Security System Repair

Security system repair is often simple. By keeping your security system or burglar alarm in top operating condition you’ll not only sleep better, your neighbors will too. This Fix-It Guide tells how a security system works, what often goes wrong, how to identify a security system problem, and what parts and tools you will need to fix your system. It then gives instructions on how to test a security system wired sensor, as well as how to perform magnetic switch sensor replacement, plunger switch sensor replacement, and vibration glass-break detector replacement.

How Does a Security System Work?

Security System Repair

The central control unit has wire connections from each of the sensors.

A security system is a set of sensors designed to trigger an alarm if someone unauthorized tries to gain entry into a home. Sensors placed at strategic locations throughout the house or an automobile, check current status (okay, not okay) and report back to the central control unit. The control unit keeps track of all the sensors and their current status. If it decides there is a problem, it activates an audible alarm and/or an automatic telephone dialer that can summon help by phone.

The two primary types of systems used in home security are wired and wireless. A wired system is connected by small, low-voltage wires routed discretely throughout the house. A wireless model uses tiny radio transmitters to signal the central control unit when activated. Control units typically have a battery backup activated if there is a power failure or if the wires are cut.

What Can Go Wrong with a Security System?

Security System Repair

You also can install single sensor controls that manage security at a single location such as a specific door or window.

False alarms happen. Some are due to user error while others are caused by nonthreatening events such as high winds or a thunderstorm. Other than that, most security systems have self-diagnostics built in that can be used to determine the cause of a problem.

Fix-It Tip

If your security system has an entry code (most home alarm systems do), make sure it’s one you can easily remember, such as a birth date, social security number suffix, or keyboard pattern. And, of course, make sure it’s easy for other members of your household to remember. There’s no panic like standing at the system keypad trying to disarm an alarm when you’re not sure of the code–at two in the morning!

How Can I Identify a Security System Problem?

Security System Repair

Some security systems include a video camera to monitor outside the front door or in a child’s room.

  • If the system triggers frequent false alarms, verify the code and run a diagnostics test on the system (check the owner’s manual). If the alarm rings again, check the wiring and sensors. Clean or tighten wire connections at sensors and the control unit. Replace a worn-out microwave sensor. Check the sensitivity of all vibration- or motion-detecting sensors. Trim any tree or shrub branches that may hit a window with a vibration sensor. Make sure the lens on a passive infrared motion sensor is clean.
  • If you can’t arm the system, make sure that all doors and windows are closed and locked. Check for tripped sensors and replace any that are faulty.

Fix-It Tip

The owner’s manual for your security system is vital. Make sure you have it in a handy location and that at least one member of your household has read it thoroughly. If you purchase a system and have someone install it, ask questions while they work to learn what they don’t tell you in the manual. If you lease the system or pay for supporting services, let the alarm company service the unit.

What Do I Need for Security System Repair?

The most common parts that fail are the sensors. Make sure replacement sensors are exact substitutes for the ailing sensor. You can buy them from a security company or an electronics store. Here are some basic tools for fixing your security system:

  • Screwdrivers
  • Razor blade
  • Multimeter

What Are the Steps to Security System Repai?

Test a wired security system sensor:

  1. Disconnect one wire and activate the sensor.
  2. Set the multimeter on RX1 (resistance times 1) scale (resistance in ohms), touch the probe to the sensor’s terminal screws, and note the reading.
  3. Deactivate the sensor and run the test again. If the sensor is okay, one reading will be zero (no resistance) and the other infinity (no circuit). Replace the sensor if both readings are zero or infinity.

Replace a security system magnetic switch sensor:

  1. Turn the alarm controller off and disconnect power to the security system.
  2. Unscrew the magnet and switch, then detach the wires.
  3. Attach the wires to contacts in the new switch and screw the switch onto the window frame.
  4. With the window closed, align and install the magnet on the window sash.
  5. Set the multimeter on RX1 (resistance times 1) scale, touch the probe to the sensor’s terminal screws and note the reading.
  6. Activate the sensor and run the test again. If the sensor is okay, one reading will be zero (no resistance) and the other infinity (no circuit). Replace the sensor if both readings are zero or infinity.

Replace a security system plunger switch sensor:

  1. Disarm and turn off power to the security system.
  2. Unscrew the door frame switch and move it aside to access and remove contact screws.
  3. Attach the wires to the contact screws on new unit and install the new unit on the door frame along with the new plate.
  4. Set the multimeter on RX1 (resistance times 1) scale, touch the probe to the sensor’s terminal screws and note the reading.
  5. Activate the sensor and run the test again. If the sensor is okay, one reading will be zero (no resistance) and the other infinity (no circuit). Replace the sensor if both readings are zero or infinity.

Replace a security system vibration glass-break detector:

  1. Disarm and turn off power to the security system.
  2. Use a razor blade to remove the old unit.
  3. Remove the sensor’s wires and install them on the new sensor. Some are attached with screws while others require soldering.
  4. Adjust the sensor following the directions that accompany the unit.
  5. Set the multimeter on RX1 (resistance times 1) scale, touch the probe to the sensor’s terminal screws and note the reading.
  6. Activate the sensor and run the test again. If the sensor is okay, one reading will be zero (no resistance) and the other infinity (no circuit). Replace the sensor if both readings are zero or infinity.

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