MIG wire speed control problems

Hi all:
I am trying to repair the wire speed control on a Century welder Model
83132. The control has a very short usable range and past position 4 is
faster than 700 IPM, so it is almost impossible to "tune it in". Is there a
place where I can buy a pc board for this unit or get a schematic of the pc
board with the parts values. I don't think the Century factory keeps parts
for these old machines. Who owns Century now? I called the support
number and somebody from Lincoln answered. BTW, I know that I am going to
get the advice to throw the Century away and get a Red or Blue machine.
Well, I am seriously considering buying the Millermatic 210 or a similar
machine. Any suggestions?
Thanks for your response
Best Regards,
Ray Ramos
Reply to
Rafael Ramos
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Hello Ray, Have you checked the potentiometer that controls the motor speed? Maybe it is dirty. Unsolder the wires to the potentiometer and use a multimeter on the ohms range to check that the wiper contact of the potentiometer changes resistance smoothly when the shaft is turned smoothly, measuring between wiper and either end of pot. with the ohmmeter. An analog meter with needle pointer is best for this test.
Look for loose and dirty connectors on the motor control board. Tighten up/clean any connections that look dodgy.
Obtaining a schematic would be ideal, then repair would be easy but don't give up on that idea yet, keep looking. In the mean time you could isolate the two motor connections and build your own speed control in a separate box for less than $20 in parts.
Google motor speed control There are lots of schematics to choose from.
Here is the third hit down
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are details of a kit.
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I prefer the first link above because it is important to find a good quality wire wound potentiometer. The ohmic value of potentiometer VR1 is not critical in the solor circuit above. You can find a good quality wire wound pot. in your junk box (or friends junk box) or from junked equipment and use it. Any value between 1000 ohms and 10,000 ohms will be fine. You just have to reduce the values of R6 and R7 accordingly. Better still, make R6 and R7 trimpots. Having found a good quality pot for free, the rest of the components are peanuts in dollar value.
Once you have built a speed controller and got your welder functioning again you can take your time finding the Century schematic and repairing the faulty Century board. Just a suggestion.
Regards, John Crighton Sydney
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Reply to
John Crighton
Thanks John, Now I have done some of what you mention and everything seems to work ok, the pot is nice and smooth (with analog voltmeter) and the board checks out OK. There is a nice big elecrtrolitic capacitor filtering the 24 volts that looked bad, the positive side looked black and some sort of film on the outside, I unsoldered it and measured and it was OK too. I am certain that the problem is in the wire feed mechanism. There is only one active wheel that is pushing the wire and I think it is encountering changing pressure from the wire spool when trying to spool the wire out.
I am now looking at better and more powerful mig machines and plan to purchase a new welder in the very near future. The old Century will be relegated to an experimental machine that I plan to modify and learn details of the mig welding circuitry.
Thanks again for your very informative reply. I plan to use the information to start my files on how to do the modifications.
Best Regards,
Ray
Reply to
Rafael Ramos
Ive been having a somewhat similar problem with my old Dan-Mig 200.
Wire has been hit and miss..get a good arc going..and it would spit and sputter. and it turned out to be an old and tired liner.. Id been given some liners that were the right length and ID..but the fitting on the end was too big.
I stuck the liner in the lathe, ran the length into the bar feed tube and turned it down to the proper dimensions. Old bitch runs good again. I can now put a fairly sharp bend in the gun cable and it will still feed just hunky.
Gunner
"The importance of morality is that people behave themselves even if nobody's watching. There are not enough cops and laws to replace personal morality as a means to produce a civilized society. Indeed, the police and criminal justice system are the last desperate line of defense for a civilized society. Unfortunately, too many of us see police, laws and the criminal justice system as society's first line of defense." --Walter Williams
Reply to
Gunner
Hi Gunner:
Thanks for your reply. You brought out a good point that I had not considered, and could very well be the culprit. I will check the liner and the rest of the gun past the driving wheel and make sure there are no obstructions and the wire has a free flow through it. I guess a liner is available and probably not too expensive so I will order one Monday just in case. I'll let the group know the results. Lincoln is now the owner of Century welders and they have most of the parts available for this welder . I am now at a point in my mig welding that I am seriously considering an upgrade to the big players, I am looking at the Miller 251 and the Lincoln 255. Yesterday I stopped at Intermountain Airgas and General Air and looked at their machines. If I solve the problem with the Century I will not have an excuse to spend all that money for a new welder, but it would be great to solve the mystery, and I can always find another excuse for the purchase. Thanks again for your advice.
BTW, I enjoy reading your postscripts.
Best Regards,
Ray R
Reply to
Rafael Ramos

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