Cuircut board problem

Discussion in 'The Projects Forum' started by kevinkhan, Jun 18, 2013.

  1. kevinkhan

    Thread Starter New Member

    Dec 3, 2010
    12
    0
    I have a circuit board and the fuse keeps blowing. also sometimes the thermistor next to the fuse blows as well. What could be the problem and how will i trouble shoot the circuit board. Please see a photo of the circuit board attached. would really appreciate some help.
     
  2. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
    1,190
    156
    Have you tried to search Google for the schematic and work from there ... Also for help we need some basic info like wha
    t is it for and model numbers and such ...
     
  3. kevinkhan

    Thread Starter New Member

    Dec 3, 2010
    12
    0
  4. wayneh

    Expert

    Sep 9, 2010
    12,151
    3,058
    I don't think that's a thermistor. It might be a MOV surge protector.

    Are you sure you're supplying the right power to this thing? Seems like you're trying to blow it up.
     
  5. absf

    Senior Member

    Dec 29, 2010
    1,493
    372
    Was the fuse still blowing if the load (LED lights) is not connected?

    Allen
     
  6. kevinkhan

    Thread Starter New Member

    Dec 3, 2010
    12
    0
    Its a NTC 22D-11 thermistor. And the voltage that is supplied is 230 v.
     
  7. kevinkhan

    Thread Starter New Member

    Dec 3, 2010
    12
    0
    Im not sure about that. Ill check this tomorrow when i wake up. Why do you ask this?
     
  8. apprenticemart2

    Member

    May 7, 2013
    67
    7
    Use your nose.
     
  9. kevinkhan

    Thread Starter New Member

    Dec 3, 2010
    12
    0
    ??? Please only respond with useful information
     
  10. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,999
    745
    Looks like there are 3 separate psus on one pcb, so they can be isolated from the input supply, then if you connect one by one and see when the fuse blows to eliminate it.
     
  11. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    That acutally was useful, often you can pinpoint the bad component by smell. Also please post more detailed photos of both the components and the bottom of the board.
     
  12. wayneh

    Expert

    Sep 9, 2010
    12,151
    3,058
    Ah, it's used to limit inrush current and allow the circuit to warm up gradually.
     
  13. westom

    Member

    Nov 25, 2009
    52
    5
    Most damaged components have neither visual indication nor smell.

    He describes a typical inrush current limiter. Damaged because some other failed part is probably causing excessive current flow. A part causing excessive current and the resulting damage probably has no smell nor visual indication.
     
  14. wayneh

    Expert

    Sep 9, 2010
    12,151
    3,058
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    Visual inspection is a key tool, and smell can occasionally supplement what your eyes are telling you. A big dark circle that smells like phenol is like a red flag. You won't find everything this way, but you'd be rash to ignore the easy signs.
     
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