Snap on pro mig 186 problems

[PhilKeith]

Evening all, been using my brother in laws mig and I'd like to get her up and running again before he wants it back I've got power on and the fans running but I've got no wire feed, no spark and no gas coming through? Just fed a new coil in this afternoon, picked up my gear went to weld and nothing, any ideas? It's been cutting out a few times today on the thermostat but then its ok after 10mins or so. Can't see any internal fuse.
Any help/pointers greatly appreciated.
Cheers
Phil

 

[Hutcho]

Does the contactor clunk ? That the black square thing above the fan .

 

[PhilKeith]

Not when the triggers pulled, by manually engaging the contactor we get a very faint clunk and buzz to the left of the unit but it still doesn't do anything else

 

[roofman]

Start at the top and check trigger switch on gun

 

[eddie49]

The auxiliary power transformer, mounted on the back of the chassis, top centre in your second photo, should have AC mains power when the welder is initially powered on. There should be about 24v AC coming from the secondary. This is fed to the control printed circuit board on the left. It is rectified there, and then runs the control logic and the wirefeed motor, via the speed controller.
As a first step, check the power in and output from that small transformer. There may be a fuse in the circuit, near the transformer or on the PCB.

If they run on 24v DC, the operating coils of the contactor and the gas valve will be supplied by the auxiliary power, switched via a relay or an electronic component on the PCB. Alternatively, if the coil voltage of one or both of those components is 230v AC, a relay or a TRIAC triggered by an optocoupler may be used.

As others have suggested, confirm that the torch trigger switch works. You can bypass that switch by unplugging the torch and replacing it with a simple wire jumper inserted into the two small sockets that accept the torch cable pins on the Eurotorch socket.

With the contactor closed manually, the main welding transformer will be powered on, and so it should be possible to strike an arc at the tip of the MIG wire, even though the wirefeed motor will not run.

 

[PhilKeith]

Quick update, stripped the torch down and one of the spade ends on the back of trigger switch had been mangled at some point and had come loose, wire feed and gas is back on but no arc?
Cheers
Phil

 

[Hutcho]

Is the contactor working when trigger pulled now ? If not you need to look at what voltage is meant to be switching it on - and if you get voltage at the contactor but it don’t pull down then it needs a new one

 

[Hutcho]

Is the contactor working when trigger pulled now ? If not you need to look at what voltage is meant to be switching it on - and if you get voltage at the contactor but it don’t pull down then it needs a new one

Might be worth just undoing one terminal at a time and clean them up on the contactor - I’ve had it before where it worked but the terminals was rusted and no contact could be made .

 

[PhilKeith]

Yes the contactors working now and pulling down when the trigger is pulled, can't see anything else obvious under the casing that could be causing the problem

 

[Hutcho]

Can you hear the transformer come on ? Set your meter to ac and put test leads on the ones circled - press trigger and see if you get voltage - it should change when you alter the settings on front .