Millermatic 135 Amperage Problems

[Dirtbmw20]

Hello all, newbie to the forum here.

I have a Millermatic 135 that I am having problems with the amperage adjustment on it. It doesn't matter how much I turn the amps up on the machine, it won't stick a weld for nothing. It does nothing but spit and spatter when the trigger is pulled and while striking an arc, you can turn the amp adjustment knob and NOTHING happens, no change at all. I can take a piece of 24 gauge expanded metal and cut the machine all the way up to 10, when it should burn right through thin expanded metal like that, it won't even stick the weld to it. I have had the machine for a little over 4 years and this just started about 2-3 weeks ago, it's just taken me this long to figure out what the problem is. My question is this...............................

How do I figure out WHAT is bad on the machine. I called my local Miller distributor today and he said it could be anything from the rectifier to the pc board to the potentiometer switch but how do I figure out WHICH one is bad. I priced the potentiometer switch today at about $19.00 bucks so if it's that then it won't be too bad but if it's a pc board then I could probally buy a new welder for what it will cost to fix this one. Any suggestions would be greatly appreciated.

[Steve]

Do you know how to use a multimeter? If so I can tell you where to look but need model and serial number of your machine. If not then take it in and have it checked. If its a board (my bet) then you can get repair costs and go from there. I looked at the generic 135 diagram in manual. Pretty simple. The board does it all for controlling output. The transformer ups whatever it is given and the rectifiers do their thing. Might check the ground clamp, but you probably already done that.

[Dirtbmw20]

Do you know how to use a multimeter? If so I can tell you where to look but need model and serial number of your machine. If not then take it in and have it checked. If its a board (my bet) then you can get repair costs and go from there. I looked at the generic 135 diagram in manual. Pretty simple. The board does it all for controlling output. The transformer ups whatever it is given and the rectifiers do their thing. Might check the ground clamp, but you probably already done that.

Steve, Thanks so much for the reply back. Unfortunately, NO, I don't know how to use a multimeter BUT my best friend is an electrical engineer who does know how. The model is a Millermatic 135 and the serial# is LC516277. There is a parts breakdown and a schematic of the pc board on the Miller site, I've got that all printed out. My buddy is betting on the potentiometer being bad but the welding shop said it could be that, the rectifier, or the pc board. I have checked the ground and it is clamped tight to the work piece, the nut holding it inside the machine is tight and there are no cuts in the cable, anything else it could be with the ground ??? Is there a way to check the rectifier or the pc board with a multimeter ??? I did get a price on the potentiometer today for about $19.00 bucks but failed to ask about the pc board. Do you have any idea or clue as to what a pc board might cost for this unit ?? Thanks again for the reply back and any help is greatly appreciated.

[Steve]

Getting the manual as we speak. When I get it downloaded I'll take a look and follow with hopefully something good. As your best bud is an electrical engineer then I will refrain from telling yall to not touch the hot stuuf. How can you tell if its hot? ya can't so keep your hands on the leads or one in your pocket. Anyway not done downloading so my background is 21 years aviation electronics on F-106 and F-15 aircraft and test stations. FYI

[Steve]

OK here we go Dirtbmw20. First things first, Check the remedy box items on page 28 for No weld output, wire feeds and the next one following Low weld output. Thats it for Miller recommendations so if all that stuff is ok then onward we trundle. Where to start, the beginning. Only difference in the 115 and 230 models is the power input and the power switch,transformers and such,and how they connect to the board so If 230v check rc10 to rc5 for 230 or so volts. If 115 then check rc4 to rc5 for 115 volts or so. Turn the unit on and check the fan voltage rc2 and rc3 , If thats 24 volts or so then the power should be ok. But then if the wire feeder works ok then I would think the power is ok. Break time.

[Steve]

Back from break. If you want to check the voltage control adjustment R1 then you may want to use an analog meter so you can see the voltage swing. At any rate check the voltage across R1 at 3 and one. We are interested to see if the voltage changes so tie into 3 and 2, turn the voltage control from one limit to the other, min to max, to see if it does. do the same to 2 and 3. If the voltage changes then R1 should be ok. I don't know what the voltages should be. Then tie into T1 1 and 2 and turn the voltage control min to max. The voltage should change accordingly. If it doesn't you need a board. If it does then on to the SR1 rectifier. You might have to disconnect the X3,X2, and X1 leads from the transformer and disconnect one of the capacitor leads on both diodes. There should be a few ohms of resistance one way and a lot of ohms the other way. Put the red lead on the arrow side, black lead on the other , note reading and reverse the leads. If you get about the same reading both ways then the rectifier is toast. You may want to check for loose wires along the way. T1 is probably ok if it doesn't smell like burnt insulation or look toasted. Thats all I got for now. Happy hunting!

[Steve]

Don't forget to turn the machine off and discharge the capcitors before removing wires.

[MAC702]

Where is this $19 pot? If it's from a dealer, you can save a ton of money by getting the equivilent from Radio Shack.

