UTC Fire & Security Americas Corporation Inc 840B-SHK User Manual

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The Learn Mode Shock Sensor has the following three main 
functions:

•

To detect the vibrations made by an intruder trying to 
break a window or door.

•

To detect a window or door opening.

•

To detect tamper situations, such as an intruder remov-
ing the sensor cover or the sensor from the wall.

Vibrations cause a momentary open circuit in the shock ele-
ment of the sensor. The circuit closes again when the vibra-
tion stops. The sensor microcontroller “sees” the open/close 
action as a pulse, causing the sensor to transmit an alarm 
signal. The sensor has two different detection modes:

•

Gross Attack - detect a violent blow sufficient in length to 
trip sensor.

•

Pulse Count - detect a sufficient number of less violent 
blows (rapping or tapping).

The sensor includes an internal magnetic reed switch that 
must be disabled if it is not used.

Extend the battery life of the sensor by adding a second 3-
volt lithium battery.

•

Learn the sensor before adjusting the shock sensitivity. 
The sensor is shipped with the reed switch enabled and 
open, and this is how it must be learned.

•

Before permanently mounting the sensor, test it at the 
intended location to make sure that the panel can 
receive sensor signal transmissions. The sensor is an 
RF device and there may be blind or non-operational 
locations within the installation. Normally, these can be 
overcome by moving the sensor or receiver. 

•

Always mount the shock sensor so that the detector is on 
the frame and not on the glass. See Figure 2 for mount-
ing locations.

•

Mount the sensor in a location where the structure can 
transmit vibrations to the sensor.

•

The sensor can be mounted on a vertical surface or on a 
horizontal (flat) surface.

•

Make sure the window fits snugly in the frame and 
doesn’t move or rattle.

•

Hold the sensor against the frame to make sure the sen-
sor base fits on the surface area of the frame and doesn’t 
extend over the surface edges.

Tools and Supplies
•

Control panel installation instructions

•

Phillips screwdriver

•

Slotted screwdriver (to pry off the cover)

•

Two #6 x 2 cm flathead screws for mounting the sensor 
(included)

•

Two #6 x 1.5 cm screws for mounting the magnet 
(included)

Document No. 466-2023  Rev. A

September 2003