Lincoln Problem

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Hi, I am mike and I am new here.I have a weld-pak HD that has been working great for the last 10 years.  I was using it yesterday, and after a while the thermo protection circuit came on.  Once I let it cool off, the welder was dead.The fan comes on, but there is no wire feed and no arc.  I replaced the contactor but that didnt help.  I also bypassed the thermo switch, and checked the continuity on all the switched, and it all check out.   So that leaves me with a possible circuit board.  Does anybody know how I can bypass the board temporarily to see if thats the problem.   Or is there a way to test the board?
Reply:My Weld-Pak 155 has a reset button. It's at the top of the wire drive area, above the feed rollers. I'm assuming you found, and tried resetting that button.PapaLincoln Idealarc 250 (circa 1962)Lincoln Weldpak 155 w/Mig KitLincoln Squarewave TIG 175
Reply:Mine doesnt have a reset button.  It doesn't have any fuses either.
Reply:Does anybody else have any suggestions on what to check on this machine?  I really dont want to have to buy a new one, but I also dont want to throw a bunch of money at this one only to have to replace it anyway.
Reply:You didn't say which one you have... is it the 110 or 220 volt machine? If you get the serial number and code number off the machine, you can download the schematic. If you share that info with us, we can help track down, and isolate the problem. I was an electronics tech by trade for 25 years or so. If you don't already have one, get a half decent multimeter for troubleshooting with.PapaLincoln Idealarc 250 (circa 1962)Lincoln Weldpak 155 w/Mig KitLincoln Squarewave TIG 175
Reply:Its a 110v weldpak HD code number 10949.  I have a nice multimeter from being an electrician and will try to get a schematic.
Reply:I tried blowing it out with compressed air just to see if it would do anything, it didnt help.  At this point I am just going to try to delete the circuit board.  I figure if I can get the trigger to engage the contactor, then get the contactor to turn on the wire feed and the transformer, then I can probably work with what I have.  If that doesnt work, then I am just going to get another one.  I will probably end up buying the same one I have, since its only $269 and has worked well for 10 years.
Reply:Check two things, Check the trigger wires to the weld tip and make sure they are not shorted. Lincoln magnum 100 guns have a bad habit of pulling apart at the drive end,Remove the gun from the welder. short the trigger plugs and turn on the welder output. Use the volt meter and measure for DC volts at the polarity studs. If you have volts, your gun may be bad. If no volts, find the cooling fan. It has 4 terminals. The 2 large ones are line power and the 2 smaller ones are 24 volts AC. This 24Vac powers the pcb through the miggun trigger circuit and the thermostat. Get your meter and follow the 24Vac  from the fan motor to the pcb. Before you declare the pcb dead. Make sure it is getting all it's voltages. You have line voltage, 24Vac trigger, And weld voltage. Find the large capacitor on the diagram and make sure the wires from there to the pcb are good. The 24Vac runs the pcb and the weld voltage is the power for the wire drive motor.
Reply:Cool, thanks!
Reply:One more thing look at the diagram pasted on your cover. Use it as a road map.
Reply:I asked a Lincoln rep and he said, "The best way to figure out what your problem is would be to measure your output voltage.  You wire feed motor is powered (through the control board) off of the actual arc voltage.  If you have voltage between the positive and negative stud while you hold the trigger (around 25VDC), then chances are you have a bad control board.  This can be tested and replaced at any of our local service facilities.  If you don't have any voltage, then try to switch the voltage selector knob to each position and try to feed wire again.  Sometimes the selector switch will get stuck between two taps and you will then lose welding voltage.  If there is still no wire feed, then you may have a bad board."Good luck on your repair.