Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
How did you change the windings, that is open the laminate core and replace.
The minute you compromise the physical structure and windings of a mains transformer, you need to have its insulation tested and PLEASE power it through a RCD switch.
(I don't mean DMM resistance measurement, I mean 500Vac resistance check)
This also worries me;How will that give you more voltage or current or power.
The circuit board contains this circuit:
Except that the diodes are all contained in a bridge rectifier IC from a tv circuit board.
The bridge rectifier is rated fro 250V AC because I got the datasheet from the part number.
The way they weld the laminated iron core together, on the outside faces, already compromises the iron core.
But apparently on the outside faces of the iron core the electrical paths do not cause significant problems with eddy currents.
So applying an angle grinder along those welds does not change the state of the iron core significantly.
Look its going to power a Tesla coil occasionally and I may muck around with it for an hour or two and then not use it for days.
I am not using this to power my power tools etc for 8 hours straight.