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98 thunderbolt issue

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  • 98 thunderbolt issue

    Well I had a problem with this old thunderbolt of my dad's. I was teaching myself how to stick weld a few years back and couldn't ever get the hang of it. Tried on a different machine and had no problems. Fast forward to a couple years back and I took the cover off to find out that one side of the shunt had broken off. That is the issue I'm having still. I tried to epoxy it back together and it held for a little while. Even though I got it back together it still never worked to good.
    i would run 3/32 7018 around 120 before I could get any penetration or decent welds. Is there anything that I can do to fix this for good or am I out of luck?

  • #2
    Maybe, but the handicap is the inability to post viewable photos on this forum--biggest tech issue here. Can't really see what's broken. I'm not the guy to explain how to get viewable pics posted, but Oscar, H80N, and others have explanations posted you can search out. Try for a better pic and maybe we can figure it out.


    • #3
      Just looked at my 93 TB ,
      that broken/repaired plastic bridge that supports the adjustment , all thread to position "steel wedge" between primary and secondary has no magnetic flux.
      does NOT affect the performance.

      check the output voltage between low output AC positive terminal and AC negative , open circuit, at idle, should read close to 80 VAC.
      High current terminatal should be 60 VAC.
      DC side should read 72 VDC.
      If not the connections are corroded and or may have some partial shorts in the primary or secondary transformer windings.
      Motors have a similar issue from vibration where the shellac insulation between windings rubs off creating a partial short in the windings reducing the torque of the motor.
      The output voltage of the welding machine is also affected by being subjected to vibration over a period of time.
      The vibration caused from stray eddy currents make the laminations of the transformer vibrate and cause noise( buzz box).
      The constant vibration eventually rubs off the insulation in high contact pressure spots.

      The DC induction choke may also have the same issue as the transformer , but not as likely, since the transformer vibrates inside the cabinet and every other component inside of it. The choke is not rubber mounted, to isolate it from vibration.
      Last edited by Almond farmer; 01-03-2018, 11:01 PM.