Migatronic Rally 166 issues

[racky]

Hi all,

This is my first time on here looked like the best place to go with my question. Im new to mig welding and am hoping to learn by doing in order to complete some projects i have in mind. I have been given a migatronic rally 166 which I was hoping to use for the job.

Annoyingly when I turn it on and pull the trigger (euro torch) it all appears fine the wire feed motor kicks in etc but after a few seconds it clicks and buzzes before cutting out.

I have recently changed the capacitors not sure if this would be an issue tho?

Any suggestions would be great!

 

[mike 109444]

Welcome racky. When you say wire feeds ect then clicks ect are you just feeding the wire or trying to weld? If you are just feeding wire and not making the circuit to weld then there is probley a fault with the feed motor, it's wiring or the board driving it. If it's when trying to weld then it could be a fault with the transformer, diode pack, "smoothing capicacitor/s". If the latter then maybe recheck your connections to the capicator/s. They will need to be connected the right way round (like a battery) they will have a "+" and "-" connections. Pics of inside of m/c will help in pointing you in right direction

 

[racky]

Hey thanks. I will take a look tomorrow, was hoping it might be a dodgy connection to the motor. At the mo I was just trying to feed wire havnt attempting welding with it yet. If its a problem with the board do you know if thats fixable or would it be a relplacement? and is that expensive/worth the effort?

Will take pics and try posting tomorrow, thanks for the response!

 

[racky]

Hi Mike,
Had a look at it today. tested the connections to the wire feed motor, one was ok but the other had nothing, traced it back to the circuit board, doesnt appear to be damaged in anyway but guessing the board must have a fault I cant see. here are some pics (ignore the blue wire at the bottom it shouldnt have been in the pic) am I right in assuming its the board, what u reckon are chances of a new one?

 

[mike 109444]

It's possible there is a fault on the board as that controls the speed to the feed motor. But it could also be the motor or it's gearbox (tight maybe) Try backing the wire feed pinch roller right off so it can't feed any wire. That way it will be under minimal load then operate trigger. If it runs ok and can be adjusted up and down on the speed then listen to the motor to see if it sounds rough. Could be just a strip, regrease and refit might cure. If it is still failing with no load then you could try running the motor from a battery charger/12 v power supply (after unpluging from welder wiring!! The motor should run at a fair speed with 12v applied (it will prob be a 24v motor) If it runs ok then you may well be looking at a board fault. Could be after running motor for a while from batt charger under noload it might just cure it if it's just a sticky motor. What caps have you replaced? can's see them in pic, or are they ones on the pcb?

 

[NotANormalCoder]

Most of these small Migatronics require some feedback from the welding current supply before they start the motor running. If there is no output from the welding transformer, they do exactly as the OP described. Click, buzz, clunk! and no motor action. This can be caused by a wiring fault ( check the main contactor) or most often, poor soldered joints on the PCB especially on the two heavy duty resistors - bottom right of your pic, with green/blue colored tops. Check these and if you are handy with a meter, see if there is any welding voltage output from the machine when you pull the trigger. Also, check soldering on the pcb where the multipin plug is.
Dave

 

[Robotstar5]

Most of these small Migatronics require some feedback from the welding current supply before they start the motor running. If there is no output from the welding transformer, they do exactly as the OP described. Click, buzz, clunk! and no motor action

That's interesting, the weldsets at work are slightly different, if they don't detect an arc established signal after a couple of seconds, contactor drops out & gas shuts off but wire feeder keeps running, I assume it's so you can feed a new roll of wire without wasting gas?

 

[NotANormalCoder]

Depends on the design of the machine. Bigger, industrial Migatronics had a slow start system that reacts to the arc established signal - wire feeds slowly until arc lights up, then the motor speed increases to whatever speed is set. If I remember, smaller sets use the supply from the welding rectifier to power the motor - no weld supply, then no motor. Modern complex/synergic/pulse MIGs need the arc started signal to allow the electronics to adjust to the correct weld parameters. A pain if you only want to feed the wire through the torch but most have a button lurking somewhere which feeds the wire at a faster speed.

 

[Robotstar5]

Depends on the design of the machine. Bigger, industrial Migatronics had a slow start system that reacts to the arc established signal - wire feeds slowly until arc lights up, then the motor speed increases to whatever speed is set.

Yes, these weldsets have a similar function, called "creepstart" I've been asked to change sets by our production welders due to a (percieved) fault - turned out the previous shift welder had left the creepstart switched on!

 

[racky]

thanks for all the advice guys really appreciate it. Have spent the morning stripping it out trying to see what the problem is. I hooked the motor up to a 12v supply and it ran fine, had it run for a few minutes.
I took the capacitors out and the PCB board. The board appears fine the sodlering looks good, have given it a clean but I cant see anything obvious.....this is starting to frustrate me was hoping it would be somethig obvious and simple but then nothing ever is.
I have added some more pics, below, am thinking it must be a problem with the board that I just cant see.......

 

[NotANormalCoder]

With the pcb refitted and machine turned on, you need to measure for DC output from the machine. You should connect your meter to the tip of the torch (+ve) and the earth clamp (-ve). When you pull the trigger, you should see something around 20/30V. If you don't see this (and it will be a fairly short time that it appears for) then there is something wrong in the supply to the main transformer. You need to check the contactor (in front of the ali plate, with many wires). With mains OFF, check continuity across the contacts between live and whatevers opposite it and neutral and whatevers opposite it. Do this by pressing the centre of the contactor from the top, with a small screwdriver. You should see a short (3/4 Ohms) if the contact is good. If you don't get a short, the contactor is shot and needs replacing.
Difficult to understand if you're not familiar with these parts, but best I can do in writing.