> A G3 case with stickers on the back saying 115V and to use a 0,25A fuse.

Inside the case

> the power supply PCB clearly says and is an "A-100 Power Supply II" but

has the square

> transformer on it.

The pcb board labelled "A-100 Power Supply II" is suitable for both versions
of transformers. During the transition period (i.e. the time when two types
of supplies were available) both types of transformers could be mounted to
the board labelled "A-100 Power Supply II".

Best wishes
Dieter Doepfer