The Schlumberger 9720000379 REV 4 Test Control Board is a controller module used in industrial test equipment to manage sensor inputs, actuator outputs, and data communication with host systems. Common failure modes reported for this board include burnt or cracked surface‑mount components on the power regulation section, shorted trace paths between I/O channels, and intermittent faults in the serial communication interfaces (e.g., RS‑232/RS‑485). Initial troubleshooting should verify that the supply rails (typically 12 VDC and +5 V) are within spec, inspect for visible damage or solder bridges on the power regulator area, and test the integrity of I/O connections with a multimeter or logic probe before proceeding to component replacement.[oss-gpt-20b]