Hobart 250 Stick Welder

   / Hobart 250 Stick Welder #1  

Steve_Miller

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Anyone ever work on the electronics on one of these? It's at least 20 or 25 years old.

Steve
 
   / Hobart 250 Stick Welder
  • Thread Starter
#3  
This is a back burner project, I just came across it again the other day. The welders told me they had to keep turning their heat up to the point they cannot weld with it anymore. We sent it to our local welding repair shop and they said it was going to cost upwards of $2000 to repair so it's been sitting here ever since and I thought I would take a look at it for a home welder if it wasn't too expensive a fix. Does anyone have any info on a TR250 ac/dc or do I need more info? It is probably 20 to 30 years old but I can't imagine it being $2000 to fix. I did join the Hobart forum but have not been authorized to post yet.

Thanks
Steve
 
   / Hobart 250 Stick Welder #4  
Let me start by saying I have no idea what is inside your Hobart stick welder, but I am guessing that 20 25 years old, there are no complicated "electronics" inside, just "electrics" in other words, transformer, rectifier, chokes, and capacitors. and of that group, the most likely to fail are rectifier diodes, and capacitors. diodes most likely fail by shorting out, and caps fail mostly by going open from drying out. of course they can short out also, but the failure mode you describe sounds to me like an open cap. You can test them with an analog Volt Ohm Meter (VOM) by taking a known good cap with the same capacitance rating and placing the leads on each terminal and noting the "kick" of the meter (goes to low resistance them falls back to high) in a certain time period. and then testing the suspect cap and noting its kick if any. reverse leads and test again. reverse it again and test again. Testing in this manner is subjective, you must get a "feel" for the action of the suspect cap as compared to the know good cap. if it does not kick, but shows a constant resistance, it is bad. if is shows shorted, bad if it shows open both directions it is bad. The alternative is to get a real capacitance tester, but they can cost some money. But by testing with the VOM and just a few minutes to educate yourself as to what to expect, you can do a fair job of deciding if the cap is bad or not. Chokes should show as a low resistance. Chokes with the current ability I would expect in a welder would show pretty much as a dead short to a VOM. maybe 1 or 2 Ohms. Also while in there I would check out any switching contacts, for burned look, and contact resistance (should be a dead short). So there you go, I would tear into it myself, and have a look, you have nothing to lose. Oh, you may be able to get parts at either Mouser or Digi-Key, good luck
James K0UA
 
   / Hobart 250 Stick Welder
  • Thread Starter
#5  
I made another attempt at this welder and found it was a Mega Arc 300, not a TR250.
I just made four phones calls and read somewhere on a website which I cannot find again and here is what I found out.
First of Hobart Brothers was bought by ITW (Illinois Tool Works) in the 90's. Becusae they (ITW) would have had a monopoly on 250 amp and above welders, they were not allowed to keep that part of the business and it ended up in the hands of Thermal Arc. So anything 250 amp and over you can call Thermal Arc at 1-800-462-2782 and they (i hope from what they said) are going to send me an email copy of the manual with troubleshooting and schematics of my Mega Arc 300 (spec # 6035A-1). Hope this may help anyone in the past or future.

Thanks
Steve
 
 
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