Fixing Burning resistor for LED

Discussion in 'Homework Help' started by parmaja, Sep 22, 2014.

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  1. parmaja

    Thread Starter Active Member

    Jul 2, 2008
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    I am trying to fix my "LEDs with battery emergency light", charged from the main power by using X/Y Capacitor (X Rated)
    http://snag.gy/hac14.jpg

    Here is the part of circuit

    http://snag.gy/TfJYt.jpg

    The problem is the R2 for led indicator of charging, it is burning, i replaced all components except the board, but still burn, this product worked before with me for 2 years before i found it burned 2 risistor, and one transistor, name and values of components written on the board so it easy to replace the damaged ones.

    I Replaced the R2 with more higher wattage but still burn and smoking, the voltage before this resistor is about 22 volt.
    I cant find why still burn, the led replaced twice, R replace to 2k, same.

    Any idea to check what the wrong?.

    Thanks in advance, i am just a programmer fixing my tool with my self, so sorry if i put the topic here with Home work.
     
  2. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,159
    Other than connecting directly to the mains being a topic not discussed here, I do have one question?

    Is your capacitor really 225000 farads?
     
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  3. parmaja

    Thread Starter Active Member

    Jul 2, 2008
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    I replaced the capacitor 225k 400v with another one, same, and it give me 22v, my main power voltage is 220
     
  4. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    225K = 2200000pF = 2.2μF and K is a 10% tolerance
     
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  5. parmaja

    Thread Starter Active Member

    Jul 2, 2008
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    Sorry it is 105K not 225 :p
    but i replaced with the same value, maybe i need to replace it again?
     
  6. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    No, you don't need to do that. Try to add 220Ω/0.5W resistor in series with capacitor.
    And R2 resistor wattage is ? More than 0.25W
     
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  7. parmaja

    Thread Starter Active Member

    Jul 2, 2008
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    I think it is more than 0.25w but idk the value, it is the blue one in the picture
    http://snag.gy/x98u7.jpg

    What the useful for adding 220Ω 0.5w if i can add one resistor for example 1.5k 0.5w, in fact i added it, and burned?.
     
  8. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    LEDs directly from mains is extremely hazardous, as well as against our Terms of Service. Think about using a Wall Wart.
     
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