Dimmer switch keeps light on

Discussion in 'The Projects Forum' started by falco84, Mar 11, 2015.

  1. falco84

    Thread Starter New Member

    Mar 11, 2015
    4
    1
    Hi. I'm hoping I might be able to get some help with a little home project. Recently my floor lamp blew a fuse. I took apart the light control panel to get to the curcuit board, replaced the 5 amp fuse and put everything back together. The problem is one of the dimmer switches (the top one in the picture, there are 2 of them) stopped working - one of the 2 lights doesn't turn off and can't be dimmed. The only way to turn it off is to unplug the lamp. The second switch and light work fine. How do I troubleshoot this? Is it possible that the switch was affected when the fuse blew?
     
  2. #12

    Expert

    Nov 30, 2010
    16,306
    6,816
    The triac is shorted. Replace it.
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
    745
    Triac blown, can you take pictures of the black vertical 3 legged components with the metal tabs on them ...
     
  4. falco84

    Thread Starter New Member

    Mar 11, 2015
    4
    1
    Here are the photos of the triacs and the back of the circuit board. Is there any way to test them to know which one is shorted?
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,553
    2,375
    Resistance meter, preferably out of circuit, it will be the one nearest the pot that controls it.
    Max.
     
  6. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    745
  7. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
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    if its fairly new, email the mfgr, they have replaced bad boards for me before. you will just have to disconnect the old one and put in a new one. I have had dinmers and ballasts go out on lamps before on lamps that were over a year old and they sent me the parts free.
     
  8. falco84

    Thread Starter New Member

    Mar 11, 2015
    4
    1
    Thanks for all the advice guys. I'll try to replace the faulty triac and will post an update when all is done. I am a complete newbie when it comes to circuits and electrical components and your tips saved me a lot of time.

    Altacliff, I've had this lamp for over 10 years now. No idea who the manufacturer is, I'll pick up the part from a local electronics supplies store.
     
  9. falco84

    Thread Starter New Member

    Mar 11, 2015
    4
    1
    Hi all,

    I replaced the first triac as was suggested and the lamp works like new again. Great site! Thanks all for the advice!
     
    Dodgydave likes this.
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