ESAB (Snap-on) Smashweld 180 Stuttering

[Graham Francis]

Hi All

I'm taking a look at a mate's welder that was returned to him after lending it out. It needed a new torch and wire and given it was in a bit of a sorry state, initially he though the wire feed motor had packed up, but we think that's because he'd forgotten to put the front toggle switch on the 'bead welding' setting

Putting it to the test, we then found it to be what I can best describe as 'stuttering' when running a bead weld across some 2mm steel. It was sounding like the arc transformer was tripping in and out. Given 50% of the strands on the earth clamp cable were missing, I then cut and re-clamped and soldered the cable, so that's now good. This seems to have improved things, but I'm not convinced its working as well as it should. It's certainly not as smooth as my Eland 160 @eddie49 .

The other thing we've noticed is that the first three settings on the weld current (voltage?) switch don't provide any output (i.e. no wire feed). I think it's been like this for sometime and is not a huge issue given he's mostly been using it for chassis rather than bodywork repairs.

Before looking any deeper, I thought I'd get your thoughts here. I'm also wondering whether the 'stuttering' is possibly the the Contactor tripping in and out under load. Finally, does anyone have a circuit diagram for this machine? I've downloaded the manual for it from the ESAB website.

Cheers and stay safe everyone!

Graham

 

[a111r]

Have you measured the open welding voltages across the range?
If the motor's not feeding on the lower three and the upper are lower than spec, I'd work backwards from the rectifier's diodes.

 

[zzr1200]

My old ESAB compact mig had the wiring diagram on the inside of one of the screwed on covers, might be worth checking...

 

[Bobbes]

I think this is the manual you looking for.

 

[angellonewolf]

is it rocker switches if so they might need a clean

 

[eddie49]

Thank you for the manual and circuit diagram, Bobbes. It shows that this ESAB has the same centre-tapped inductor and two extra diodes as this Snap-on/Blue-Point/Cebora:
https://www.mig-welding.co.uk/forum/threads/snap-on-mb135-with-slow-wire-feed.107229/#post-1716544
I do not know what that diode arrangement is for, or how it works. Voltage feedback maybe ?
The diagram also shows that the main transformer has two paralleled windings on the primary and on the secondary.
Regarding the "no wire feed" on first three power settings" - as well as no wire, is there also no gas valve and no arc at those three positions?
The machine has an independent auxiliary power source for wire feed and controls, so wire functionality should be independent of arc voltage.
However, the 7-position power range switch also contains as a double-pole On/Off switch ( Off in position 0 ), so maybe a mechanical fault in the switch causes that main switch to be Off in the first three positions....

 

[Graham Francis]

Firstly, Happy New Year to you all :-).

I've just re-checked what I'm getting on each of the power switch settings. It's actually slightly different to what I first thought. Am not sure why - maybe my error or maybe some fiddling and poking I've been doing has changed something ;-).

In any case, this is what I'm getting:

On position 2 and position 7, the gas valve is operating (it operates on all settings) but there's no wire feed and no arc from the torch. On all other settings, the wire feed, gas valve and arc are operating. I'm also able to vary the wire speed on all of these settings. However, it seems I'm getting maximum arc current on position 1 which surprises me. I was expecting this to be the lowest setting.

I'm assuming the three position front toggle switch (SW1) allows for selection of stitch, spot and seam welding options. On this machine, only the seam welding (toggle to the right) produces any output. With the switch in the centre or the left, nothing happens when pressing the torch trigger.

One other thing I've noticed is there is either no cooling fan, or the fan (or its control circuitry) has failed. Also, there is no separate 'on/off' switch on this machine, which I find odd, so I'm guessing position 0 of the rotary power switch means the welder is switched off and for every other setting it's switched on.

I'm also guessing that know on the front lower left of the front panel is the spot and stitch timer - again, turning this has no effect with the toggle switch positioned to the left or centre.

Given the wire feed motor, gas valve and wire speed adjuster seem to be operating correctly, I'm assuming transformer K9 (Aux Transformer?) is working correctly. I'm also seeing 200V out of the tap with the rotary power switch in positions other than zero, but it's not clear to me what this 200V tap is used for. Looking at the wiring diagram the primary side of the arc transformer (K1) has parallel windings on both the primary and secondary as you say Eddie.

