Help, No DC Welding current on Ranger 8

admin

I have a ranger 8 model 10535 with no DC + or DC- or CV current output.   I have good AC generator output and good AC welding current on all settings.    Can anyone advise me what to test/check to figure out what might be wrong  thanksDJTiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:Sounds like you might have a fried rectifier stack. That would be a common denominator to all three dead outputs. That's just a guess though since I don't have a schematic for that machine.CV is for wire feed welding, and that's DC output, along with DC POS and NEG for SMAW.GregLincoln Idealarc 250 (circa 1962)Lincoln Weldpak 155 w/Mig KitLincoln Squarewave TIG 175
Reply:Update,   I took the sides off and just cleaned it up and tested for the appropiate voltage.   I get good DC Voltage between 35 and about 65V DC when I rotate the fine current adjustment Knob on bot CV and all DC amperage settings. So I guess that is called the open circuit voltage with correct DC electrode Pos and Neg with the engine at full throttle.   Still don't get any welding Amperage/Current Hoping someone can help me narrow this down as to the causeThanks in AdvanceTiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:DJ, Where did you probe for these voltage readings?PM me an email address.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:Hey there Dwane,   I worked on it for a few hrs tonite.   started by swapping the rectifier diodes with the ones in my Miller Dialarc 250 as I knew those were good.   had same result and the dialarc welded DC fine with the Lincoln diodes..   Fortunately having the Miller machine I was able to compare readings.   Knowing that it was fine at least past the diodes, the only piece of the puzzle left was the Choke.   checking the resistance across the two terminals of the choke gave me something like 7K ohms resistance which seemed real weird for a continous piece of aluminum.   also had 4K ohms to the steel housing for the Choke...   I knew it was supposed to be isolated and the miller choke had perfect 0 ohms continuity with the same test between the two terminals.   removed the choke assembly and saw what looked like solder... actually melted aluminum on part of the inner coil of it.   after staring at it a while i realized the entire Choke coil had shifted inside the housing about 3/8 of an inch.   so  placed the frame on some metal supports and tapped the coil back through the housing.   sure enough the coil had contacted the housing burning and melting part of the inner coil.   now at 4K ohms resistance between the 2 ends of the choke.  cleaned and wire brushed the burn area and finally got back to 0 ohms...  Have not installed it back in machine to see if it works yet but that was definitely the cause of the problem....  Just thought it was a really weird issue so explanation was in order.     Not sure if its gonna work properly due to the melted section and the current may remelt it or jump across the coil not going around the proper path.   Not really sure what the Choke does so will just try and see what happens. I think it has something to do with stabilizing the DC waveform or current, right?  will call Monday and see on a price for a new choke though I am sure its outrageous..   Wonder if anyone has a spare from an otherwise parts machine...Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:Believe it or not that's where I was headed (the choke) and the reason for my asking although I was suspecting a bad lead connection.And yes, the choke serves to stabilize or smooth out the output current.Good troubleshooting. 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:Choke coils have different applications, but I was going to suggest a high resistance connection after you said you had voltage, but no weld current. This is the same as a bad connection on your car battery. It will measure 12 volts at the battery, the dome light will work, but it sure as heck won't put out enough current through that connection to turn the starter motor.Glad you traced out the problem. Hopefully it will work okay and not melt down again.Lincoln Idealarc 250 (circa 1962)Lincoln Weldpak 155 w/Mig KitLincoln Squarewave TIG 175
Reply:Thanks.  I did stop by the repair shop earlier and got some explanation of how it all worked and some pointers on the wiring diagram I took with me.  He did explain that its probably not a PCB issue as the DC works off of the AC so if I have AC welding current then the PCB is already getting all the correct signals...I am a master auto tech so I am good with the auto electric diagnosis but the AC stuff I am far less versed in.   Though after getting the info from the repair shop I had a better understanding of what was going on... thanks for the help.  Now where to find a good Choke at a decent priceEDIT:  I do have a lab scope so being its DC, I can check the actual waveform if I get it working and I found the service manual online with examples of the waveforms.    So if it does work I can see if its messed up or not.Also hoping I can run the Miller wire feeder I got off this Ranger.  I guess it will be always hot for the gun but I think I can live with that.  Already wired up a 110V ac plug to the wire feeder.Last edited by soutthpaw; 04-09-2011 at 12:12 AM.Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:got it all back together and working like a champ now.  also did full service on engine and carb.     Not a bad deal for $600 via CraigslistTiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:Got the Choke switched out with the parts machine I bought monday.   now it runs the wire feed in CV much smoother.  really didn't notice a problem with CC mode DC with the old Choke. it was only on the CV mode that it didnt seem to run smooth.Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:Awesome.  Good job and thanks for the update.Happy welding!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!