Q3: What are the usual troubleshooting steps when the UPS displays 'Fan Fail-Set' alarm?
A: The usual troubleshooting steps when the UPS displays ‘Fan Fail-Set’ alarm are as follows:
1) Use a jumper cap to short-circuit the power signal interface of the fan power board, and test interfaces 1—n+1 in sequence.
If there are no alarms, it is normal. If there are alarms, the source of the fault needs to be identified. The source of the fault can be determined by replacing the fan or by interface testing (as shown in Figure 2).

Figure 2

2) If the source of the fault cannot be determined in the first step, continue to check:

① Fan power supply board:
J1: Fan PWM signal and LED indicators signal, power supply (as shown in Figure 3 below)

Figure 3

② Check if the auxiliary power board is faulty: If the power board is supplying power normally, its LED light will light up (as shown in Figure 4 below).

Figure 4

3) If the source of the fault cannot be determined in the second step, further checks are required:
① Replace the monitoring board
② Replace the cable connecting the monitoring board to the fan power board.