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Bypass MFC BigW & Kmart type LED Lights

Discussion in 'Power Supplies' started by madmaxisback, Nov 6, 2015.

  1. madmaxisback

    madmaxisback New Elf

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    Ok, this is my first post. I did a few searches first but didnt find info I need.

    I have 3x CTB16 LOR AC units and I want to run several existing BigW and Kmart LED lights I have from various years on this controller.

    As they are all 31v Changzhou Jutai MFC they need to be modified to run on the LOR.

    I have opened up one of the MFC and they don't look like any of the boards on the wiki. :-\

    Any suggestions on which wires I need to bridge to make them stay on constantly would be very helpful.

    [​IMG]




    Thanks in advance
     

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  2. i13

    i13 Senior Elf

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    Unfortunately those are the lightweight plugpacks which break sooner or later when you try to use them with a 240V controller. You can only turn them ON or OFF; no dimming or fast flashing. They also usually have a delay between when you turn the power on to them and when the power outputs to the lights. The AC controllers are really for strings of lights that have 240V running their entire length.

    Fortunately those lights are old so they're likely to have three wires between the controller and lights. This means you can use them with DC control but it would be difficult to set up in time for this year. DC control replaces the 8-function controller.
     
  3. OP
    OP
    madmaxisback

    madmaxisback New Elf

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    Ok Cheers for the great info! :)

    I have 2x LOR CMB16D DC controllers and a pair of Meanwell S - 350 - 27's I was going to use for my faces and other elements of the show.

    Would you be able to point me in the right direction to use these for the BigW strings?

    Thanks
     
  4. dale82

    dale82 Senior Elf

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    I would do some more research before you purchase anything else mate. Pixel are a great option instead of 240v LOR gear. Especially from a safety aspect.
     
  5. OP
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    madmaxisback

    madmaxisback New Elf

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    Thanks Dale

    I personally don't like the Pixels as much as the "warmer" LED lights for a Christmas show. Personal preference I suppose. Just think the Pixels are a little clinical.

    As I have over 500m of these BigW type lights I would like to have a go at getting the MFC bypassed if anyone can advise on which wires should be soldered

    This one looks similar to mine (closer than ones on wiki)
    http://auschristmaslighting.com/forums/index.php/topic,6439.msg57303.html#msg57303
     

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  6. i13

    i13 Senior Elf

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    It's not a quick process to get those lights working with DC control for the first time and I'm yet to find a very good resource on how to do it. This is me briefly explaining what to do but I'm assuming there are 3 wires between the controller and lights and that the light sets have resistors within them (KMart sold some that don't). There should be two negatives and one positive. It's not hard to modify this method for light sets without an 8-function controller but it won't work at all if there is an 8-function controller AND only 2 wires going to the lights.

    You need to calculate the correct current draw by counting the number of sections between where there are only 3 wires and multiply this by 10mA. The end section often only has three wires so count this too. I don't recommend doing this with the Mean Well supplies because their input is too close to their output (dangerous). Turn your power supply down as low as possible, measuring the current for one channel within the light set with just the lights connected and no plugpack. Increase the voltage until you reach the current you calculated. You'll find this occurs at different voltages for different light sets so you'll need to add diodes to each of the negatives of some light sets to drop about 0.5V each. Retest with the diodes connected until you have everything running at the same voltage. You might need to remove LEDs to lower the voltage your light sets run at. Remove two LEDs between each section of 3 wires and leave an even number (or none) LEDs between the ones you remove. It's never a bad idea to start testing with diodes already connected too because this effectively lowers the minimum voltage for your power supply and reduces the chance of exposing the lights to a voltage that's too high.

    You'll need to do this for all light sets unless they're bought from the same place, same year and same colour. Multicolour light sets need each channel tested separately.
     
  7. AAH

    AAH I love blinky lights :) Community Project Designer

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    The 1 that you linked to appears to be a 2 channel controller. The 1 that you have appears to be a 4 channel 1 judging by the fact that there is Q1 through to Q4. I can't make out how many wires are coming out. I can see at least 3 and the copper side of the pcb isn't a good enough photo to tell how many of the pads have wire attached. If you can post some better pictures which actually show the tracks around the output wires clearly then we may be able to advise better. Looking at the design of that board it looks like it actually uses switched DC to control the lights and as such you should be able to hook them up to a DC dimmer. The value of the large green capacitor may give some indication of the voltage that the lights run on. All that is visible is a 3 which could mean it's something like 330uF /50V or it could be something like 220uF 35V.
     
  8. OP
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    madmaxisback

    madmaxisback New Elf

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    Thanks guys.

    I like the idea of using bypassed MFC this year and going to DC next year. If I hook them up to LOR AC unit they work fine, but not steady on. My show isnt going to be crazy intense this year anyways. Just on or off... now twinkles for special smoke effect!

    Alan, here is a better image
     

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  9. AAH

    AAH I love blinky lights :) Community Project Designer

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    Okay that picture is much better but it's the other side that's really important. The large green capacitor has 2 thick pcb tracks coming from it. 1 goes directly out to the common black wire. The other thick pcb trace is the 1 that needs to be joined across the 2 transistors Q1 and Q3 (I think). The picture isn't good enough or I'd scribble up a bit of a connection thingy with paint to show you where to bridge.
     
  10. OP
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    madmaxisback

    madmaxisback New Elf

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    Another 2

    Green cap is 100uF
     

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  11. AAH

    AAH I love blinky lights :) Community Project Designer

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    This should do the trick for you.
    If you can still get these exact lights then that is a win as Big W, KMart and just about everyone else has changed over to a more complex control circuit which allows them to make the actual strings a lot cheaper.
     

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  12. OP
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    madmaxisback

    madmaxisback New Elf

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    Soldiering iron is on! Thanks mate - Legend! :)

    I have 30 plus sets so I think I should be busy for a while... I have joined a few of the shorter ones together so they were in sync last year so I will test these also.


    UPDATE! Success! It worked perfectly

    Thanks once again for your expert assistance Alan!
     
  13. OP
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    madmaxisback

    madmaxisback New Elf

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    Ok, so I did 5 of my MFC, then I found another one which is different again to all the others. 36v version
    (PCB - 158 - 2012 -01-06)

    Better images this time. If I could please ask for your help again Alan I would be very grateful?

    Thanks
     

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  14. dfarcher

    dfarcher New Elf

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    Pretty much the same as the others.
     

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  15. AAH

    AAH I love blinky lights :) Community Project Designer

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    Yep. Looked like Darrin got it in 1.
    Are these lights available still/easily as I will add these details to the wiki if there's any likelihood that others will have these lights.
     

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