Alarm priority: Fire broadcast must have the highest priority, and any operation (such as manual emergency button, fire linkage triggering) should immediately occupy the audio channel.
Backup power switching time: From the loss of the main power supply to the takeover of the backup power supply, the equipment should operate without interruption (or the interruption time should be less than the specified value, usually within 100ms). DCS design meets this requirement.
Speaker line monitoring: Even if the system is in standby mode, the fault detection circuit must continue to operate. Therefore, when conducting line maintenance, the monitoring of the corresponding channel should be temporarily blocked through software first, otherwise it will continue to trigger fault alarms.
Simplified process for acceptance testing:
Disconnect the main power supply, confirm that the device continues to operate and the "main power failure" indicator light is on.
Short circuit one speaker output terminal (analog short circuit), wait for 1-2 seconds, and check if the DCS reports a "line short circuit" fault in that zone.
Press the emergency button on the front panel to verify that all preset zones are playing evacuation voice at sufficient sound pressure levels.

Typical Troubleshooting Table
Troubleshooting steps for possible causes of fault phenomena
The device does not start, all indicator lights are off, the main power is cut off, the fuse is blown, and the backup power is exhausted. 1. Check the AC input and plug; 2. Replace the 2A fuse at the rear of the chassis (spare parts are included with the machine); 3. Measure the voltage of the backup battery (should be>21.5V)
A certain partition has no sound, but there is no fault alarm. The amplifier channel is not assigned, the volume is turned off, and the speaker cable is disconnected. 1. Confirm in the software that the partition is enabled and assigned a sound source; 2. Check the volume knob of the front panel partition; 3. Use a multimeter to measure the resistance between speaker wires (which should be several k Ω to several tens of k Ω, and if it is infinite, it will be disconnected)
DCS continues to alarm for "speaker line fault". The actual fault of the line, the load is too small (monitoring may misjudge when<250W), and the terminal resistance is not connected. 1. Check the line in sections; If the actual load is less than 250W and still reports a false alarm, you can try increasing the false load resistance (10k Ω/2W parallel at the end of the line); 3. Disable the channel monitoring in the software (only applicable in situations where EN54 is not required)
Automatic volume control (AVC) ineffective noise detector not powered, sensitivity switch set incorrectly, noise detector position incorrect 1. Check if the detector is powered by the DC 24V output of DCS; 2. Confirm that the position of the backplane switch matches the output level of the detector; 3. Move the detector to a location that represents the average noise in the area (avoiding the air conditioning vents)
Network paging microphone has no response due to IP address conflicts, VLAN isolation, network packet loss, and incompatibility with DCS firmware version. 1. Use ping command to test connectivity; 2. Check the port configuration of the switch; 3. Ensure that both DCS and microphone are upgraded to the latest firmware version
Emergency broadcast cannot trigger fire linkage light dry contact output wiring error, output not configured in software, external relay coil without freewheeling diode. 1. Check the output contact (NO/NC/COM) wiring; 2. In the "event linkage" setting, associate the emergency mode with the specified output port; If an external inductive load (such as a relay) is connected, please parallel a freewheeling diode (such as 1N4007), otherwise it may damage the contacts
Maintenance and spare parts recommendations
6.1 Regular inspection items (recommended every six months)
Battery capacity test: Disconnect the main power supply and let the system run only from the backup power supply for 30 minutes, observing the voltage drop. If the terminal voltage of the battery rapidly drops below 21V, the battery should be replaced.
Speaker circuit insulation test: Use a 500V megohmmeter to measure the insulation resistance between each pair of speaker wires and the ground, which should be>1M Ω. Below this value, there may be cable damage or moisture.
Emergency mode function verification: Manually trigger the emergency button without notifying all personnel (to avoid panic), confirm that the evacuation voice is broadcasting normally, the alarm light is on, and the dry contact output action is activated.
Clean the dust screen of the air inlet: There is a ventilation fan inside the DCS chassis, and dust accumulation on the dust screen can cause poor heat dissipation, leading to excessive internal temperature (although there is no clear temperature fault code, long-term high temperature shortens the life of electrolytic capacitors).
6.2 Spare parts list (recommended to be kept on site)
Spare parts model/specification quantity