1. Huawei Technologies Co.
Ltd. (2016). OptiX RTN 950A Radio Transmission System V100R008C10 Installation Guide. Document Issue 15. In the section "Replacing an IFU2 Board"
the procedure explicitly states: "1. Query the running status of the board to be replaced. If the board is running
power off the ODU that is connected to the board. ... 3. Disconnect the IF cable from the IF port on the board." This directly confirms that the ODU must be powered off before the IF cable is disconnected from the IF board.
2. Huawei Technologies Co.
Ltd. (2017). OptiX RTN 980 Radio Transmission System V100R009C10 Installation Guide. Document Issue 12. In the section "Replacing an ODU"
the procedure includes the step "Power off the ODU" before instructing the technician to "Disconnect the IF cable from the IF port on the ODU." While this describes disconnection at the ODU end
the principle of de-energizing the line before breaking the physical connection is identical and applies to disconnection at the IF board as well.
3. Huawei Technologies Co.
Ltd. (2019). General Safety Precautions. Document Version 1.18. This document outlines fundamental safety principles for handling Huawei equipment. Section 1.3 "Electrical Safety" warns against connecting or disconnecting power cables with the power on
stating: "Before connecting or disconnecting a power cable
turn off the power switch." The IF cable functions as a power cable for the ODU
making this general precaution directly applicable.