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Need Hobart TR-250-HF repair advice

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  • ponyracer
    started a topic Need Hobart TR-250-HF repair advice

    Need Hobart TR-250-HF repair advice

    I'm picking up a hobart tig tomorrow, it's an older model, here's what the guy has to say about it.

    "The Machine is a good unit, just needs a little love. I dont know exactly what's wrong with it. The current control circuit has a problem. I fixed a post flow problem a few weeks ago with a ten cent tranststor, so it could be as simple as that. The transformers, high frec. and all the major componets are good, and the unit will weld on a set voltage you just can't adjust the heat. If the price is rite I will let it go with the cables and all. It has a new Weldcraft WP17, 150 amp air cooled torch, new #2 copper ground lead. I have all the schematics and drawings for the machine as well."

    I'll have it tomorrow night, where would you start?? Is it worth trying to repair or do you think it's worth paying someone? I'm a compitent welder with mig/arc/gas and I was trained in tig many yrs ago, we used to train trying to weld soda cans together. I'm somewhat compitent is electrics as well so tearing it down isn't a prob.

    Thanks Phill

    HAHA just found out it's a guy on the board thats selling it. Small world I guess.
    Last edited by ponyracer; 11-01-2007, 07:56 PM.

  • Hobart Expert Keith
    replied
    You can use a .8 ohm 20 watt resistor that is non-fused.

    Leave a comment:


  • shooky32
    replied
    The actual part is a fused resistor (fusistor). Will just a standard resistor actually work without fusing the circuit?

    Leave a comment:


  • Hobart Expert Keith
    replied
    Hobart no longer has parts for this machine. The transistors are I believe 2N3055 and 2N6055 and the resistors can be replaced with 0.8 ohm 20 watt resistors. You should be able to get these or something close at www.digikey.com

    Leave a comment:


  • shooky32
    replied
    Any ideas on these parts? Or maybe a retrofit?

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  • Hobart Expert Keith
    replied
    You are correct. Make sure these are not electrically open. The bottom side is common.

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  • shooky32
    replied
    Originally posted by Hobart Expert Keith View Post
    If the unit is stuck at one amperage output, I would suggest checking the tranistor heatsink assembly. There are 5 transisitors on there. Make sure they are not shorted, especially if the unit is at max current on each range. If at minimum then check the 4 resistors on the side to see if they are open.

    Keith
    I hope I am able to open this thread up again. I have this problem with the amperage being on the low side. Last time we were on the high side, replaced the 5 transistors and all was good. Now we are on the low side as I mentioned, assuming the 4 resistors are the square shaped ones all together shown in the photo.

    the Click image for larger version

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  • ponyracer
    replied
    Yes it welds at max output on each range. Pardon my ignorance but how does one check transistors and where are they located in this machine??

    Thanks for the response.

    Leave a comment:


  • Hobart Expert Keith
    replied
    If the unit is stuck at one amperage output, I would suggest checking the tranistor heatsink assembly. There are 5 transisitors on there. Make sure they are not shorted, especially if the unit is at max current on each range. If at minimum then check the 4 resistors on the side to see if they are open.

    Keith

    Leave a comment:

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