problem with transformer

hello people… i’m having a sort of a problem with guitar pedal power suplly. The first winding of one of the transformers is done fourfould section decreasing and seems to work just on one direction. If i just use a diode crossing the positive direction will iot blow in case of reversion?

thanks. the transformer model is a TEZ 2,0D sec 12, 0,83 sec2 12v 0,083A.