PURPOSE: To absorb automatically positional slippage between a transformer substrate and a head substrate to connect electrically them by forming elastic radial cuts around a hole on the head substrate to which a terminal pin stood on the transformer substrate should be inserted.

CONSTITUTION: A terminal pin 22 is stood on a rotary transformer substrate 7, and a head base substrate 8 to which a head substrate 23 is attached is provided with a hole 24, and a conductor plate 20' provided to cover the hole 24 is cut radially to form elastic tongue pieces 20'a. The pin 22 is pressed into cuts covering the hole 24, and variances of assembling precisions of the pin 22 and the hole 24 are absorbed by the flexure of the substrate 23. Consequently, substrates 23 and 7 are connected by setting a cylinder 9 onto a disc 5 merely, and the positional slippage is automatically absorbed by the simple structure, thus automatizing the assembling work and reducing the labor of this work.