Tradesarc 131i - No weld

  1. KevinMT New Member

    Messages:
    12
    Location:
    Malta
    Dear Experts,

    Would really appreciate your help guys.

    I own a Murex Tradesarc 131i which has currently stopped welding with no welding spark, fan and leds are still ok. Found board 481 847-00IC K-SIDA with faulty 0.033uf capacitor (which is next to the part number printed on the circuit board) and a burnt wire wound resistor which is next to a 2u2 capacitor. The wire wound resistor is so burnt that cant read the resistance value. I have changed the capacitor and the burnt wire wound resistor with a 25K ohms and now I have a spark but very very weak and only one first spark after second ( and following) contact there is no spark.

    Would really appreciate your help on this, about the resistance value and other suggestions to fix this issue perhaps indicating voltage levels of some test point.

    [​IMG]
     
  2. 500e

    500e Always buy fire insurance a flood is hard to start

    Messages:
    4,974
    Location:
    SWest UK
    Have a look in forums welders & welding machine BOC Murex may be something there
     
    KevinMT likes this.
  3. KevinMT New Member

    Messages:
    12
    Location:
    Malta
    Hi 500e,

    Did a quick research on past forums but didnt find any post related with my problem and model number.
     
  4. mike 109444

    mike 109444 Member

    Messages:
    4,302
    uk Bristol
    If you still have the old wire wound resistor it may be possible to measure the remains and work out what the value was.
     
  5. KevinMT New Member

    Messages:
    12
    Location:
    Malta
    I tried to measure the resistor but is giving an open , pressing the resistor gives some value under the kilo ohms but it is varies alot.
     
  6. mike 109444

    mike 109444 Member

    Messages:
    4,302
    uk Bristol
    You will need to scrape off the coating so you can see the wire then measure from one end to the break to get value "X" then measure from other end to other end of break to get value "Y" then add X and Y to get total value of resistor.
     
    KevinMT likes this.
  7. KevinMT New Member

    Messages:
    12
    Location:
    Malta
    good idea, I will try your suggestion tonight. Thank you
     
  8. Bobbes Member

    Messages:
    162
    Location:
    Maarssen / Netherlands
    I see no picture. Can you make a proper foto of the board. The number of the board that you give is a boardnumber without components. There must be an other number on the board and mostly it ends on 0xxx xxx 880.
     
  9. KevinMT New Member

    Messages:
    12
    Location:
    Malta
    I only have this photo but tried Mike suggestion and rating is about 10 ohms. Some wires of the resistor were damaged but very few.
     
    • IMG_20200113_172759.jpg
  10. Bobbes Member

    Messages:
    162
    Location:
    Maarssen / Netherlands
    Exchange the capacito 0,33 uf. This must be at X2 type
     
  11. KevinMT New Member

    Messages:
    12
    Location:
    Malta
    Thanks bobbes I will change the 0.33 uf in any case although the reading seems ok. Is the x2 the type of the capacitor that i need to buy , since the paper capacitor are harder to find?
     
  12. KevinMT New Member

    Messages:
    12
    Location:
    Malta
    With regards the part number of the board I found also this number 481847_ 001c l - sida.

    Thank you all for your support.
     
  13. Bobbes Member

    Messages:
    162
    Location:
    Maarssen / Netherlands
    You need an X2 type because the capacitor C1 (0,33 µF) is used as a ac resistor for controlling the gate of the thyristor. The board number is 481 848 880.
     
    • Stuurschema thyristor.jpg
  14. eddie49 Member

    The "X" rating on a capacitor refers to the voltage of a spike that it can withstand. A type "X" capacitor is typically placed across the AC power lines to filter noise, and a type "Y" is connected from Live to Earth.
    The impulse test rating for type X1 is 4,000 volts ( industrial applications ) and X2 is 2,500 volts ( domestic use).
    For type Y1 it is 8,000 volts, and Y2 is 5,000 volts.
     
  15. KevinMT New Member

    Messages:
    12
    Location:
    Malta
    great Bobbes abd eddie49 thanks. I am going to buy today the wire wound resistor a 10 ohms 10W Aluminuim case , 33nf X2 capacitor 275V & 330nf X2 capacitor 250V.
     
  16. KevinMT New Member

    Messages:
    12
    Location:
    Malta
    The above should be the components that I need to replace, not sure about the wattage of the resistor.
     
  17. Bobbes Member

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    162
    Location:
    Maarssen / Netherlands
    10 Watt is oké
     
  18. KevinMT New Member

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    12
    Location:
    Malta
    Bobbes , can you please confirm the capacitors ratings and resistor from schematics?
     
  19. Bobbes Member

    Messages:
    162
    Location:
    Maarssen / Netherlands
    Oké. C1 is 0,033 µF PME (X2). C2 is 0,33 µF PME (X2). R1 is 18 Ohm 5 W. and R2 is 12 Ohm 10 Watt.
     
    • defecte inverterprint.JPG
  20. KevinMT New Member

    Messages:
    12
    Location:
    Malta
    Awesome Bobbes , thanks
     
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