No Gas welder

  1. rotivator

    rotivator Member

    Messages:
    18
    Location:
    Cornwall UK
    Have now checked the relay and I am getting the 12v across the two points when the trigger is pressed. No voltage on any other pins. Its marked G5LC-14. Does that mean the relay has gone?
     
  2. mike 109444

    mike 109444 Member

    Messages:
    4,069
    uk Bristol
    Set your meter to DC volts, put one meter probe on the pin 1 of RELAY and other meter probe on its pin 4. Make a note of any reading before pulling trigger. Then pull trigger and note any reading. Now keeping the probe on pin 1 move other probe to its pin 3. Note any reading before pulling trigger then note any reading when trigger pulled.
    Make a list thus
    1 to 4 no trigger = ........
    1 to 4 triggered = .........
    1 to 3 no trigger = ........
    1 to 3 triggered = .........
    Can you also make a note of any markings on the transistor that is mounted to the black heatsink.
     
    • pcb 2 UNDERSIDE.jpeg
    • pcb 1 TOP SIDE.jpg
  3. rotivator

    rotivator Member

    Messages:
    18
    Location:
    Cornwall UK
    1 to 4 no trigger Zero
    1 to 4 trigger Zero
    1 to 3 no trigger Zero
    1 to 3 trigger Zero

    1 to 2 no trigger Zero
    1 to 2 trigger 30 v

    Transistor is TIP35C
     
  4. mike 109444

    mike 109444 Member

    Messages:
    4,069
    uk Bristol
  5. mike 109444

    mike 109444 Member

    Messages:
    4,069
    uk Bristol
    If not ebay then RS (if you have one near you. I would have recommended Maplins but they are pants now and don't list a TIP35C, they have others that MIGHT do but just as well to get correct one.
    It is quite a common device so should be no problem getting one.
    Let us know the outcome.
     
  6. rotivator

    rotivator Member

    Messages:
    18
    Location:
    Cornwall UK
    Have fitted new transistor and it's still the same
     
  7. mike 109444

    mike 109444 Member

    Messages:
    4,069
    uk Bristol
    Can you post a clear pic of both sides of the pcb (with the black plastic frame removed) as it is difficult to follow the circuit with the limited pics I have.
     
  8. Appyasme Overhead twin cam 3 phase and neutral

    Messages:
    617
    Location:
    Lancashire
    Sorry Mike.You are bang on about Maplins.If you go into one of tueir outlets and ask for Thyristor the guy will come back with a burger!!!!
     
  9. mike 109444

    mike 109444 Member

    Messages:
    4,069
    uk Bristol
    Sad they have gone that way but even the small electronics shops are gone to.
     
  10. rotivator

    rotivator Member

    Messages:
    18
    Location:
    Cornwall UK
    upload_2015-8-10_19-17-54.png
     
  11. rotivator

    rotivator Member

    Messages:
    18
    Location:
    Cornwall UK
    P8100072 (2).jpg
     
  12. mike 109444

    mike 109444 Member

    Messages:
    4,069
    uk Bristol
    Might be a silly question but have you checked the on board fuse ?
    Where does the bottom connection to the fuse go/come from 9the end nearest the capacitor as it is not clear on the pics. I can see one end goes to the relay pin 4.
    The soldering on D2 looks like it could do with being redone (between the black heatsink and the big green resistor).
    I am drawing out the diagram to try and work it out.
     
  13. rotivator

    rotivator Member

    Messages:
    18
    Location:
    Cornwall UK
    First thing I checked was the two internal fuses. Both ok. It looks like the fuse goes to the bridge rectifier
     
  14. mike 109444

    mike 109444 Member

    Messages:
    4,069
    uk Bristol
    Having looked at both your pcb pic and the other one I noticed there is a blob of solder on one but not the other
    Have you removed a blob of solder that joined the two point at "x x" (linking the tracks for pin 2 and 3) If yes then re-blob. If no then don't.
    If no then desolder one leg of D1 and lift it up. Set your meter to Diode test ( will have an arrow with a line across the point ) then meter across the diode D1 one probe on the pin still left on pcb and one on the "free" pin. Note the reading. Now swap around the meter leads and meter again (so if the meter black lead was on the pcb pin it now be on the "free" pin). Note the reading.
    On a good diode you should see something like 0.400 to 0.600 ish with meter one way round and maybe 1._ _ with meter other way. If you see 0.00 or the 1._ _ both ways then the diode is duff.
     
    • underside 2.jpg
    • pcb 2 UNDERSIDE.jpeg
  15. rotivator

    rotivator Member

    Messages:
    18
    Location:
    Cornwall UK
    Hi Mike Thanks for all your help with my welder. I must say that the level of help you have given me has been exemplary. Its not often that anyone will put themselves out like you have.
    Now back to the welder.. When it first stopped working the wire had run out. When I replaced the wire the machine didn't work. I checked the fuse then the internal fuses. I must have run my fingers over the panel to see if any breaks and I think I did rub a blob of solder off. Anyway I then found that the trigger wire spade had come off. After that you know the story. I was thinking about that solder joint but didn't want to join it in case it ruined the panel.
    I bought this machine a few years ago and its had very little use. I found that while I was playing around with the inside the wiring kept falling apart so its been an experience ! ( I am not technical) Once again thanks for all your help. The blob of soled cured it and I now know a lot more about the workings
    Dave
     
  16. mike 109444

    mike 109444 Member

    Messages:
    4,069
    uk Bristol
    Thank you very much Dave for posting back the result. I do enjoy the challenge of remote diagnoses of faults 9have a few colleges that I have to help from time to time :whistle:) but have been stuck on a site late at night an having help/support at the end of the phone is a blessing.
    Glad you have increased your knowledge of what goes on inside the machine!
    Bit disconcerting that these machines seam so poorly put together as they seam to have much the same level of components as many other "hobby" type machines.
    I will try and post up the part of the circuit I did draw/work out for future ref should anybody come across this post.
     
  17. rotivator

    rotivator Member

    Messages:
    18
    Location:
    Cornwall UK
    Thanks once again
     
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