Newbie needs help.

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Hello. Newbie here. I just bought a Lincoln Weldanpower 250AC/DC-7KW (code:9136). The guy told me if I had a problem sriking an arc to clean the "commutator" with some sandpaper. I have since read this unit has slip rings. Anyway, I cleaned them and took the "shine" off the brushes. No difference. As you can tell I know ABSOLUTELY nothing about the inner workings of a welder. However, I can follow instructions very well. So here are my symptoms.The arc is VERY WEAK. When I try to strike the arc, it doesn't idle up. I put it on high idle and the result is the same-weak arc.So I plugged a drop light into the 110 outlet, barely glows. When I turn the light on, it idles up for a second and then comes back down. I think this is normal since the light is a small load. Just for testing, I turned it up to high idle and got the same results. I checked the output at the outlet and it was 40-50v AC. Can anyone offer an idiot any kind of help? I know I shouldn't have taken the guy's word for it being a good operational unit, but I did. He hasn't avoided my calls, but hasn't offered a solution yet either. Any help you can offer would be overwhelmingly appreciated. I really don't know where else to turn. The nearest service center is a pretty good drive, not to mention, I would like to learn a little about these things so I might be able to stand on my own two feet eventually instead of being at the mercy of the service center.Thanks in advance for all the help.AI
Reply:Bump. Please?
Reply:Avglidot -  I know nothing either, but as soon as duaneb55 shows up, he will sort it right out, I'm sure!-- fredLincoln 180C MIG
Reply:cool, thanks for the update.
Reply:---UPDATE---went and got stone yesterday and used it last night while it was running. no difference.
Reply:Howdy AvgIdiot,There have been several thorough Weldanpower  "walk throughs"  posted, have you had chance to search and review those threads?  Search "Weldanpower +slip" for a few pages of Weldanpower troubleshooting results.Good LuckLast edited by denrep; 11-09-2010 at 11:58 AM.
Reply:excellent. thank you. will do.
Reply:I searched and checked the other threads. So I went and checked a few things.I have 5-6 volts on the brush +resistance between slip rings (with brushes removed) is 5.5 ohmsI noticed F1 (which appears to be the flashing circuit fuse) is a 30 amp fuse. obviously, it has blown in the past. makes me wonder about D2 (field rectifier)I will try and check it tonight (if I can figure out how). I assume I need to remove all wires from it first.I will get a new 8 amp slow blow to replace F1.Not sure what the resistance should be on R4 (rheostat) but it changes as I move the wiper.Slip Rings to ground show no connectivity.Hoping it's the field rectifier (would that cause this?)I checked it with all the wires hooked up and all poles had some resistance between them, which I didn't think is right. Therefore, I will remove the wires tonight and check it again.Any further help would be greatly appreciated.
Reply:rectifier checked out ok. now i'm really at a loss. any ideas?
Reply:Have you got a manual from Lincoln?  That would be a good step.  You might go here and put in your code # and you'll find some manuals to download. http://www.mylincolnelectric.com/Cat...ualsearch.aspxIn the back of the manual are troubleshootung guides which you can read and sort down the problem some.   We have several fellas who are excellent at sorting this kind of issues but they are out of touch apparently... don't quit, keep  watching, an answer will pop up on the WW posts. Another thought, complete the profile for approx where U R, there might be a WW fella right in your area who has more knowledge and can help you figure it out.  Finally these things are not real complex, and it is solvable... ain't rocket science just deliberately shorting huge voltage to ground through chunks of steel under somewhat controlled conditionsenjoy,Lincoln Power MIG 215Lincoln WeldPak 3200HDLincon ProCut 25Lincoln WeldanPower 225 AC/DCIf all else fails... buy more tools
Reply:Good call on the fuse.  Often an owner sticks a larger capacity fuse in place of a blown proper sized one in an attempt to "fix" it.If the 5-6 volts DC at the brushes comes and goes with the ignition switch turned on and off, this would confirm flashing diode D3 is OK.This initial flashing voltage gets things started where exciter winding output takes over and provides a higher AC voltage to that field rectifier D2 where it is rectified to DC and sent on to the rotor thru the brushes.  So, you need to check for AC voltage at the AC terminals of that field rectifier D2 (wires #4 & #5).  No AC voltage means no exciter winding output.   If that's the case, check all connections for the #5 wires (neutral) in the circuit from the stator to D2.If you have exciter AC voltage at D2 AC terminals then recheck D2 for one or more open diodes which is evidenced by no continuity in both directions of any two terminals.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:ok. I will check for the AC at the rectifier. standard 120V?I bought a new rectifier last night so maybe I'll swap it anyway.I was wrong about the fuse. THAT fuse is correct. It is the one next to it that is 30 (F2). That particular diode (D4) seems to be bad though. It has continuity both ways. I THINK it is for some sort of idler control which I am not worried about at this point (unless I should be!)I do have the manuals downloaded. They have helped, but not near as much as reading around on this site!!!Sorry if I didn't follow proper protocol when I joined. I will get that done today.Thanks very much for the help. I will keep ya posted.AI
Reply:AC voltage at the rectifier will be under 120v and in the range of 70-80v at weld speed if I recall correctly.F2 still needs to be correct to properly protect the idle solenoid and circuit.Diode D4 is a "flyback" diode to control or sink voltage spikes when the idler solenoid de-energizes.  If it's bad it will need to be replaced for proper idler circuit/component protection.  Pulling fuse F2 for now to keep the idler solenoid from powering up will do for now.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:ok. I will pull F2I have 6.4 VAC at the AC terminals of the rectifier.For the heck of it, I checked the + - terminals for DC voltage at the rectifier. IT said  900!!! Could that be right? This was all done at "low idle".
