A test device is provided. The test device includes test components, power supplies, an alternating current (AC) power detection circuit and an alert module. The power supplies convert an AC power through a first wire, a second wire and an earth wire to a direct current (DC) power and supply the DC power to the test components. The AC power detection circuit receives the AC power through the first wire, the second wire and the earth wire to determine whether both of voltage differences between the first wire and the earth wire and between the second wire and the earth wire is outside of respective predetermined ranges. When both of the voltage differences are outside of the corresponding predetermined range, the AC power detection circuit controls the alert module to generate an alerting signal.

A magnet fixing implement for fixing a magnet for rotation angle detection, attached to a rotation center portion of an indicator needle of an analog meter, includes a main body, a magnet holder provided on an upper surface of the main body, and configured to hold the magnet at a rotation center of the indicator needle, a slit formed in the main body in a flat shape perpendicular to the rotation center, and configured to accommodate the rotation center portion of the indicator needle, a rotation shaft holder provided below the slit of the main body, and configured to hold a rotation shaft of the indicator needle, and an indicator needle restricting portion protruding toward an outer side from an outer peripheral edge of the main body, and configured to restrict a rotation of the indicator needle with respect to the main body.

A magnet fixing implement for fixing a magnet for rotation angle detection, attached to a rotation center portion of an indicator needle of an analog meter, includes a main body, a magnet holder provided on an upper surface of the main body, and configured to hold the magnet at a rotation center of the indicator needle, a slit formed in the main body in a flat shape perpendicular to the rotation center, and configured to accommodate the rotation center portion of the indicator needle, a rotation shaft holder provided below the slit of the main body, and configured to hold a rotation shaft of the indicator needle, and an indicator needle restricting portion protruding toward an outer side from an outer peripheral edge of the main body, and configured to restrict a rotation of the indicator needle with respect to the main body.