PURPOSE: To obtain the signal changeover circuit with excellent cost performance by providing an external mount use external terminal to a clamp capacitor and using the external mount use external terminal for an external synchronizing signal input terminal in common so as to suppress increase in number of pins for common use.

CONSTITUTION: Signal changeover circuits 180, 190, 200 of the same configuration are in use. Two terminals 41b, 41r are used in common for terminals to which clamp capacitors Cb, Cr are externally mounted and terminals for external synchronizing signals H, V. When the signal changeover circuit 190 is in use, the external terminals 41r, 41b are used for the H, V terminals. When the circuit 200 is in use, the external terminals 41r, 41b are used for the connection terminals for the externally mounted capacitors. Thus, number of pins for circuit integration is reduced and the cost is reduced.