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Thread: Mighty Mini - HELP

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    Trying to behave here-NOT John's Avatar
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    Default Mighty Mini - HELP

    Finished the last 4 of my 8 MM boards today. Only had to solder in the Red LEDs.

    First two boards tested fine. The last two, well ............ have problems with the Reds.

    Visually inspected all the RED LEDs for proper polarity insertion. Using high power illuminated magnifier, inspected the solder joints, looked fine. Reflowed them anyway.

    The symptoms are as follows:

    BOARD A:

    Red 1 - 8 are out.

    Measured R1 at 103.6 ohms. No voltage drop across it.

    Red 9 -16 work fine. R5 measured 101.1 ohms with a voltage drop of 8.23 volts.


    BOARD B:

    Just the reverse. Red 9 -16 are out.

    R5 measured 95.6 ohms

    Red 1 - 8 work.

    R1 measured 100.2 ohms with a voltage drop across it of 7.15 volts..


    Any suggestions of what to check next?
    John (The Mascot)
    www.tennholidays.com

    480 LOR Channels + 2 CCR + 8 Mighty Minis + 10 Rainbow Floods+ 1 vdrive and vflood, Lynx Express and over 40,000 LEDs

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    This space for rent. Al in Raleigh's Avatar
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    Default Re: Mighty Mini - HELP

    Backward LEDs. Use the diode function on your meter or your 1.5 volt battery until you find it. Be careful though. The reverse bias voltage for those LEDs are very low and applying 24V power will eventually blow up the LED.

    What is the voltage drop on R5?

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    Registered User mschell's Avatar
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    Default Re: Mighty Mini - HELP

    For my simple testing, I took a 9V battery (the kind that goes into your smoke detector) and hooked some wire to the battery. I then take the neg and pos leads and put them across 3 or 4 of the LEDs. Battery can't deliver too much current, so it doesn't overdrive the LEDs. Note that 9V will only light up 3 or 4 of the LEDs in series, not the full 6 or 8, so you can't put it across the terminals.

    If you try the battery leads backwards (neg to anode, pos to cathode) you'll find out if your LEDs are backwards. I know that some of C-LEDs ones were reversed from what they were supposed to be.
    Mark

    New location - new display. Looking forward to 2015 season!

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    wrench twister TGabriel's Avatar
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    Default Re: Mighty Mini - HELP

    John did you find your problem with the MMF?

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    Trying to behave here-NOT John's Avatar
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    Default Re: Mighty Mini - HELP

    Sure did Thomas!

    On Board A: two of the red leds are dead! On board B: one of the leds died.

    Thank goodness Cece sent extra LEDs of every color, so I had 8 extra each of the red, green and blue plus 4 extra of the warm white and 4 extra of the cool white (plus extra resistors and terminal strips)

    Just haven't had time to unsolder and replace them yet. Will probably do it Sunday afternoon

    Need to get the MM project finished and out of the way, then be ready to start building a Lynx Express
    Last edited by John; 05-20-2010 at 09:41 PM.
    John (The Mascot)
    www.tennholidays.com

    480 LOR Channels + 2 CCR + 8 Mighty Minis + 10 Rainbow Floods+ 1 vdrive and vflood, Lynx Express and over 40,000 LEDs

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    This space for rent. Al in Raleigh's Avatar
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    Default Re: Mighty Mini - HELP

    John, did you test each LED before soldering? If not, CeCe knowingly sent extra LEDs due to a known failure rate. That ain't good. Mark bought LEDs for our group buy from Shop4Leds on Ebay and we had 0 failures.

    If the failures came from the supplier, I would recommend a stress test of the Mighty Minis in which you let the MM burn for several hours, then throw them into a freezer, take them out and burn for several hours, and repeat until you get sick of it. The extra stress from the heating and cooling will cause bad LEDs to die earlier and not when they are supposed to perform. I actually know quite a bit about this subject having worked directly in that field for years. We would call that style testing life cycle testing. You will likely reduce the life expectancy of the LEDs by 5-10% but will flush out early failures with the added stress. Poor solder joints will last no time with that style testing.
    Al

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    Default Re: Mighty Mini - HELP

    Quote Originally Posted by Al in Raleigh View Post
    John, did you test each LED before soldering? If not, CeCe knowingly sent extra LEDs due to a known failure rate. That ain't good. Mark bought LEDs for our group buy from Shop4Leds on Ebay and we had 0 failures.

    Al
    Yes Al, all LEDs were tested upon receipt initialy with the battery when I first got them.

    Before I started building the boards I had purchased the LED tester very similar to yours, and tested each LED before inserting the leads into the PCB. (just to reconfirm the polarity)

    ZERO failures !!

    For all I know, as rusty as my soldering skills might have become, I could have very easily fried them myself while soldering. Although the first six boards worked perfect and the blues, greens whites on these last two were great!

    I did have a lot of interruptions and distractions while doing the Reds on those last two boards, but was determined to "push on" and get them finished. I really should know better!

    I don't believe there is any problem with the LEDs from Cece, I really feel it was operator error on my part being "felt rushed to finish"

    I have heard from several sources that Cece usually includes "extras" with their orders, such as the extra resistors and terminal blocks that I also received, certainly parts that wouldn't have a "known failure rate", in my opinion just generous on their part.

    Kind of like the SPT plugs and sockets that I order from Novelty Lights, I almost always receive 130 or so with each order of 125 I make with them. So they always ship me more then I paid for, which is one reason I keep ordering from them.

    and I would have no hesitation about buying more LEDs from Cece in the future!
    John (The Mascot)
    www.tennholidays.com

    480 LOR Channels + 2 CCR + 8 Mighty Minis + 10 Rainbow Floods+ 1 vdrive and vflood, Lynx Express and over 40,000 LEDs

  8. #8
    This space for rent. Al in Raleigh's Avatar
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    Default Re: Mighty Mini - HELP

    Ah Ha. We know the problem now. John can't solder. John can't solder. John can't solder. John can't solder. John can't solder. John can't solder.

    Nanny nanny poo poo. John can't solder. John can't solder. John can't solder.

    I'm feeling a country and western song coming on. Something along the lines of

    "Mama don't let you babies grow up to be no soldering insurance men".

    Get your best party dress ironed John, the convention is only 3 months away. I didn't get to say 2 sentences to you last year thanks to AL parking her butt in TX and forcing us to put on the Red Cup Social. AL had best not weasel out this year.

    Al

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    Default Re: Mighty Mini - HELP

    Hey, its been 40 years since I was paid to solder. And that was on vacumn tube stuff using a 150 watt iron!

    Annalisa will be there this year and between the 3 of us hosting, it will be a party to remember! Think maybe I should pack my tux?
    John (The Mascot)
    www.tennholidays.com

    480 LOR Channels + 2 CCR + 8 Mighty Minis + 10 Rainbow Floods+ 1 vdrive and vflood, Lynx Express and over 40,000 LEDs

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    wrench twister TGabriel's Avatar
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    Default Re: Mighty Mini - HELP

    Think maybe I should pack my tux?

    So you are going out with the Red Hats

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    This space for rent. Al in Raleigh's Avatar
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    Default Re: Mighty Mini - HELP

    Quote Originally Posted by John View Post
    ... Think maybe I should pack my tux?
    I'm not. I might wear my best t-shirt.

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    xLights or BUST in 2018 kidcole's Avatar
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    Default Re: Mighty Mini - HELP

    Darn, I was hoping to wear my Tux too !
    Attached Thumbnails Attached Thumbnails -denny-cole-dj-karaoke.jpg  
    Last edited by kidcole; 05-22-2010 at 01:59 PM.
    Thanks,

    Denny Cole
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    Trying to behave here-NOT John's Avatar
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    Default Re: Mighty Mini - HELP

    Quote Originally Posted by Al in Raleigh View Post
    I'm not. I might wear my best t-shirt.
    The PINK one, that matches Walter's shorts ?

    Bring it on Denny ! At least we will look like gentlemen !
    Attached Thumbnails Attached Thumbnails -johntuxnohat.jpg  
    John (The Mascot)
    www.tennholidays.com

    480 LOR Channels + 2 CCR + 8 Mighty Minis + 10 Rainbow Floods+ 1 vdrive and vflood, Lynx Express and over 40,000 LEDs

  14. #14
    This space for rent. Al in Raleigh's Avatar
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    Default Re: Mighty Mini - HELP

    Quote Originally Posted by John View Post
    At least we will look like gentlemen !
    Maybe, but the rest of us will know who are the butlers.

    I only wear monkey suits on cruises and no John it ain't pink. I know for a fact that the Red Cup Socials don't have a Captain Stubing. Could one of you two get me a drink please? Chop. Chop.
    Last edited by Al in Raleigh; 05-22-2010 at 05:31 PM.

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