SIP Wire Feed Motors

[Richard Pearson]

Hi,

New poster here.

I have a couple of SIP mig welders that I have had for several years and by and large are happy with them.

My Topmig 170 Turbo has just eaten its wire feed motor - the commutator has fallen apart - and I was wondering if anyone knew where I might find a replacement. They are 24v motors.
If that is impossible can anyone recommend a replacement wire feed assembly that would be relatively easy to fit?

Many thanks.

 

[zzr1200]

Try searching "24 volt mig wire feed motor" on Fleabay loads come and not expensive at all..

Or search for Euro mig torch conversion and wire feed motor.

 

[a111r]

Post up a photo of the motor. I break up a few MIGs.

 

[Richard Pearson]

Thanks for replies.

Motor dimensions are as follows:
Diameter 28mm
Length 47-48mm
Spindle diameter 2.2mm approx
Mounting holes 16mm centers

The motor is stamped ‘Johnson’

 

[a111r]

Looks like it's the toy-sized motor fitted to most hobby kit. I sold the last one I had for £4.
If your other SIP is not a donor, look for a cheap local one?

Or as said, a euro conversion included, it's not a great feeder anyway:
https://www.ebay.co.uk/itm/Welding-...648815&hash=item594a883cd3:g:iqcAAOSw2FdelREg

 

[Reman]

Don't most of the SIP MIGs have a mechanical gas valve in the gun? If his has, and he converts to a euro torch he'd also need to fit a solenoid valve into the welder.

 

[a111r]

Don't most of the SIP MIGs have a mechanical gas valve in the gun? If his has, and he converts to a euro torch he'd also need to fit a solenoid valve into the welder.

Yes, they do. Not so hard a job, £20.

When we are more able to travel, I'll probably be breaking up one of the old 1980s red/silver 'Original Migmates', rumoured to have a better wire feed.
Like this: https://www.ebay.co.uk/itm/SIP-MIG-MATE/124120352681?hash=item1ce62647a9:g:ofYAAOSwvfxeXUMg

 

[Reman]

Yes, they do. Not so hard a job, £20.

When we are more able to travel, I'll probably be breaking up one of the old 1980s red/silver 'Original Migmates', rumoured to have a better wire feed.
Like this: https://www.ebay.co.uk/itm/SIP-MIG-MATE/124120352681?hash=item1ce62647a9:g:ofYAAOSwvfxeXUMg

Bloody hell ! That's the same controls and chassis as my Migmate 100, but mine's the later black and grey colour scheme. If it's the same internally I can unfortunately deny it's wire feed being any better than later ones. Mines biggest flaw is the inconsistency of its feed speed. When the doctor eventually takes me off these fuzzy head painkillers I'm on at the minute I'm intending to do the wire feed mods to mine because it was always a pig at setup.

 

[eddie49]

That's the same controls and chassis as my Migmate 100. Mine's biggest flaw is the inconsistency of its feed speed. I'm intending to do the wire feed mods to mine because it was always a pig at setup.

The speed variations may be due to the fact that many low-end machines take the voltage for the wirefeed motor from the main welding power, which varies when the arc is truck. The problem, and possible solution, is described here:
https://www.mig-welding.co.uk/forum/threads/wire-speed.99971/#post-1539945

 

[winchman]

I have a complete spare / repairs SIP set for sale in the sales section

 

[a111r]

Bloody hell ! That's the same controls and chassis as my Migmate 100, but mine's the later black and grey colour scheme. If it's the same internally I can unfortunately deny it's wire feed being any better than later ones. Mines biggest flaw is the inconsistency of its feed speed. When the doctor eventually takes me off these fuzzy head painkillers I'm on at the minute I'm intending to do the wire feed mods to mine because it was always a pig at setup.

Yes, externally the same layout but you can see the feed drive is different. Hopefully no flex and the motor beneath is larger - we'll see...

It's interesting that one hardly ever sees a post about Clarkes with this poor wire feed issue.
The motors are same size and are still driven by the welding voltage. The drive mechanism may flex less, but it's hardly a 'step change' in quality...

I'm keen to get this old SIP back because it was mine until 5 years ago. I sold it to a mate who it appears has kept it outside, so it likely looks the same state as that ebay example!

 

[Richard Pearson]

I ordered one of the wire feed motors that are on Ebay and fitted it this afternoon to my SIP 170 Turbo but now I have another problem.

The wire speed controller doesn't seem to work. No amount of twiddling increases the speed. However if I turn up the power setting the speed increases

It's as though the power selector is operating as a speed controller.

What is going on?? have I inadvertently got my wires crossed somewhere?

Any help much appreciated.

 

[Richard Pearson]

Just realised that the same happens on my other SIP 140 Turbo i.e. the speed does increase as you increase the power. This of course makes sense and I am probably just being thick!

So it appears that my speed controller is faulty. Is there any way of checking this? If it is faulty what is the best way of sorting it out?

