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Resistor Advice

Discussion in 'Troubleshooting and Repair' started by diabolus, Jul 1, 2013.

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  1. diabolus


    Jul 1, 2013
    Hello, I would be very grateful if someone could help me out with some resistor advice.

    Basically my electric welder was knocked over and stopped working. I opened it and found what seems to be a burnt out resistor. It's not a type of resistor familiar to me. This resistor (photo titled 'old.jpg') is a coil of thin wire around a chalk (or some sort of fragile ceramic) core. I googled variations of the characters printed on the component but could not find any information. The characters are as follows:
    AT 7CS
    478 J 2008
    So I rang the local electronics shop and after I described the part and read out the code I was asked to bring the part in because he didn't have a clue. I was at work so my wife brought the part to him. He gave her the resistor in the photo titled 'new.jpg' and said "give it a try, it'll probably work". That doesn't leave me with a lot of confidence... If anybody here can confirm whether this part is suitable or will cause more damage than has already been done I would be very grateful :) The code on the new resistor is:
    210-9 47R
    202-3 5% e

    Attached Files:

    • old.jpg
      File size:
      136.3 KB
    • new.jpg
      File size:
      136.3 KB
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    For power resistors, the physical size and weight is related to the power handling capacity. Is the new one similar in size?

    Also, you're in luck that the original part has such obvious windings that you can probably measure its value.

    Get a multimeter and place one probe on a lead of the resistor and with the other one poke around the burnt out section until you find a position that reads some resistance. Do this again for the other lead. Then add these results together. The value you get here will likely be within 10% or so of the original rated resistor value.

    As long as the replacement is fairly close to this value (say 20%) then you should be fine. (I say "should" not knowing what the resistor is actually used for).

    Getting a measurement of the actual value of the resistor and a photograph of them side by side would be useful.

    Also check to see if there are markings on the board which indicate the resistance.
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