Which of the following is a common troubleshooting step for cad cell failures?

When troubleshooting cad cell failures, common practices involve examining multiple aspects of the cad cell's functionality to ensure it operates effectively and reliably. Inspecting electrical connections is critical because loose, corroded, or damaged connections can prevent the cad cell from receiving the necessary signals or power, leading to malfunction.

Replacing the cad cell itself may be necessary when a more in-depth failure is suspected or when maintenance efforts have not resolved any issues, especially if the cad cell is determined to be defective or has reached the end of its lifespan.

Cleaning the lens surface is also an important step, as dirt, soot, or other contaminants can obstruct the sensor's ability to detect flame properly. A clean lens ensures that the cad cell can sense the flame as designed, which is essential for safe and efficient operation.

Incorporating all these steps provides a comprehensive approach to addressing cad cell issues, making "All of the above" the most appropriate response. This thorough method ensures that no stone is left unturned when diagnosing problems with the cad cell.