After fitting new fuses welder still does not spark. Lights up when switched on and wire feeds but will not spark. I have cleaned and checked the earth cable/clamp which is fine. Anybody got any ideas?
When you press the trigger on the MIG torch do you hear the gas solenoid open, and the main Contactor ( heavy duty relay ) "clunk" on?
The Contactor may have a manual-on push-button in the centre of the top. If so, try pressing that button ( e.g. with an insulated screwdriver ) and test if you can get an arc at the MIG tip.
If the wire feeds when you press the torch trigger, that means the auxiliary supply ( small 24v transformer ) is OK, and the PCB sees the trigger contacts closing, The gas solenoid should switch on - this may be audible, and the main Contactor should pull in - you would definitely hear this if it happens. If it is not pulling in, then either the power is not being sent to it from the PCB, or the operating coil on the Contactor has burnt out. There may be a label to show the coil voltage - 230v AC, or 24v DC. Check for that voltage across the coil when pressing the torch trigger. With the machine disconnected, use an Ohmmeter to check if the Contactor coil has gone open-circuit.
Even if the Contactor does not close when pressing the torch trigger, you should be able to close it manually with the button, and then you should get an arc at the torch tip ( with the machine on, trigger pressed, and the manual button held in ).