I also put my meter across the 200V terminals on the connector block and without pressing the torch trigger I'm getting 0V and with the trigger pressed I'm getting 215V. Not sure if this is correct or not.

That's about as far as I've got at the moment!

Graham

 

[Shedendman]

All these faults after lending it out,i'd be bloody fuming

 

[northwest]

All these faults after lending it out,i'd be bloody fuming

Oh, I loan mine out all the time, with me attached to it!

I learned long ago and fortunately people around me know, don't ask.

 

[Graham Francis]

Oh, I loan mine out all the time, with me attached to it!

I learned long ago and fortunately people around me know, don't ask.

Totally agree with you guys, however, I think the 'power switch' issues might have been there for a while before. Want to see if I can get it properly sorted for my mate if I can. Maybe then we can have a welding party :-0

 

[Graham Francis]

Have just checked the 230 (240V) output from the front panel rotary switch and I'm getting 240V on settings 1 through to 7 - that's the red wire coming back from the switch on terminal 7 of the connector block counting from the left. 'Mains in' is across terminals 1 (L) and 4 (N) from left to right. I get 0V on terminal 7 on setting 0 on the rotary power switch, so I'm guessing that's effectively the on/off function. I can't see a fan inside this machine, so perhaps these were never fitted with one. Time for me to also read the manual I think ;-).

Cheers

Graham

 

[Graham Francis]

Some more testing...

Having read the manual, i followed the instructions for spot and stitch welding (rotary switch on position 7 and wire speed full on). With toggle switch positioned to the left (stitch) the gas valve operates, but nothing else. With the switch in the center (spot), I get nothing (i.e. no gas valve or wire feed).

Has anyone got a PCB diagram for this machine? I'm guessing there is an on-board timer function similar to my Eland - possibly a 556 timer?

 

[Graham Francis]

Just learnt that this welder is also known as an Arcos Lincoln 180c. Not sure whether this will widen the search across the 'knowledge pool' on here.

 

[eddie49]

Yes, that information about alternate branding for this machine helps a lot! There are some useful earlier threads on this Forum for the Arcos and Lincoln Minimig versions:
https://www.mig-welding.co.uk/forum/threads/arco-lincoln-minimig-180c.29900/
https://www.mig-welding.co.uk/forum/threads/wire-feed-roller-for-lincoln-minimig-180c.96612/ -- has a clear circuit diagram in post #5
https://www.mig-welding.co.uk/forum/threads/snap-on-minimig-180c-wont-start-got-nothing.15762/
Regarding the non-working positions on the main power switch: from the diagram, after the double-pole on/off switch ( Off in pos. 0 ) has been enabled, the rest of the switch looks like it functions as a simple 1-pole 7-way selector switch.
If you put an Ohmmeter set to the 200 Ohms range across the ( pair of ) transformer primary winding(s) from "0" to each of the 7 tappings ( numbered from 2 to 8 ) in turn, there should be continuity with a resistance of between 1 and 2 Ohms. The meter will probably not be sensitive enough to show increasing resistance on each tapping, but there must not be any that are open-circuit.
If the transformer checks out OK at each tapping, test again but measuring from "0" on the transformer to connection "15" on the rotary switch and turning the switch though each of the 7 power range positions. If any position shows open-circuit, that would indicate that the switch is faulty.

 

[Graham Francis]

Many thanks for this @eddie49 I'll do so more testing later and report back.

 

[Graham Francis]

Hi all.

Finally got round to doing some more testing - been a bit cold and damp outside recently .

Firstly, I've re-insulated the connections to the primary windings of the arc transformer as the original sheathing had shrunk back (see photos). It looked like there might have been some that were shorting, but now these are all good. I also doused the inside of the switch with contact cleaner. I was half-hoping that insulating these connections would fix the 'problem', but not so. What seems to be happening (with the exception of the rotary switch being in positions 0, 2 and 7) is I'm getting maximum weld current (voltage?) which I can only regulate by adjusting the wire speed control. As an example, on the lowest setting (1) with wire speed set to around 2, the wire is burning back up the torch. If I then turn the wire speed up, I get the same amount of power as I do on position 6 of the switch with the same wire speed, so something's obviously not right.

