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What problems are commonly encountered during the use of valve positioners? As is well known, valve positioners, as essential accessories for control valves, serve to regulate the operation of pneumatic control valves. Therefore, it is widely used in both domestic and industrial fields. However, valve positioners are bound to encounter some unexpected problems during use. Today, the technical team from Xi’an Pried Instrumentation will list the common issues that arise when using valve positioners, so as to help everyone better understand them during operation. Common Issue 1: The valve positioner cannot self-tune: When attempting to perform self-tuning on the valve positioner, it is found that the electrical angle displayed on the screen is not within the specified range; this requires us to be careful during installation so as not to go beyond the indicated range. Common Issue 2: No display on the LCD screen: Usually, we use a multimeter to measure the DC voltage at terminals 11 and 12, in order to check whether the positive and negative poles of the voltage are connected correctly. If there are no issues, we also need to confirm whether the voltage range for terminals 11 and 12 is between 8.2–8.7 V. If the voltage is found to be within this range, we can basically conclude that it is a problem with the motherboard; if the voltage is not within this range, then the issue lies with the DCS interface or the transmission cables. Common Issue 3: Actuator oscillation: Check for air leaks at the connections of 0UT1 and 0UT2 to the cylinder inlet pipes; set the operation mode to 1.3 manual mode, and verify whether one of the connections at 0UT1 and 0UT2 is leaking air continuously. If there is always air leakage, it may be due to a slight blockage inside the valve body of the valve positioner. If the valve positioner has no air leakage, but during manual operation the air output from one end remains unchanged between normal opening and accelerated opening modes, this can also cause oscillation. In the case of such a fault, we need to reset the valve positioner to its factory settings using option P11 in the menu, and then perform self-tuning again. Common issue 4: The cylinder does not respond to signals: We can set the operation mode to manual, and by using the increase and decrease buttons, we can check whether OUT1 and OUT2 generate any output. If both ports have alternating outputs, we can conclude that the problem lies with the cylinder or the load. If only one port outputs, or both ports output simultaneously, or one port keeps outputting, it indicates that there are impurities stuck inside the components of the valve positioner; in such cases, it is necessary to replace the positioner. Common Issue 5: Abnormal position feedback signal: Under normal circumstances, when using a multimeter to measure terminals 31 and 32, the DC voltage should be between 17-23V. If the voltage value is within this range, it is generally assumed to be a problem with the feedback circuit board; if the voltage value is not within this range, then the fault lies in the DCS interface or the transmission wires. Above are the common issues that arise during the use of valve positioners, as we have reviewed today. It is hoped that what we have learned today will help us diagnose the common problems with valve positioners correctly.