The screen displays: the number of people passing through 0 (1) does not change;

The number of alarms 0(1) does not change;

1.1, first open the main box, find the infrared board (Figure 7), and then measure the infrared emission 2pin line and infrared receiving 3pin line, the normal voltage 2pin line 2 feet is 0.8V, 3pin line 2 feet voltage (0 ~ 5V, in In the case of a person, the voltage becomes 5V. If the voltage of the 2nd pin of the 2pin line is 2.4V, it means that the soldering of this line is disconnected, for example, the 2nd pin of the 3pin line is 5V (if not passed) ), indicating that the infrared receiving probe connected to this line is bad or the infrared board is bad (generally, first change the infrared receiving probe, if not, replace the infrared board to resume normal use).