tshoot transmig 130 twin, wirefeed but no spark

  1. burntdawg New Member

    Messages:
    7
    Location:
    Perth Australia
    Hi All.

    This is my first real post (excluding my introduction post) so please go easy.

    My mig is about 20yrs old, and had a relatively easy life, but recently stopped. Its branded as a CigWeld Transmig 130 Twin - very much a home-handyman design as far as I can tell.

    Observations and actions so far:-
    • Fan comes on
    • Pulling torch trigger will cause wire to feed.
    • Contactor does not pull in when torch trigger pulled.
    • Physically activating contactor - seemed to burn wire that was between the welding terminals.
    • Burnt resistor on control board (was still working)
    • Burnt resistor replaced (3.3 ohm, 7.5W, replaced with 3.3 ohm 10w) - no effect.
    • Reflowed all solder joints on the board to be sure.
    Will follow up with resources I've been able to find, and photos.

    Appreciate any suggestions.
     
  2. burntdawg New Member

    Messages:
    7
    Location:
    Perth Australia
    Manual for the unit - http://www.cigweld.com.au/doclib/manual/Transmig-130-Twin-Operating-Manual.pdf
    Someone's blog post for the resistor fix: http://bodgersparadise.blogspot.com/2012/04/cigweld-transmig-130-twin-repair.html

    Board looks pretty basic. Single layer, through-hole components.

    I see the following passive components: resistors including the large power resistor, 3 caps, the wirespeed pot, and a relay.
    Silicon components:- 2 diodes, a TO220 marked TIC116D, a TO92 marked MPS/A42/M818.
     
  3. burntdawg New Member

    Messages:
    7
    Location:
    Perth Australia
    Ok....after lots of reading and navel gazing, I believe my welder is found in the UK as Cebora 130, Snap-on 130, BOC 130 etc. I might get the forum mod to move it to that sub-forum.
     
  4. eddie49 Member

    Well spotted that your machine is a Cebora 130 etc. clone !
    The contactor is on the output side of the welding power, with all the contacts paralleled-up to handle the current. The operating coil is 240v AC, and according to previous posts on this Forum about the Cebora 130, it is switched by the small relay on the PCB. E.G.:
    https://www.mig-welding.co.uk/forum/threads/cebora-pocket-turbo-130-electrical-trouble.82784/
    I would suggest checking if the relay moves when pressing the torch trigger, open the plastic case and clean the relay contacts, try operating the relay armature manually when powered up. Take care - AC mains on the contacts !!
     
  5. burntdawg New Member

    Messages:
    7
    Location:
    Perth Australia
    Thanks Eddie49!

    After some more navel gazing, i figured the small relay being a mechanical device was worth checking. The relay I have says its a 28V coil so i wonder if there is some minor differences in the circuits. I desoldered the relay and fired it with 24v dc, and it clicked away fine, and there was conductivity through the contacts. Very disappointing as I was sure I was onto something. Back to the drawing board!

    When I get back to the garage, I will power up the board and see what voltage I'm getting to the small relay coil.
     
  6. burntdawg New Member

    Messages:
    7
    Location:
    Perth Australia
    The thick plottens.....

    Checked the voltages on the board on either side of the relay (with the relay removed). Getting 29v on the coil side, 238v on the contact side. Interesting, 29v to the coil came up when i pulled the torch trigger. It didn't go down though when I released. I wonder if that's because the voltage won't bleed down via the multimeter as opposed to when the coil is connected, which would naturally bleed the voltage down. I'm not worried about this at the moment, but mentioning it in case it is relevant later.

    So connected the relay back to the board with some jumpers and lo and behold the contacts are closing. Seems a bit weird - I'm 99% sure these were not closing before when I was first troubleshooting the welder.

    Opened the relay, cleaned the contacts with some fine wet'n'dry paper, went to test the relay and its not working anymore. I guess its possible I damaged the coil, but perhaps it was a bit intermittent all along. Arghhhh. So need to find me a replacement relay, and it seems these aren't that common. Relay markings:

    Finder
    0300
    Coil 28VDC
    Type 40.31SP
    10A 250v AC

    Hopefully someone can help me find a suitable replacement!

    Pics of the relay
     
    • IMG_4564.JPG
    • IMG_6137.JPG
  7. Seadog

    Seadog Forum Supporter

    Messages:
    6,984
    Location:
    NE London - UK
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