v and then send 12v from board to power the string. Is it even possible?



    I attached a photo with a red circle of where I believe the smoke came from. If it wasn't that blurty then it was something next to it. Vague I know. :-[


    Double checked power with multimeter, definitely right way around.


    Thanks


    Al
     

    Attached Files:

  5. scamper

    scamper Senior Elf

    Joined:
    Jan 5, 2014
    Messages:
    736
    Likes Received:
    37
    Location:
    collie
    Find Me On:
    Well that is a 5v regulator and should be able to regulate up to 40v (theoretically)
    So it really shouldn't be the 24v that caused it.
    I can then only assume there is a problem with the current you were drawing.
    ie you have a short on the strings, they are wired up incorrectly or there are too many therefore drawing to much current.
    In saying that, as big w strings are designed for closer to 28v it may be they were drawing a lot more current than they should have as the voltage was lower.
    If you have a soldering iron and are lucky, you may be able to just get a new regulator and replace it to get it all working again.
    To hook up string to run on a different voltage than the controller all you need to do is run the controller on the voltage required. Then hook all the -v lines to the outputs (for R G B ) then instead of hooking the +V to the controller, you power it from the supply you want and just connect the -V from the 2 power supplies together.
    ***This will work for most power supplies, I have never had a problem, but there are rare cases that 2 power supplies may not like this.
     
  6. David_AVD

    David_AVD Good news, everyone!

    Joined:
    Jun 12, 2010
    Messages:
    3,345
    Likes Received:
    22
    Location:
    Victoria Point (Brisbane)
    I did a wiki article ages ago that may help show how to use different voltages on one controller.
     
  7. i13

    i13 Senior Elf

    Joined:
    Jul 5, 2013
    Messages:
    775
    Likes Received:
    6
    The Big W strings should have more than 24V DC. This won't have caused the damage but it is an issue in your setup.

    Increasing the voltage increases the current and it is current that lights up the LEDs. If your voltage is too low then the current will be too low as well. This'll stop them lighting up (or they'll be dim) but it won't increase the chance of damaging anything.

    Another small problem that again shouldn't damage anything is that you don't seem to have a terminating resistor. You need to connect a 120 ohm resistor between the unused DMX+ and DMX- outputs on the last DMX controller. This resistor needs to be able to handle at least 0.25 watts.

    I think it was fine to power the board the way that you did. The only time you shouldn't connect the +24V to the board is when you're using multiple voltages on a board that only has one power input (see example 2 in David_AVD's wiki article).

    Have you rechecked that the three DMX input wires were connected the right way around on both controllers?
     
  8. OP
    OP
    GCAllan

    GCAllan New Elf

    Joined:
    Jan 12, 2015
    Messages:
    26
    Likes Received:
    7
    Location:
    Burleigh Waters
    Hi all


    As my father said to me yesterday, it's only when you let the smoke out things don't work, the secret is to keep the smoke in. ;)



    Firstly thanks for the advice from everyone especially David. I used spare outputs on my 30ch controller with separate power supply to the +Ve on the lights according to your wiki and now am the proud owner of some Blinky flashy bigw strings and icicles. Was running around like a kid in a lolly shop last night.


    As for the 6ch controller I'm putting it down to what Alan said, not electrically isolated or maybe I just got a dud one, oh well there goes 17 bucks.


    Onto my next element, it seems I'm running out of time, still lots to build.


    Thanks


    Al
     

Share This Page