Simplex 565-831 — replacement printed circuit board assembly for a Simplex 4098 Series duct smoke housing. It is a bare board, not a detector and not a housing.
In these housings the PCB assembly sits in the wiring compartment of the base, below the head, carrying the field terminals, the status LED and, on addressable models, the address switch. Head, base, sampling tubes and remote relays are separate numbers.
- Simplex installation instructions 574-776 name the 4098-9755 the Two-Wire Duct Sensor and the 4098-9756 the Four-Wire Duct Sensor, both addressable on MAPNET II or IDNet
- It names the 4098-9685 and 4098-9688 Duct Detectors, conventional two-wire IDC devices and a different family
- Field wiring is #12 to #18 AWG through either of two 3/4 " entries
- On the 4098-9755 and 4098-9756 the board carries DIP switch SW2, setting the address
- 4098-9755 circuit: MAPNET II or IDNet, 24 to 40 VDC, 400 µA typical
Read the model number on the housing label first: the Simplex split between Duct Sensor and Duct Detector decides the board. No Simplex document read here names 565-831 against a housing.
