Bosch Building Technologies

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    How to Select a Replace head for the MX280 or MX250


    MX250 and MX250TH Multiplex Photoelectric Smoke Detectors are designed for use with the DS7400Xi series Control Communicators with a DS7430 or DS7436 Multiplex expansion Module installed. The DS7400Xi
    requires ROM Version 3.09 or greater. The DS9400M AddressiFire 255 Series Fire Alarm Control/Communicator or the DS9400i equipped with a
    DS9431. The DS9400i and DS9400M must have software revision 2.0 or greater.

    The MX250 and MX250TH are UL Listed, open-area multiplex
    photoelectric smoke detectors. The MX250TH has a built-in 135°F
    ±5°F (57°C ±2.7°C) heat detector.
    For commercial and industrial installations, 30 ft. (9.2 m) spacing
    between detectors is recommended (in accordance with NFPA 72).
    An LED indicator flashes every 3 to 8 seconds to verify that the detector
    has power and that the smoke sampling circuitry is functioning. The
    LED will flash at least once per second in the event of an alarm,
    allowing the user easy verification of individual detector alarms. The
    detector will automatically reset after the alarm condition has been


    The MX280 was replaced  with a MX250,  this caused the every  point on the Mux Buss of the DS7400XI to go into trouble.

    The MX250 and MX250TH Multiplex Photoelectric Smoke Detectors requires a MXB2W detector base. When installing the MXB2W the diode is NOT needed with the MX250 Series. Re-installing the diode on the MXB2W Base may cause every  point on the Mux Buss to go into trouble if installed incorrectly. Please do not use the diode with any multiplex devices with dip switches.

    Note: Todays Replacement (June 2018) for either MX280 or MX250 is the D7050, D7050TH and the Base is a D7050-B6.

    Part numbers MX280, MX280TH, MX250, MX250TH, MX2B, D7050, D7050TH, D7050-B6

    Version history
    Last update:
    ‎06-12-2018 10:03 PM
    Updated by: