Circuit won't turn off

Discussion in 'General Electronics Chat' started by TexasBluesGuitar, Feb 27, 2015.

  1. TexasBluesGuitar

    Thread Starter New Member

    Feb 27, 2015
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    Hello all, I am a newbie to electronics and circuits, but am a professional programmer. I have dove into the IoT and am now learning all about circuits. So here is a question related to a real life situation. I tried to change the light bulb in my bathroom. The light bulb is in the middle of an 8 bulb above mirror fixture. I left the power on while I was changing the bulb. During the change as I was screwing it in a massive spark happened and the bulb failed to turn on. Now the dimmer switch cannot turn off. It does not work and the lights have been on all night. This time I am going to shut the power off to the house and change the bulb, but I think the switch is broken. What do you all think?

    Texas Blues Guitar
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    How many professional programmers does it take to change a light bulb?

    Nul.

    It is a hardware problem.
     
  3. MrChips

    Moderator

    Oct 2, 2009
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    When you unscrewed the light bulb with the power on, it caused a short circuit across the contacts. All eight bulbs are wired in parallel powered by the light dimmer. The thyristor in the dimmer is blown, failed short.

    You can replace the thyristor with Q4006.
     
    planeguy67 likes this.
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I can see the Triac being shorted, but these types usually have the on/off sw also?
    Max.
     
  5. TexasBluesGuitar

    Thread Starter New Member

    Feb 27, 2015
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    Awesome Mr. Chips. Now I just need to figure out what a thyristor is and how to replace it :)
    thanks,
    TBG
     
  6. TexasBluesGuitar

    Thread Starter New Member

    Feb 27, 2015
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    It is a leviton HCM06 x10 dimmer. I have to press the dimmer in to turn it off and on.

    TBG
     
  7. wayneh

    Expert

    Sep 9, 2010
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    I think you should turn off the appropriate circuit breaker, not all of them, and have an electrician come take a look.

    I speculate that a poorly installed fixture - perhaps installed by the previous owner? - may have caused an intermittent short when you wiggled it and that short damaged your dimmer. It likely needs to be replaced. Just speculation.

    You can do this work yourself as long as you keep safety in mind at all times. Get a circuit tester or multimeter so you can detect whether a circuit is live or not, and use it before you touch any conductors.
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I am guessing when the lamp was screwed in the lamp holder turned and shorted the L&N together, it should also be checked by dropping the fitting of the wall and check the wiring otherwise the same thing may happen the next time you change the lamp.
    Max.
     
  9. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    745
    Try a BTA08-600 Triac, or have a look inside the dimmer,post pictures
     
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Whatever you do, first ensure the circuit-breaker for the light circuit is OFF before dismantling the light fitting.
     
  11. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Don't buy anything, don't take anything apart.

    Make the call and hire a licensed electrician to replace the failed dimmer.
     
  12. darrough

    Member

    Jan 18, 2015
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    You should be aware that if work is not done by a licensed electrician, and anything subsequently happens that might even been possibly caused by said work, your homeowners insurance will not cover any of it.
     
  13. MrChips

    Moderator

    Oct 2, 2009
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    Assuming the dimmer switch looks like this:

    [​IMG]

    Step 1. Turn on the bathroom lights.
    Step 2. Go to the service panel and turn off the breaker feeding the lights. Confirm that the lights go off.
    Step 3. Remove the control knob by giving it a firm pull.
    Step 4. Unscrew two screws holding the dimmer switch cover plate.
    Step 5. Unscrew two screws securing the dimmer switch.
    Step 6. Disconnect the three wires connecting the dimmer switch while making notes on which wire goes where.
    Step 7. Replace the dimmer switch with a new one from your local hardware store.
    Step 8. Reassemble switch and cover plate (follow steps in reverse order).


    Maybe your switch looks like this:

    [​IMG]

    If so, here is the manual:

    http://www.smarthome-products.com/productspecs/2209wi Manual.pdf
     
    Last edited: Feb 27, 2015
  14. TexasBluesGuitar

    Thread Starter New Member

    Feb 27, 2015
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    Thanks all. Yes it looks like the second switch. I am now thinking about replacing the whole fixture with a string of 12V LED lights. I dont think i need house ac current for that. Maybe a 12V adapter attached to a potentiometer in some kind of circuit. This is where my noobiness shows. Or should I replace the dimmer and build a 12V adapter for inside the switchbox with the dimmer style like the first picture? Then I could us the original wire used to connect the old fixture,


    TBG
     
  15. wayneh

    Expert

    Sep 9, 2010
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    I agree with MrChips' prescription. It's exactly what I would do. No way would I try to repair a damaged dimmer.

    I would add a step or two to look at the fixture while its power is off. I'd take it off and look for wires that are kinked or have frayed or scarred insulation, look burnt or anything else that looks amiss. Maybe a socket that has broken loose so that it rotates when you turn the bulb.

    If you want LED bulbs, replace the existing bulbs with those. Be sure to get dimmable ones.
     
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