I've just retrieved one from an old microwave oven..Soon found the tinternet is full of schemes for rewinding and re-using these things -some mad cap and some ill informed..so..some questions..
First.setting aside the potential danger of using a tranny where the HV side is common'd to the core and perhaps the provided isolation may not be good enough for that connection to be lifted - What will the effect on regulation and efficiency if the transformer is used in reverse..ie as an approx 10:1 step down (UK version).
Next, what difference in performance if the magnetic shunt is not removed..ie what is it for ?
Finally..Even if the secondary is rewound for low volts/high current what will be the effect of the weld that shorts all the core plates together..ie will it ever make a decent transformer (for anything other than the purpose it was designed for ?

 

The magnetic shunt as it implies, shunts off or prevents ideal coupling between the primary and secondary, this acts as a form of current restriction, or regulator, for many applications such as spot welder etc, you would need the shunts removed.
Max.

 

The magnetic shunt as it implies, shunts off or prevents ideal coupling between the primary and secondary, this acts as a form of current restriction, or regulator, for many applications such as spot welder etc, you would need the shunts removed.
Max.

Thanks Max , fortunately that's easy to do..
As to the next question, don't worry. I wouldn't even consider it because all that extra inductance and resistance would surely make it a poor tranny.
I was really hoping someone knows what the effect of that weld which joins the E & I plates together and be must be an electrical short circuit of what I've always believed is the insulating surface of the core plates which prevents eddy currents. Otherwise a solid lump could be used..Anyone ?

 

No the lamination's are used to prevent eddy currents, the weld is to stop or prevent annoying buzz of vibrating lamination's when high current occurs.
Max.