The AMADA MM-400B Weld Checker is a sophisticated quality control device for resistance welding, capable of monitoring current, voltage, welding time, force, and displacement. It is compatible with various welders, including AC, AC/DC inverter, transistor, and capacitor types. Operation is intuitive via a 5.7-inch color touch panel, allowing setting of up to 4 waveforms and 10 parameters, with ISO17657 compliance. The MM-400B-02-05 model enhances capabilities by offering long-time current and voltage measurement up to 10 seconds in AC/DC welding, and absolute displacement measurement for pre-weld workpiece thickness and quality determination. An envelope function enables real-time monitoring by comparing actual waveforms with set tolerance waveforms. Monitored data and waveforms can be saved internally or to external USB, with connectivity options including RS-232C, RS-485, and Ethernet for data communication. Its integrated judgment and control system utilizes force and displacement sensors built into the weld head for in-production monitoring, waveform display, and quality determination. This system features a 3-output Weld Stop function for precise control. Additionally, external inputs (voltage ±10V, current 4-20mA) allow for the integration of other sensors, such as temperature, to measure, display waveforms, and output quality judgments.