Why isn't my 748 siren working?

We will be discussing multiple reasons as to why the 748 siren is not working.

The 748 siren is a wired dual tone siren for use on a compatible wired alarm system. With the ability to produce tones up to 119dB the 748 is one of the loudest sirens Honeywell has produced. Dual tone can be achieved by wiring the siren to the panel in the correct fashion - Red & Black = Warble (dual) tone, Yellow & Black = Steady Tone.The siren can be used indoors or outdoors, as the unit is weather resistant, and it has an internal tamper switch that can notify the panel if anything or anyone attempts to remove or disable the siren. The 748 uses a maximum of 1.2 Amps of current at 12 VDC. Honeywell realizes this is a large amount of power, so they’ve also created the 748LC. The 748LC is almost identical to the 748, except that its maximum volume is 112dB and it only uses 550mA in its operation.

There are many reasons as to why a 748 may not be producing sound. The units draw a large amount of power at 1.2 Amps. If the system is going to be using multiple sound devices, their power draw will need to be added together and checked against the total available power supplied by the system. As an example, a Honeywell Vista 21IP only has 2 Amps available on its bell output. If the sounders attached to the bell circuit will draw more than 2 Amps, an auxiliary power supply can be added to provide additional power.

Incorrect wiring can also cause the 748 not to sound. The siren will need either the Red & Black leads, or the Yellow & Black leads connected to the powered bell output on the main alarm system. The Black wire is the common negative for either sound configuration, and will need to be connected to the Negative bell terminal. The Red or Yellow wire will then be attached to the positive terminal of the bell output. The white Normally Closed tamper circuit wires attached to the unit, can be wired into an alarm zone to provide supervision of the unit via its internal tamper switch. This is recommended, in particular, for outdoor installations, where the siren may be visible and accessible.

On Honeywell wired Vista panels, the siren receives most of its available 2 Amps of current from the backup battery. If there is no backup battery, or if the battery installed is not charged, or is not holding up under load, the siren will not sound properly. Installing a fresh battery, or replacing the old battery with a fresh one will remedy this issue. If you have a different type of system, it’s recommended to check the install manual to see if the battery provides siren power.

Specs:

Current - 1.2 Amps Max, at 12VDC

Sound Rating - Up to 119 db at 12VDC at 1 meter

Tones - Steady or Warble