MIG wire speed control problems (2023 Update)

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
Loading thread data ...

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

formatting link
are details of a kit.
formatting link
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

*** Posted via a free Usenet account from
formatting link
***
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

Hey gang, I read this thread in hopes of finding the cure to my issue (which is similar). Got a Craftsman (Century) from 1992. First time in years I’ve used it and I’ve noticed the wire feed is slow AND weak. I can literally stop the wire feed roller with my fingers (and reasonable pressure) on full speed. I’ve replace the gun, liner, and everything recently because the old one was just too stiff. I also did so in hopes it would solve the feed issue… nope.

I’ve tested the motor on a 12v battery directly and can see that it and the gearbox are working fine - torque and speed. It was hauling ass and I couldn’t stop it with the same pressure as before. I spoke to someone at Lincoln (who now owns Century) and was told the board is likely not putting out the amps the motor needs for proper torque. I just bought the board, but don’t want to throw parts at it. I know something isn’t putting out the right amount of juice and I’m trying to figure out where it’s NOT coming from. Does this make sense to anyone else? I know things get old and stop working, but like the others, I’m not familiar with circuitry and and reluctant to just throw parts at it. I love this welder and really want it to work.

Thanks in advance for the knowledge.

-Jason from Denver.

Reply to
Thesykboy

Hey gang, I read this thread in hopes of finding the cure to my issue (which is similar). Got a Craftsman (Century) from 1992. First time in years I’ve used it and I’ve noticed the wire feed is slow AND weak. I can literally stop the wire feed roller with my fingers (and reasonable pressure) on full speed. I’ve replace the gun, liner, and everything recently because the old one was just too stiff. I also did so in hopes it would solve the feed issue… nope.

I’ve tested the motor on a 12v battery directly and can see that it and the gearbox are working fine - torque and speed. It was hauling ass and I couldn’t stop it with the same pressure as before. I spoke to someone at Lincoln (who now owns Century) and was told the board is likely not putting out the amps the motor needs for proper torque. I just bought the board, but don’t want to throw parts at it. I know something isn’t putting out the right amount of juice and I’m trying to figure out where it’s NOT coming from. Does this make sense to anyone else? I know things get old and stop working, but like the others, I’m not familiar with circuitry and and reluctant to just throw parts at it. I love this welder and really want it to work.

Thanks in advance for the knowledge.

-Jason from Denver.

---------------------

Posted to sci.engr.joining.welding

The schematic for a Century Powermate 70 shows two apparently selenium rectifiers, a speed control pot and the torch switch in the wire feed motor drive. Any of them could be the problem.

-jsw

Reply to
Jim Wilkins

A wider overall point:

With a MIG / GMAW welder, you deliberately set the drive rolls so they will skid if the wire jams. You set the pressure so the wire will feed, but any more resistance than regular feed and the rolls slip on the wire. That's the reason for the springs on the toggles mechanism for the drive rolls.

Reply to
Richard Smith

The problem is, there doesn’t seem to be enough amps to the feed motor to power it with the torque it needs to move the wire. I’ve run the wire through 2 different liners and the resistance in the feed is the same. So I’m guessing the motor has to have a bit of torque to feed the wire.

Last night I tested amps where the leads come from the board to the motor. When the pot is set at 2, it reads .26 amps. When I keep cranking it up to 6, it hits .30 amps, and at 8…. same .30 amps. I’ve looked at other motors online to get a baseline of how many amps that motor should need to do its job. Even the cheap ones on Amazon are doing .90, so I’m thinking the amps coming from the board are way too low. I found a company that sells a new OE board with pot and voltage dials on it for a decent price. I don’t want to just throw parts at it, but in my research so far, everything points to what is sending amps the the motor… the board.

Sound about right?

Reply to
Thesykboy

The problem is, there doesn’t seem to be enough amps to the feed motor to power it with the torque it needs to move the wire. I’ve run the wire through 2 different liners and the resistance in the feed is the same. So I’m guessing the motor has to have a bit of torque to feed the wire.

Last night I tested amps where the leads come from the board to the motor. When the pot is set at 2, it reads .26 amps. When I keep cranking it up to

6, it hits .30 amps, and at 8…. same .30 amps. I’ve looked at other motors online to get a baseline of how many amps that motor should need to do its job. Even the cheap ones on Amazon are doing .90, so I’m thinking the amps coming from the board are way too low. I found a company that sells a new OE board with pot and voltage dials on it for a decent price. I don’t want to just throw parts at it, but in my research so far, everything points to what is sending amps the the motor… the board.

Sound about right?

------------------------------

A partly open bridge rectifier diode will give you the no-load voltage but not the full current. Half-wave rectification is obvious if you have an oscilloscope. It might show up as a large voltage difference between when the motor is connected and disconnected.

If you can find an electrical schematic for it I might be able to suggest other tests to locate the fault.

Reply to
Jim Wilkins

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.