Reply:I suspect field rectifier D2 is defective (shorted diode) as an AC voltage will give wacko readings like that on the meter DC setting and an AC voltage to the rotor does nothing for output.Last edited by duaneb55; 11-10-2010 at 11:21 AM.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:FOUND IT!!!!!!!Rat feasted on red wire from rheostat to rectifier. Tied it back together. Voila!!!I found another wire that didn't look to good. Would some plain copper 12-14ga, wire work fine for replacement?Also, any idea what the specs are for that idler diode? I can stop by Radio Shack and grab one but not sure what specs are necessary. Manual doesn't give specs. I've got the slow blow. I bought 8 amp (hope that works).I need to order the insulator for that diode anyway. It is broken in half.Thanks so much for all the help.AI
Reply:Awesome!Match the wire gauge and I'd use a multiple strand wire such as that found in automotive applications rather than a solid wire.Not sure on the diode rating but would guess probably in the 10amp, 600-1200v range.  ??  Is there any identifying numbers on the existing one?  Perhaps the RadioShack guy/gal can help identify it.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:got wires replaced and welding now.new problems though (surprise)i only have 70 VAC at the outlets in low idle. it doesnt auto idle up. if i manually put it in high, i get 120 VAC. before, when i had the other probs, it would momentarily idle up when i plugged something into the outlets, now it does nothing. also, before when i would kill it, it would momentarily idle up then die. now it just dies.the only diodes they had were 1 amp 50V and 1 amp 200V. I tried both neither seemed to work. it was strange, i got continuity both ways but voltage only on one side of the diode. hmmmm. anyway, i tried both and neither worked. maybe i got it too hot with the soldering iron??? dont know. as long as i leave it in high idle, everything is great.is 70VAC on low idle normal?the old diode had no markings on it. it was solid white. shaped more like a bullet than a normal diode. if i can get this part working, i think it will be good as new.please continue the help, i GREATLY appreciate it.Thanks again.AI
Reply:Forgot to get back to you.I don't have an explanation for the change in operation but the next step would be to check out the idler board inputs.1) After starting the unit and with Idler switch in AUTO, check for DC battery voltage at idler board wire #213.  The unit should idle down in approximately 15 seconds.2) Check for AC voltage at idler board wires #3 & #5.  Voltage should match voltage at 115VAC outlets (that 70VAC you mentioned).3) With a load (100watt light) on a 115VAC outlet, check for a low AC voltage (1V+/-) at idler board wires #5 and #218.4) While striking an arc, check for a low AC voltage (1-2V+/-) at idler board wires #216 and #217.If the results of steps 3 & 4 are the low AC voltage at wires #5 / #218 and #216 / #217, the problem is a bad idler board.If no low AC voltage in step 3 and/or 4, one or both current/weld sensing transformers are defective or thier inputs are absent.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Great, thank you.However, small problem. In the midst of looking for parts around town and trying to get help, I ran across a guy who swapped me as is for a 2003 Miller Bobcat 250NT 10kw with 1800 hours. Kohler engine. Everything on the Miller works great. With the exception of the noise difference (which I expected) I like it a lot. Sure hope I didn't get screwed!BUT before he took it, I tried one last time to get the auto idle to come up. I turned the outputs all the way up and struck an arc. I maintained it for SEVERAL seconds and it came up and stayed up while under load. However, I tried it again and again and again and again and again. Never could get it to do again.Thank you 1000 times over for all the help.AI