Back to @eddie49 's suggested tests and readings, this is what i get:

Between '0' on the primary (both sides) and the following switch terminals on K4, this is what I'm getting (assume approx. values due to meter sensitivity):

Terminal 2 = 1.1 Ohms
Terminal 4 = 1.0 Ohms
Terminal 6 = 0.9 Ohms
Terminal 8 = 0.8 Ohms
Terminal 10 = 0.7 Ohms
Terminal 12 = 0.6 Ohms
Terminal 14 = 0.5 Ohms

This would suggest the primary windings of the arc transformer are OK.

In terms of the rotary switch, checking continuity between '0' on the primary and terminal 15, I'm seeing an open circuit in positions 2 and 7. This accounts for why I'm not getting any wire feed on positions 2 and 7 and points to the rotary switch being faulty. However, I'm not convinced this is the cause of the welder operating on full power on all settings, unless it's failing in a way that's somehow creating this effect.

Before I source a new rotary switch, it would be good to get some thoughts on what else (if anything) may be causing it to operate on full power on all settings.

Cheers

Graham]

 

[Graham Francis]

OK. So some more testing this morning! As well as continuity between terminal 16 and terminal 2 on the rotary switch in position 1, I'm seeing a short between terminal 16 and 14 with the feed to the primary side of the arc transformer disconnected from terminal 14 (just to make sure I wasn't getting a short through the primary windings). This explains why I'm getting max power on position 1, when it should be the lowest setting as terminal 14 connects to the lowest resistance (hence highest current) winding on the primary side of the arc. There are some other internal shorts on other settings of the rotary switch that a creating a path to the lower resistance windings on the lower settings, so I've done enough testing to convince myself it's the rotary switch that's failed.

I'll see if I can source a replacement and go from there.

Cheers

Graham

 

[eddie49]

That sounds like a good explanation for the maximum power in Pos. 1 situation. A switch contact may have detached from it's cam, or the cam has lost indexing by the shaft.
Hopefully there will be a maker's name and a type number on the switch. From the manual that Bobbes supplied, the switch part number is 320 988-01, but I cannot find any examples of that.
There are some MIG selector switches here:
http://www.spaw-serwiscz.pl/index.php?cPath=284&spaw=e9bfce29d2a6621084584c6ca290b0d8

 

[Graham Francis]

After googling around and getting in contact with the above supplier, I wasn't able to find a replacement rotary cam switch. However, I did find something I could use on Amazon in addition to fitting a separate double pole on/off switch. The rotary switch only has 6 positions and not 7, so I would have to lose one of the step-up windings, so I chose to leave feed '6' to to the arc transformer disconnected and isolated. This would mean I would get the step up in current from positions 1 through to 5 and then have a double step from 5 to 7.

I've since fitted and wired in the new rotary and double pole switches and it now all works fine. I needed to strap across the 'input terminals' on the new rotary switch as it's not quite as 'smart' as the original and take a feed to it from the switched side of the double pole switch. The terminal clamp and screw sizes on the rotary switch were exactly the same as the originals, so it was an easy fit. The only thing I needed to do was to a cut a larger bore hole in the face panel, plus drill a new hole for the on/off switch.

For approx. £20 and half a day's work, I've now got a pretty good workaround. It's not perfect as I now only have 6 power selections and not 7, but it's certainly good enough and now means it operates on the lower power settings which it wasn't doing before.

This approach might help others perhaps stuck with a similar problem as I had and happy to spend a bit of time re-wiring and re-fitting a couple of switches. Here's the links to the items I bought:

Changeover Switch 20A 500V 4W HZ5B-20/3.0-6 12 Terminals Rotary Changeover Switch 7 Position Rotate Cam Combination Changeover Switch: Amazon.co.uk: DIY & Tools

Shop Changeover Switch 20A 500V 4W HZ5B-20/3.0-6 12 Terminals Rotary Changeover Switch 7 Position Rotate Cam Combination Changeover Switch. Free delivery on eligible orders of £20 or more.

www.amazon.co.uk

On-On Standard Toggle Switch DPDT 15A 250VAC | eBay

On-On Standard Toggle Switch DPDT 15A 250VAC.

www.ebay.co.uk

The rotary switch comes without a diagram, so you have to work out which contacts connect on which positions, but that's easy to do with a meter. The only other thing that's a bit of a pain is that the switch has to be slotted through the front panel and then wired up. My photos of the wiring show the switches wired up for testing before I drilled the front panel ;-)

I've also attached some photos below.

Cheers

Graham

 

[Manc]

Hi thanks very much for sharing.
Will try and repair my Minimig 180c