My PowCon 300SM needed a new control pot. $40 from the PowCon place, or $4 from Radio Shack. The Radio Shack version has been welding happily ever since.

[Dirtbmw20]

Steve, Yea, no need to tell me to not touch the hot stuff, I know enough about electrical stuff to know I shouldn't even open the cabinet on this thing, I'm clueless,lol. I'm sure my buddy knows better, he's a pretty smart guy. I'm gonna be taking it to him tonight so he can check that potentiometer switch, he said he wasn't sure if he could check the rectifier or pc board until he saw the machine or at least the diagram, which I have both. The info you've thrown at me is foreign to me but I'm sure it will be extremely useful to my buddy when he starts checking this thing. He works 2nd shift at Helmac (the lint rollers that you see in the stores) so I have to go by his work tonight when I get off work, first thing we'll do is log onto here tonight so he can read all what you suggested. I REALLY do appreciate all the suggestions, hopefully it will help him figure this thing out. I'll keep ya updated and let you know what we find out. I may be hollaring for you again tonight when we get into it,lol.


MAC702, Yes, that $19.00 pot was from my local Miller distributor. I had one quoye me $22.00 and one quote me $19.00. I may check my Radio Shack if that is the problem, thanks for that suggestion.

[Steve]

Aloha! Cold here so thought I'd use a warm greeting. The items I referenced are taken right off the diagram. If anything is confusing let me know.

[Dirtbmw20]

Steve, We tested everything we could tonight, he followed your directions to test everything. When we checked the voltage to R1 at 3 & 1, we got nothing. We tested R1 at 2 & 3 and got nothing there either. I can't find any T1 on the pc board diagram, I'm not sure if my buddy saw a T1 or not but I don't see a T1 on the board at all. He said from the test you gave us to try and what you are describing, he said he thinks it is the pc board. This really ticks me off. I think a pc board is just gonna cost too much to fix the machine, I haven't priced one yet but I would rather take my "repair money" and put towards a new machine if it's gonna be alot. I'll call my local Miller distributor tomorrow and get a definite price on a board, until tomorrow, you got any clue as to what a board costs ???

On a different note, when we had the cover off I noticed a red and a green light on the pc board, the green light comes on but the red light never came on, I don't know if that has any significance to my problem, just thought I would throw that out there. Does all this sound like a pc board problem to you as well ???? Steve, I really do greatly appreciate all the help, suggestions, and time you've spent helping me.

One other question. Looking at new welders and I want to get AWAY from a 110V unit and go to a 220V unit. What are your personal opinions on the Miller180, the Hobart 187, and the Hobart 210 ???

[84ZMike]

Have you checked on the warranty?...you said you have had it a little over 4 yrs so you could get lucky and still have some left.
Mike

[Steve]

The T1 referred to is a transformer located at bottom rear right corner of the machine. However if R1 doesn't have anything at 3 and 1 from the circuit board, then R1 can't tell the board what voltage you want. As for the lights on the board I have no clue unless green is for go and red be for stop there is a problem. So one last thing to try. Ohms check TP1 at 1 and 2 with the plug disconnected. I think that is an over temp sensor. It should read zero ohms. Normally it would be closed unless T1 overheats, then it would open, welding current would be nil, and the PL1 thermal overload lamp would come on if the bulb is not burned out. If that checks out then I'm afraid it looks like the board is bad. . Not having a diagram of for the board itself I can't go any further. I tried to get a cost for a board but Miller refers to welding suppliers. So you would have to find out from them I reckon. Follow up on the warranty thing for sure like 84 says. Never know it might pan out. As for new welders, 220 units would give you more zip, might require some wiring to get the required power available to the unit. Not having used any of the welders you mentioned, I have no preference amongst them. All our welders are Big 40's or 460 three phase. We have even double banked a couple of big 40's a time or two in the field. So me personally would not purchase any of the three for work. Consider what you want to do with a welder amperage wise and let your pocket book decide. You're welcome too I'm sure.

[Dirtbmw20]

OK, I rememebr him checking the transformer last night and it was good. Everything is pointing towards the pc board. A WHOPPING $288.00 bucks from my distributor for the board and they want $65.00 to install it. I can install it but I ain't sinking $288.00 bucks into a REPAIR on this machine, I'll take that hard earned money and put towards a new welder.

84ZMike, as far as the warranty is concerned, my distributor ran my serial number and said the warranty ran out about 1 year ago BUT I am calling Miller and let them know how unhappy I am with my 4 year old machine. I haven't even gone through one roll of small wire with this machine nad not even close to one bottle of gas, that's how little use this machine has, this should not be happening to a machine this new or with this little use on it.

[Dirtbmw20]

WOW !!! I just got off the phone with Miller and they said they would send a pc board to my distributor for FREE, I would only have to pay my distributor's labor charges for installing the board, even though the machine was over 1 year out of warranty. That's pretty good customer service right there.