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Duratech 5 Diopter LED Illuminated Magnifying Lamp : Burnt resistor

Discussion in 'Troubleshooting and Repair' started by Majorphill, May 27, 2017.

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  1. Majorphill

    Majorphill

    5
    2
    May 27, 2017
    Hi

    I have one of these with a burnt resistor (the only one).

    I am unable to read the bands and can not find a circuit diagram.

    Does anyone know what it may be or alternatively who manufactures the Duratech brand so that I can ask them direct.

    Thanks in advance
     
  2. davenn

    davenn Moderator

    13,502
    1,830
    Sep 5, 2009
    post a photo or link to one so we can see the one you are talking abt
    it may be the same as one I have here and I can open it up and look for you
     
  3. Majorphill

    Majorphill

    5
    2
    May 27, 2017
  4. davenn

    davenn Moderator

    13,502
    1,830
    Sep 5, 2009
    OK looks real similar to mine ... it came from Altronics instead

    so do you have a photo of the circuit board so I can see if it is the same and which resistor you are talking about ?


    Dave
     
  5. Majorphill

    Majorphill

    5
    2
    May 27, 2017
    Dave
    The item is at my workshop. I shall take a photo today and post this evening (Ausralian Time).
    It could well be a generic bran marketed under many names.... Duratech, Velleman, Rhino etc
    Thanks for your help
    Phil Major
     
    davenn likes this.
  6. Majorphill

    Majorphill

    5
    2
    May 27, 2017
    Dave

    Here we go. As you can see my photographic skills are not great.

    The area to the upper right had the blown resistor.

    I suppose the next question is why it blew. I had been using the light for an hour or two when the LEDs went very dull.

    Again

    Thanks for your help

    Phil Major

    765.jpg 766.jpg
     
  7. davenn

    davenn Moderator

    13,502
    1,830
    Sep 5, 2009

    slightly different to mine but basically the same process
    240V in phase through a fuse inside heatshrink ( lower left on your first photo)
    mine doesn't use that large input capacitor, tho there is holes in t he PCB where it could go

    then mains goes to a bridge rectifier ... probably under that large cap on your board.
    the output of the bridge rectif has an electrolytic cap across it, mine is a 2.2uF 400V rating
    you one looks like the cap is bulging at the top and is close to blowing --- it may be the main reason for the overall failure
    mine doesn't have that resistor in the output, tho again there are holes in the pcb where it could go

    The ring pcbs that have the LEDs on them have a number of 1W 900 Ohm resistors
     
  8. Majorphill

    Majorphill

    5
    2
    May 27, 2017
    Dave

    You are a gentleman :)

    Thanks for that.

    My light doesn't work without the resistor and barely worked with the blown one in.

    Maybe I'll take a punt and replace the missing one with another 1W 900 Ohm resistor. I can't do more than keep it not working. :rolleyes:

    I noticed the cap looked swollen as I posted the photos but didn't notice it when I was looking at the board. I shall look more closely tomorrow. I shall look for those ring pcbs.

    This is a great resource and I am going to be an avid follower as I try to learn a little more.

    Many thanks

    Phil Major
     
    davenn likes this.
  9. bradmaarssen

    bradmaarssen

    1
    0
    Feb 26, 2020
    Did you have any luck with your lamp? I have the same one with the same problem.
     
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