SP175T stopped feeding wire

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My SP175T decided to stop feeding wire today. The fan is working, when I pull the trigger the gas solinoid clicks, and I weld voltage at the wire. I tested the feed motor out of the welded and it works fine. There is no voltage at the wire feed motor. I traced the wires back to the board but thats as far as I can go with out some help. Any ideas?
Reply:Check your speed control pot to the pcb. Also check the weld voltage feed back to the pc board. It supplies the power for the motor. If these tests are all good the pc board has failed and will need to be repaired or replaced.The 24 volts from the fan motor is the power supply for the control circuits. working gas valve and weld voltage tells me this is good.
Reply:My miller 175 did the same thing ended up putting in a new board.Millermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:Originally Posted by ccawgcCheck your speed control pot to the pcb. Also check the weld voltage feed back to the pc board. It supplies the power for the motor. If these tests are all good the pc board has failed and will need to be repaired or replaced.The 24 volts from the fan motor is the power supply for the control circuits. working gas valve and weld voltage tells me this is good.
Reply:Pot check is an ohm check to see if the wires and the 5k pot are in good shape and working. See the diagram pasted to the inside of the cover for the wire numbers (208 and 209) and pin (7&1) location in the plug. You want to test at the pot and at the pcb plug. also  find the small wires (203 and 204) that connect to the large cap on one end and the pcb (9&6) on the other end. These two wires are the DC power supply The pcb uses to power the drive motor.To run the pcb electronics it is powered by two wires (211&214) from the fan motor. They pull 24 VAC of a coil in the motor and feed it to the pcb. Nothing works with out this voltage.214 goes straight to the pcb, 211 goes through the over heat thermostat and the trigger  on its way to the pcb becomes wire 213. The gun trigger powers The large relay on the pcb.The relay powers the weld transformer. The gas valve is powered off the 208 line volt tap on the weld transformer. measure the DC voltage on the large cap. should only be there with the gun trigger oulled.
Reply:I'm getting a nice smooth 0 to 4.9 ohms from the pot. All the wires check out and I'm getting voltage from the large cap. Does this only leave the board? Any way to tes the board at the componet level?
Reply:Wires 203 and 204 bring voltage from the weld capacitor to the pcb.The pcb takes this voltage and uses it to drive the wire feed motor.You have weld voltage on the capacitor lets make sure it is making it to the pcb.Find 203 and 204 in the large plug to the pcb. see if you have the cap voltage there when you pull the trigger.539 and 541 are the motor wires at the plug. Make sure you can see the motor with an ohm meter with plug unplugged. Turn the drive roll a little watch for the reading to change.I hope your reading of 4.9 for the control pot is really  4.9K or 4900 Check the multiplier on your meter.Now You have voltage at the cap and weld terminals, that turns on and off with the trigger pull.Speed control pot measure good at pcb plug. Ohm and bench test of motor good.If 203 and 204 have weld voltage at the pcb then the pcb has failed.
Reply:I put a new board in and all was well for about 30 seconds then same thing. This time no power at the cap. BUT I turned the voltage selector switch and all is well now. Does this switch feed voltage to the cap inturn feeding voltage to the board?Last edited by markviiisvt4; 06-29-2011 at 09:17 PM.
Reply:Short answer is yes. A relay feeds line voltage to the transformer. the output taps of the transformer go through the switch to the diode assembly. then to the cap and output terminals. Look at your diagram on the inside of your lid. The voltage switch can get dirty and burnt. some times they can be cleaned and made to work for a while. If it keeps acting up, the switch will have to be replaced. You will need to find a very large soldering iron to replace the switch.
Reply:I've figured out it only acts up on the lowest setting. I took it apart gave it a good cleaning and it works like a champ now. Thanks for all the help.