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How to Replace Discontinued BRK 660MBX, 670MBX, and 690MBX Smoke & Heat Alarms

To replace your discontinued BRK 660MBX, 670MBX, and 690MBX mains-powered alarms (with replaceable alkaline backup batteries) with an easichange replacement alarm we recommend following these simple installation steps or the instructions in the videos below.


Simple Step-by-Step Installation Process

Due to the dangers of working with live electricity, only undertake this installation if you can properly identify and turn off power to all circuits that supply all of your interlinked alarms. The interlink wire can carry a live electric current between alarms if they are powered from different circuits. If there is any uncertainty, seek help from a professional electrician.

  1. Turn off the power at your fuse box or consumer unit.
    • Take care to turn off all circuits powering any of your alarms, as the interlink wire can carry a live electric current.
  2. Remove your old BRK smoke or heat alarm from its baseplate by twisting and the unplugging the connector.
  3. Insert the supplied 9V battery into your easichange® replacement alarm and close the unit securely.
    • Test the alarm to make sure it is powered up from the backup battery!
  4. Install the alarm on your old BRK baseplate:
    • Connect the plug so that the wires of the connector line up with the pins on the alarm.
    • Twist the alarm fully onto the base.
  5. Repeat steps 2 to 4 for all of your old BRK alarms.
    • We recommend replacing all alarms in the system together to maintain optimum system operation; failing to do so may compromise interlink performance.
  6. Turn the power back on at the fuse box.
  7. Test each of your smoke alarms separately to ensure the whole system is functioning correctly. When you test one alarm, they should all sound, however it is important to press the test button on each alarm too.

Why Use Easichange® Replacements?

The SBBRKSM smoke alarm and SBBRKHE heat alarm have been specifically designed so that owners of BRK 600 (twist base) series fire alarms with alkaline backup batteries can quickly and easily swap out old detectors which have reached the end of their 10-year lifespan. Using the existing baseplate from your old BRK alarms means that you avoid having to redecorate or patch up where your old baseplates were located.

Alarms from different manufacturers have different size baseplates, which can leave visible marks where the old baseplate was installed, and use different connectors to prevent customers mixing incompatible alarms, requiring an electrician to rewire and swap all of them. Thanks to the specially designed easichange® adaptor plate, which comes pre-assembled, there is no need for any DIY skills or to pay an electrician to rewire the alarms.

Compatibility with BRK Models

These easichange® smoke and heat alarms are designed to be suitable replacements for the following BRK 600 series models with alkaline backup batteries:

BRK Model

Alarm Type

Base Type

Easichange® Replacement


Smoke, Optical, Alkaline backup battery




Smoke, Ionisation, Alkaline backup battery



Heat, Alkaline backup battery



To help identify which models you have, please see our guide on the BRK 600 & 700 series.

Product Manuals

You can download PDF copies of the easichange® replacement alarm instructions here:

Product manuals for your old BRK alarms can be found here:

We also have a range of other videos to help with removing, replacing, and maintaining BRK alarms and these easichange® replacements.


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