100en turbo spluttering

[scotto75]

Hi,

I have a 100en that I picked up in a bit of a state for £20. The earth lead looks like it has melted from having the torch resting on it while hot. The clamp is old and knackered. The wire feed is smooth with no issues and I have changed the swan neck, liner, nozzle and shroud.

I cannot get a consistent weld on 2mm steel, on 2 Max and WFS 6, as per the Clarke manual. Sometimes it sizzles. Other times it splatters. Occasionally it appears to cut out and I can feel the wire pushing the torch away from the workpiece.

I am planning on replacing the earth clamp and cable, but can anyone explain what tests I can do on the earth clamp, torch or power output, to understand exactly what is happening?

Thanks.

 

[mike 109444]

Just remember a mig is a basic DC power supply ! (in the range of 14 to 28 V)
You could flip off the wire feed roller and then attach a meter probe to the welding tip and the other probe of meter clamp in the work ground clamp. Set meter to DC volts! and lock trigger on (with say a rubber band). Note the reading on meter and then flex and twist the ground lead watching meter for dip in voltage due to breakdown / poor connection. This may show it up but note this is not testing it under load (as welding would)To test it under load you would need something that needs 24v at a high current. (couple of car headlight lamps?).
Failing all the above you could just go over the connections inc the connections on the diode pack. Undo, clean and refit.

 

[mike 109444]

Bristol's gunna be glowing over the weekend
You might even see it in Wiltshire....
Don't think he needs to fully load it though.

 

[rikrobson]

I gott one free with a free £28 160A buzz box and it does the same.
It only had two diodes with a centre tapped tranny
It takes a bit of getting used to. Turn it up to two high.

 

[scotto75]

Just managed to grab two minutes in my workshop and cut and stripped the earth cable closer to the machine, removing the dodgy looking bit of cable and the crappy clamp, and used some mole grips to fix the copper cable direct to the workpiece and..... success! Managed to get a good bead with nice penetration using a slightly lower WFS as listed in the manual.

Not much time to do anything else, but a new heavy duty brass clamp and a few metres of 25mm cable so should be happy welding from now on!! Very glad I didn't have to start sticking my test leads onto any diodes.

 

[mike 109444]

Crappy earth return is probably 95%+ of mig problems imo

Think you only need to look at the teeth on the "jump cable" type clamps and the burning/build up to see where a poor connection can occur.

 

[scotto75]

It's been a couple of weeks, but wanted to conclude this by saying I have just fitted a Weldline brass 300A crocodile clamp onto 3M of 25mm Earth cable and the original dinse plug and there's a vast improvement. Pretty much eradicated the previous issue with spluttering.

Now I've just got to deal with the super sensitivity of the wire speed control

 

[mike 109444]

Might be that someone has fitted the wrong type of pot for the wire feed control. Or if the pcb has a 2nd variable resistor on it then you could try a slight adjustment to that.
Is your pcb like the pic ?

 

[scotto75]

Hi Mike,

I don't think so. I think mine looks slightly different.

I've tried on several occasions to learn basic electronics, but I have never ever soldered anything that has worked

 

[mike 109444]

More like the 150 pcb then!

 

[mike 109444]

I know it's not easy going but read the section in link https://en.wikipedia.org/wiki/Potentiometer#Potentiometer_construction
"Resistance–position relationship"

 

[scotto75]

Hehe... I turn 40 tomorrow and here I find myself, tucked up in bed reading about potentiometers! Anyway, that does look more like my PCB, and with my new found understanding I'll take a stab and say that the A on the 10KA means it's a linear pot?

 

[scotto75]

I just measured the feed speed and I'm getting:

Setting Speed - metres/minute
1 0.9
2 1.4
3 2.6
4 4.3
5 5.9
6 7.9
7 10

I didn't bother measuring past 7 as 10m/m seems like quite a lot. At the moment I'm usually around the 2-4 settings.

 

[rikrobson]

I may be wrong, but isnt the wirefeed voltage on these taked from the secondary side of the main transformer? If so the voltage will change depending in the chosen settings. this will affect the wirespeed depending on the welder setting.
If not it will have its own transformer and the speed will be setting independent.

 

[scotto75]

Ah, so these results could only be applicable for the 2 MAX setting? I'll put it on the other settings and do the same and see what changes.

 

[rikrobson]

I just checked the wiring diagram and it is supplied by the welding feed, so the speed will change with the welding settings

 

[mike 109444]

Best you can hope to do is a comparison and if you make any adjustments to say add an additional pot as a fine control, where the original could be called the course. You could attach a volt meter (set to DC volts) on the connections of the wire feed motor (use clips) then make up a table as you previously have done then add in the fine control and look for values between the values you had in you table
Say
1 = 8v
2 = 10v
3 = 12v
4 = 14v and so on
then with fine see if you get
1 course, 5 fine = 8.4
2 course, 5 fine = 10.4
and so on.....

 

[scotto75]

On a welder with this type of feed power supply there is, imo, no reliable way of measuring the actual wire feed speed.

Hehe.. the words "no" and "reliable" together seems to sum up my general opinion of the wire feed control on this machine. Even though the manual has stated that setting 6 is the starting point for 2mm with 0.8mm wire on 2 MAX. I can't get anywhere near 4. I'm just a touch over 3, but go one way over or under just by a smidge and it goes pear shaped.

 

[scotto75]

add an additional pot as a fine control, where the original could be called the course.

I like this a lot. Not sure if I could pull it off though, but it's stored in the memory bank for a rainy day!

 

[mike 109444]

Hehe.. the words "no" and "reliable" together seems to sum up my general opinion of the wire feed control on this machine. Even though the manual has stated that setting 6 is the starting point for 2mm with 0.8mm wire on 2 MAX. I can't get anywhere near 4. I'm just a touch over 3, but go one way over or under just by a smidge and it goes pear shaped.

You could try replacing the pot for a new one (< £5) of same value and type. As original may be worn in that part of the track. As a temp repair (with power off!!) try some switch cleaner or as a desperate measure WD40 squirted into the pot, then work it back and forth.