Hi thank you for your advice I have recently checked over the machine the wire feed works but no arc from the torch but have noticed what looks like a relay or switch unit the centre is grey that you can push in when this is done it will arc? How should this work could this be the faulty culprit.Hello and welcome to the Forum.
There's plenty of earlier threads on here about these venerable beasts. Use the Search facility at the top right, look for "BOC Transmig".
These welders were made with high-quality industrial-strength components, but not put together very well. Check for poor soldered joints and loose or corroded connections. After a lot of use, the carbon brush on the main Variac may have worn away and not be making full contact with the winding.
Hi Eddie thank you for your help have been busy with the machine trying to get it to work as a result not very well still, I have tried a new torch, new wire checking connections and this is what I get in the image.That's good that you are making progress in getting this worthy machine running. The top few layers on the rusty MIG wire spool can be discarded, and the wire under that may be bright and clean.
However, even if rusty, the wire should still arc strongly and melt. The fault you are now seeing corresponds with the original description of the problem - there is a lack of "power". This could be due to low voltage at the torch tip ( should be 15 to 30v DC ), or a high resistance somewhere preventing enough current flowing ( 30 Amps upwards ). This high resistance can be due to a loose, corroded, or burnt connection.
With the unique circuit of the Transmig, I would start by checking the spring-loaded carbon brush that should make firm contact with the circular winding of the variable transformer. There are two of these components, generically known as "Variacs". The larger one controls welding power, the other varies the speed of the AC wirefeed motor.
Rear view of a Variac:
View attachment 432741
On this example, the carbon brush is on the rotating arm, under the plate with two screws at bottom left. It should press onto the bare part of the winding, and that enamelled copper wire coil must be intact with no burns or breaks.