MM200 drive wheel

[Sheryle]

I have a MM200 ser. # JG088367 that will not feed the wire. I call it a drive wheel(the bottom one of the two) does not turn when I press the trigger. I have two guns and they both work on my MM250 but not the MM200. Any direction, advice or comments welcomed. I am a complete novice with these welders. My only experience is with stick and that was a long time ago. Thanks

BTW! I am not going into the welding business, I just got these 2 and a MM35 in a truck trade.

[duaneb55]

If you don't have it yet, go here http://www.millerwelds.com/om/o1303k_mil.pdf to download the MM200 unit manual to have for reference and troubleshooting.

Does the pilot light on the front of the machine come on? Does the contactor activate when you pull the gun trigger? If not, check fuse F1 for being blown.

If the pilot light comes on and the contactor doesn't activate, check for a bad control relay CR1.

Check those typical simple things out first and we can go deeper from there as needed.

[7A749]

Duane knows these machines well. He can most likely walk you thru any problems you have.

If you need a motor control board, I have plenty of good used ones

[Sheryle]

Thank you both for replying.

If you mean owners manual, I have downloaded that and read through parts.

As for lights there are no pilot lights on either machine, Bulbs probably need replacing.

I have pressed all 3 circuit breakers, one by the wire drive and 2 on the front, I don't hear or feel a click(reset sound). Should I?

How would I check the contactor? Hopefully something visual because I don't hear very well.

[duaneb55]

Per your unit SN, the manual shows it still being equipped a fuse above the pilot light so with three circuit breakers, the manual link isn't correct.

Does the machine have a 4-pin or 14-pin receptacle for a spoolgun hookup? We need to establish exactly which generation machine you have so we can refer to the correct control circuits.

Do you have a volt/ohm meter? If not, you're going to need one even if it's a $5 cheapy.

[Sheryle]

Okay I confess. I was looking at the drawing in the manual I downloaded when I said I had tried to reset 3 circuit breakers. I went back to the MM200 and it has a circuit breaker inside by the drive assembly and a fuse on the front. BTW the fuse appears to be good. I promise to look at and work on, only the MM200, if you will continue to help me, please. By trying to compare one machine to the other I see that I am comparing apples to oranges or at least red delicious to winesaps. Confusing myself and most of all giving you the wrong information.

Also to answer your question the spoolgun receptacle has 4 holes.

I have a multimeter, IDEAL brand that I mostly use to check voltages. It has several other settings on the dial including OHMs.

[duaneb55]

Thanks for the clarification on the machine-vs.-manual as it obviously makes a big difference.

So, back to the pilot light and fuse. You need to make sure the fuse is good either by checking for continuity with your Ideal VOM ohm mode or for 115VAC across the pilot light.

The contactor makes a pretty loud clunk when it activates so unless your hearing loss is substantial or complete, I would think you should be able to hear it even if faintly. With the side panels off you would be able to see the contactor plunger retract. Or, using your VOM, check for DC voltage between the work clamp and gun tip and/or wire feed drive housing. Actual voltage will depend on which range setting the machine is set on.

You can refer to the parts break-down to help locate the individual components. Use it to find control relay CR1 and see if it is activating when you pull the gun trigger.

Check these and report back.

[Sheryle]

I think I followed the instructions correctly and here are my findings.

The fuse checked good for continuity.
I pull the trigger and hear a constant low hum no click.
With the cover removed I see no movement of any kind.
Pulled and released several times nothing but the hum when the trigger is pulled and no sound when released.
The voltage between gun tip and work clamp ranges from 200 to 325 mV. Continuity when trigger is pulled not when released.
I found the contactor and CR1 and neither has any movement or sound.

Did I miss anything? Thanks

[duaneb55]

The low voltage reading between gun tip and work clamp with no CR1 or contactor action is a little puzzling so we need to check for 24VAC at CR1 wires #16 and #32 with the gun trigger pulled. If there is proper voltage at 16 & 32 but no CR1 activation, CR1 is bad.

If CR1 activates, check for 115VAC at the contactor small gauge wires #3 & #4 with the gun trigger pulled. If there is proper voltage but no contactor activation, the contactor is bad. If no voltage at 3 & 4, either CR1 contacts are bad or temperature switch TP3 at the output rectifier is bad (open).

Use the parts break-down in the manual to locate the components as needed.

[Sheryle]

I have the owners manual for this machine. I have located the CR1 and Contactor, but unable to find the wires by the numbers you gave. Unless I missed it somewhere, the owners manual does not indicate wire numbers. Maybe what I need to get is a tech or repair manual.

I have loaded pictures in an album in my CP but don't yet know how to get them in this post. One pic is the contactor which has 2 large wires plus 2 sets of smaller wires, Second pic is the CR1 which is the lower relay on the board, I think. I found numbers by the wires in and/or out of the relay, but not a # 16 or # 32. If you could look at the album and guide me to the wires and tell me if I am headed in the correct direction I will check voltages and report back.