Many thanks for your help and apologies if I appear a little dense!

 

[a111r]

Yes, the motor runs off the welding voltage, so its speed increases with the 'power' (voltage) setting.
One of the experts will advise about checking components.

 

[eddie49]

As I mentioned in my post #9 above, it is true that power for the wirefeed motor comes from the main welding power. This means that as the welding power selection is stepped up, the motor will speed up. Some people think that this "semi-synergic" feature is a good idea, and some manufacturers ( e.g. Migatronic ) use the welding power setting to bias the motor speed, even though it has its own supply.
The downside, as mentioned, is that the voltage varies during welding and so the wirespeed can be erratic. Solutions are linked to above.

However, you are now saying that after replacing the motor on the SIP 170, the speed controller has no effect at all? At every setting of the main weld power, the speed control knob should allow a range of speed. Moving to the next power setting will cause the motor speed to step up, but it should still be adjustable.
What is the current draw or wattage marked on the new motor? Is the control PCB in your SIP 140 the same as the possibly faulty one in the 170 ?
It may be possible for us on the Forum to help you troubleshoot and fix the 170 PCB at component level. Replacement PCBs are available, or a mail-in repair & return service may be used. However, after fixing the PCB you'll still get the wire speed variations, so you may want to consider going down the modification route as in post #9, rather than repair.

 

[Richard Pearson]

Thanks for the reply.
I think the dedicated power supply mod makes sense - does this do away with the PCB/controller?

Correct that the speed controller has no effect on the wire speed irrespective of the power setting.

According to the blurb on the motor it is 24v and 10w.

I had a look at the PCB in my 140 and whilst similar it is not the same so I didn't try switching them over to see what happened. (The SIP 140 is I think 2003 and the 170 is 1997). The SIP 140 PCB is the same as the one on Ebay for someone who repairs them whereas the PCB in my 170 is as follows:

It says MIG03A IPF on the back.
It doesn't look burnt or damaged in any way - is there anything I can do to test it?

Many thanks for your help.

 

[eddie49]

Thanks for that excellent clear and sharp photo of the PCB from your SIP 170.

It is the "remote relay" version of the PCB. The square black transformer, the circular black bridge rectifier, and the two pins for push-on tags drive the off-board relay ( which controls power to the main welding transformer ).

The upper part of the board is the speed controller. As you can see, there's almost nothing to it. One TO-220 style power transistor ( a TIP35C ) on an aluminium heatsink. One 1K variable resistor and one 100 Ohm trimpot. One diode, two resistors. Probably less than a fiver's worth of components.

Do you have a soldering iron and a digital voltmeter ( DVM ) ? You would need to unsolder and lift one leg of each component from the board and check it on the Ohms or Diode Test range of the DVM. For the power transistor, it would mean drilling out the Pop rivet and unsoldering all three leads to test it. ( That transistor is probably the No. 1 suspect anyway.)

More detail about the circuit:
https://www.mig-welding.co.uk/forum/threads/sip-autoplus-180.70366/

If it proves to be the culprit, here's a replacement transistor:
https://www.ebay.co.uk/itm/TIP-Seri...-Transistor-TIP31-TIP2955-TO-220/312886617301
https://www.ebay.co.uk/itm/TIP35C-TRANSISTOR-TO-247/202015618320

 

[Richard Pearson]

Many thanks for the very helpful reply.

I ran a few simple tests on the PCB and discovered the following:

Power is getting to the little transformer
The low side was reading 19-20 vac so the transformer is good.

I then checked the little rectifier across the positive and negative terminals expecting to see somewhere between 12 and 24 vdc but nothing!

Could that be the problem? or should I go ahead with your checks above?

Many thanks

 

[Seadog]

If you can measure that ac voltage at the rectifier but no output, then it would certainly seem to be. You are changing to a dc range on your meter I assume?

 

[eddie49]

As far as I understood, the small transformer and the bridge rectifier supply power for the relay only ( the relay is off-board in this case ), which then applies mains power to the welding transformer. All that is working, the welder is turning on and the wirefeed motor is turning, it's just that the speed control pot has no effect. I thought that only the speed control part of the PCB needs to be investigated.

Regarding your question in post #16 above:

I think the dedicated power supply mod makes sense - does this do away with the PCB/controller?

The PCB will always be required in order to create and control the voltage for the on/off relay.

The new 24v power from an independent stabilised supply for the wirefeed motor, added to avoid voltage fluctuations when the arc is struck, could be routed through the original speed control circuit on the PCB. However, the one on this PCB is really crude. The solution is to fit a modern Pulse-width Modulated ( PWM ) controller:
https://www.ebay.co.uk/itm/3A-DC-6V...trol-Switch-Controller-Module-MO/153887474936
This runs the motor with pulses at the full 24 volts, so that maximum torque is available all the time. The speed is controlled by varying the effective "on" time of these pulses. It gives a smooth and controllable speed over a wide range