An apparatus for testing electrical continuity of a surface mounted (SMT) electrical board includes: a printed wiring board having a first surface and an opposite second surface; a conductive signal line disposed on each of the first and second surfaces of the printed wiring board; an electrical component disposed on and electrically connected to the conductive signal line on the first surface; and a through hole extending through the printed wiring board and the conductive signal line on the second surface of the printed wiring board exposing a surface side of the conductive signal line facing the first surface of the printed wiring board. The through hole is unplated in an inside bore defining the through hole and the through hole allows direct access to the conductive signal line on the first surface to test continuity of the conductive signal line on the first surface connected to the electrical component from the second surface of the printed wiring board.