Cyber Tig problem. Turns off for no reason.

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Hello everyone. I have a Hobart Cyber Tig 300 and it has a problem. After welding (I usually use the 3-100 amp tap, but the problem happens on all taps) for about 20 seconds or so the arc will stop. It I press the pedal I only get the high frequency start, but no stable arc. If I let the welder sit for about 10 seconds or so I can get an arc and weld again for about 20 seconds or so before the problem repeats itself. I have stopped using the welder because i don't want to hurt anything. This happens if I weld at a low amperage or at a high amperage. What should I look for? When it is working it welds GREAT. So far I have only checked to see that the work cable was tight at the machine and at the clamp, both connections are great. Thanks for your help.Hobart - CyberTig 300CTHobart - IronMan 210Lincoln - WeldPak 3200
Reply:Did you you take up your question with someone at Hobart?http://www.hobartwelders.com/service/ How about the Hobart board?City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:I have not contacted Hobart by phone or e-mail yet, I was hoping one of the old timers (No offense) on the boards would have a few suggestions first. I have posted a question on the Hobart board. There is 1 reply so far on the Hobart board but he had a question about the circuit the welder is wired to. The circuit is big enough to sufficiently feed the welder so that is not the problem. Any other suggestions?Hobart - CyberTig 300CTHobart - IronMan 210Lincoln - WeldPak 3200
Reply:As I already told you on the Hobart board.Feed that sucker about 110Amps @ 240 volts and the problem will go away.I'd bet dollars to donuts it's not getting adequate input amps.  Those old transformer machines need lots of power, even when operated on lower output settings.What size cord do you have it hooked up with?Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:I didn't know that was you on the other board. The welder is on a dedicated circuit. The data plate states that the welder draws 96 amps. It is on a 100 amp breaker in a sub panel and fed by 2 AWG wire. The welder is hard wired into the wall. That should be more then enough power. Any other suggestions?Hobart - CyberTig 300CTHobart - IronMan 210Lincoln - WeldPak 3200
Reply:have you run this machine in the past? if not i would have to agree with sundown III. i would like to see a little higher leeway on the current supplied. you are only feeding it 2 amps more than the manuf. recommends. there is a lot of misconseption when it comes to welding and lower amperages and the size breaker used. too many people think that just because they are welding at lower amperage they can get away with a smaller breakerMillermatic 211weldpack 3200 squirtgunsquare wave 200victory journeyman kitHypertherm 30xptoo much other crap to listtinkerer extraordinaire
Reply:The idling current on a machine like that may be high, so the current draw even at low amp output will still be relatively high, but it should be nowhere near the full primary current draw at 30% or even 50% output unless something is wrong with it.Assuming it's not a new machine, I would disconnect the power, open the case and look for layers of dust or grit which could be allowing current to leak. Also look for loose connections inside. If it has lots of modern control circuits (I don't know the unit at all), be careful about damaging components of the boards with static electricity while examining/cleaning them. I would wait to talk to a company rep. if nothing is obvious if/when you open the box.
Reply:100amp circuit should be more than adequate, but I'd try out the machine on a different circuit just to be sure. If there's still a problem, here's an excerpt from a Heliarc 350 manual on troubleshooting (I know it's not the same machine, but the chart's pretty generic so it's applicable).Erratic output welding current.1. Intermittent shunt connections. Check connectionsto shunt.2. Defective SCR and/or diode in main bridge. Seetroubleshooting 3-b and 3-c.3. Defective SCR p/c board. Replace SCR p/cboard.4. Excessive high frequency. Check spark gapsand adjust if necessary (see Maintenance Section).Check all connections and components inhigh frequency bypass circuit and replace anydefective components.
Reply:I would check the machine under load.   Start at the input.  Put a volt meter on the power in and see if it drops off.  After that, keep going towards the transformer, power in and out, then diodes until you end up at the output.  Somewhere it has to have a poor connection or failed part.  Maybe the power switch?It has to be checked under load.HERE WE GO WITH THE DISCLAIMER.  ONLY DO THIS IF YOU ARE CONFIDENT OF YOUR ELECTRICAL SKILLS.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Ok, stupid question, have you checked the settings on the machine to see if maybe you have the weld timer set for a 20 second weld?  Some Cybertigs have a spot weld timer, and others have a complete weld sequence timer with settings for preflow time, initial current, upslope time, weld current, weld time, downslope time, final current, and post flow time.
Reply:one thing to help isolate the problem- turn HF off, turn the remote/pedal switch off (so the torch is just always hot at whatever the dial setting is)  and scratch start it, see if it works continuously. This will rule out anything funky with the pedal/control transformer/hf circuitry.
Reply:oops double postLast edited by Capnbondo; 08-18-2008 at 06:52 PM.Reason: double post
Reply:OP thinks he's found his problem.  Posted his findings on Hobart Board.Bad circuit breaker was dropping one leg but not tripping.  Replaced breaker.  Seems to be running fine.Those old Hobarts are tanks, but you gotta feed them "high test" input amps.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.