Thank you much

[duaneb55]

Unfortunately, your photos are too small and unclear when you zoom in to make anything out.

The wiring diagram in the owners manual shows the circuit wire numbers but some can be hard to make out.

[Sheryle]

Can you tell me from the picture is CR1 the upper or lower relay. My view of the manual looks like it is the lower relay plus it does not show an upper. I checked the 2 not labeled wires on both upper and lower. I got 22 VAC on one wire on the upper relay trigger pulled. The other 3 wires were in the 12 range and dropped to 10 when I pulled the trigger. I'm thinking I need to replace one or both relays. If you agree, where is the best place to by one? Thoughts?? Opinion?? THANKS

[duaneb55]

Sorry I didn't catch it before in your previous post but the upper relay is CR1 which has been replaced as the originals were of an "open" style and the replacement an enclosed style as it is now.

The lower relay is CR2 which is controlled by the trigger of a Spoolmatic 1 spoolgun that would connect to the 4-pin receptacle at the lower right corner of the machine. Jumping pins B and D at the 4-pin spoolgun receptacle should activate CR2 and close the main contactor.

To answer your question regarding replacing the relays, CR2 is only associated with a Spoolmatic 1 spoolgun so focus on the upper relay for now other than a 4-pin receptacle jumper test of CR2 mentioned above.

It's possible a previous owner got things mixed up replacing a failed CR1 so I can't stress enough how important it is to identify the individual circuit wire #s and where they are connected to CR1.

Are you familiar with the drawing symbols for normally open (NO) and normally closed (NC) contacts?

[Sheryle]

T with T upside down on top normally open and same symbol with a diagonal line across normally closed?

[duaneb55]

Correct. And the symbol for the CR1 relay coil is a circle with CR over 1, CR2 is a circle with CR over 2 and the main contactor is a circle with W as shown in the diagram on manual page 28. The small numbers next to the lines representing the circuits are the individual wire numbers you're looking for.

[Sheryle]

[Here is what I have found. If I jump B & D on the spoolgun receptacle I get a click and can see movement, albiet slight in CR2. I used my mechanics stethoscope and hear a click and a hum from CR1 when I pull the mig gun trigger. I don't see any movement but that could be because of the position. There is no other movement on the rest of the machine visible to me. I have pulled the trigger and looked from different angles and stiil see no movement.

On diagram 8-1 in the manual I found wire # 32 that traces back to CR1. Actually before it reaches CR1 the wire becomes # 36. It connects to the CR1 circle with no more information except this ..attached below.

ATTACH]239551[/ATTACH]

I checked VAC at all the terminals of CR1 and here are the results

----(1)7VAC ----(3)7VAC
----(4)7VAC ----(6)7VAC
----(7)7VAC ----(9)7VAC
----(A?)21VAC ----(B?)19VAC
I hope this makes sense and I appreciate all you do.

[duaneb55]

What manual revision are you working with and to what point(s) are you checking between CR1 terminals?

[Sheryle]

The manual is dated March 1991, effective with serial no. KA898403.

The voltages were taken from a ground wire at the bottom of the machine to each terminal. I thought about, but did not take any readings from terminal to terminal. I could if needed.

[weldbay]

Does the wheel turn when take off the pressure. There are two wires coming from your dirve motor usually to the board when you pull the trigger if the conactor closes you should have vloltage to the motor. I do not remember if the JG 1986 models had a DC motor but I susbect they do if you have brushes and are getting votlage to the motor wrap on the brush holders with the plastic end of a scew dirver see it they are stuck and of course check to see it the are good and the Armature is clean,.

If you are not getting voltage to the motor then your speed control board might be bad.

[duaneb55]

Originally Posted by Sheryle

The manual is dated March 1991, effective with serial no. KA898403.

That manual is for a later machine and according to the SN you posted in your first post, the link I posted in post #2 is the correct manual for your unit and may be of more help.

[walker]

You need to have her do the paper clip trick before getting too involved in the manuals.

[duaneb55]

I side stepped that one due to what Sheryle posted in post #1 regarding the guns on the MM250. The reported results of the 4-pin spoolgun receptacle jumper test indicated the main contactor isn't activating so I'm leaning in the direction of a problem in the 115VAC secondary circuits with either one or more components or the power output itself.

[Sheryle]

She is a 62 year old he and this is not the first time that has occured nor will it the last. . Thanks to everyone . BTW the wheel does not turn with or without pressure and I tried pushing to see if it was just stuck.

Duaneb55. When I originally put in my serial # JG088367, I got a 5 page manual for a GA-20C gun. So before when I was searching I just requested a MM200 manual and did not follow the link you gave me because I thought I already had one. My Bad, I now have the correct manual I think. It is 1987 starting with JF926444 model MillerMatic 200 - SKP-35.