Announcement

Collapse
No announcement yet.

Bobcat 3 Phase Troubleshooting help.....No Weld Power

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Bobcat 3 Phase Troubleshooting help.....No Weld Power

    I've got a Bobcat 3 Phase. I don't have the complete serial number on me but it is LJ0xxxxx series newer machine.

    It starts fine, idles good. It is generating 115Ac power at the plugs, and the run idle works correctly when you apply power at the plug. The welding output will produce a light arc (enough to burn the tip or stick the electrode) and the machine will idle up to full power but will not weld.

    I have replaced the F1 and F2 fuses.

    I have OCV on the weld outputs of:

    CC + and - of 26.8V
    CV + and - of 26.8V
    AC @ 30V

    The brushes are showing 16V.

    Is there are good starting point to troubleshoot this machine?

  • cruizer
    replied
    Best to us a diode test function on a meter. point ot point on the 4 terminals, will either be open (OL) or have a reading around 0.5Volts

    Leave a comment:


  • Bulldogce
    replied
    I know it is tough online, and I appreciate your help very much. I just like working on them to learn a little before giving up too fast. I switched the C1 cap from another machine, no change. Fuses good, C1 Cap is good, Rectifier good, AC output OK....I feel like I'm down to the Integrated rectifiers or the Reactor

    I want to check the integrated rectifiers SR2 and SR3. What should I be looking for and how do I test them?

    Leave a comment:


  • cruizer
    replied
    Tough one to online T-shoot, best take it into a qualified Miller repair center

    Leave a comment:


  • Bulldogce
    replied
    OK. Replaced rectifier with new rectifier from Miller. Still no weld output.

    Where do I start looking next?

    Leave a comment:


  • Bulldogce
    replied
    Bump. Anybody have a test procedure for the rectifier?

    Leave a comment:


  • Bulldogce
    replied
    BTT

    Anybody know how to test the rectifier?

    Leave a comment:


  • Bulldogce
    replied
    The DC+ AC voltage is 11.8V at run speed.

    If it is the rectifier, any way to repair a rectifier without purchasing a new one from Miller?

    Leave a comment:


  • cruizer
    replied
    whats the AC output at the studs in dC+ mode. I'd say that your rectifier is pooched.

    Not usually a winding issue.

    Leave a comment:


  • Bulldogce
    replied
    DC+ voltage at 28.3v at run position OCV

    Leave a comment:


  • cruizer
    replied
    Whats the DC+ OCV now??

    Leave a comment:


  • Bulldogce
    replied
    Originally posted by cruizer View Post
    Yep freq is WAYYYY low, Must be 62.5Hz high idle no load.
    OK. I adjusted the run speed to 62.6hz @ 126v on the Aux. However, I still have no weld power. It's like welding with 30 amps instead of 150 amps. The rod will arc or stick but will not burn steady.

    Leave a comment:


  • cruizer
    replied
    Yep freq is WAYYYY low, Must be 62.5Hz high idle no load.

    Leave a comment:


  • Bulldogce
    replied
    Aux Power is

    114V @ 58.6hz
    229V@ 58.3hz

    I used some alligator clamps on the brush leads and recorded 23.6V on the brushes. I may have not had a good connection on the previous voltage test. I was a little nervy with my hands down in there with it running.

    Leave a comment:


  • aaronobrien
    replied
    I dont know how close the machines are, but I have a Trailblazer 275 that had the same problem. No repair shop could figure out the problem. I finally decided to try to figure it out....... Long story short, it had a broken rocker arm in the engine. Causing 1 cyclinder not to fire. It would rungreat, all the electrical checked out ok, but once a load was put on it, it would not weld. I replaced the rocker arm and it has ran/welded perfect ever since. Just my 2 cents.

    Leave a comment:

Working...
X