My panel is displaying a trouble "Internal Fault" on a smoke detector
"Internal Fault" on a smoke means the device couldn't be calibrated by the panel.
- Clean the device by following the instructions below.
- Replace the head and send the defective head in for recalibration or replacement to the National Repair Center at 800-289-0096 x2220.
Cleaning the D323A or D324A
Remove and disassemble the sensor
Follow the steps in this section to prepare the sensor for cleaning:
- Remove the sensor from its base.
- Disassemble sensor by following the NSRT-A100 instructions found at the end of this page.
Note: The NSRT-A100 is a Hochiki part number and can be ordered by calling Hochiki sales support at 714-522-2246 or Hochiki technical support at 800-845-6692
Clean the sensor
CAUTION: Do not attempt to remove the insect screen. Follow the steps in this section to prepare the sensor for cleaning:
- Remove the Outer Cover of the sensor as specified on page 5 and set aside.
- Place the sensor in the palm of your left hand and grasp the Chamber Cover with your right hand. Twist the Chamber Cover counter clockwise until the Cover Tabs clear the Tab Catches. Lift and separate the Chamber Cover from the Optical Unit.
- Swab the Optical Unit with denatured alcohol using a small soft bristled brush.
- Use dry clean compressed air to dry the optical unit and to remove any remaining particles.
- Clean the Chamber Cover and Outer Cover in the same manner.
Reassemble the sensor.
Follow the steps in this section to reassemble the sensor.
- Locate the Alignment Arrows on both the Chamber Cover and the Optical Unit.
- Set the Chamber Cover onto the Optical Unit while making sure the Alignment Arrow 1 and Alignment Arrow 2 are aligned with one another.
- Holding the sensor in your left hand and grasping the Chamber Cover with your right hand, rotate the Chamber Cover clockwise until the Cover Tabs snap into the Tab Catches.
- Place the Outer Cover of the sensor nose down on a flat surface.
- Align the Outer Cover Keys with the Recess in the Outer Cover (two orientations are possible, only one will fit properly).
- With the Outer Cover Keys aligned with the Cover Recessed, press down firmly on the back of the sensor. The sensor will snap into the Outer Cover. The sensor is now ready to be returned to the base from which it was removed.
- The sensor should be re-tested by following the test procedure found in the control panel literature.
NOTE: If after testing, the sensor is not working within the prescribed range then return it to the manufacturer for servicing.
Sensor Cover Removal Instructions
This section explains how to remove the outer cover from the D323A and D324A by using the NSRT-A100.
Remove and disassemble the sensor
Follow the steps in this section for removal of the sensor cover:
- Place the sensor to be disassembled on the NSRT-A100 tool making sure that the Locator on the sensor is aligned as shown on the diagram.
- Using your thumb and index finger rotate the sensor back and forth until it drops into place on the NSRT-A100.
- Grasp the sensor firmly and rotate the sensor clockwise (approximately 30 deg.) until the Locator on the sensor lines up with the Mounting Ears of the NSRT-A100. The contact blades on the sensor will engage on the NSRT-A100 and will prevent further rotation.
- The sensor cover is now disengaged from the sensor body and can be removed by pulling the sensor cover away from the NSRT-A100.
- After the cover has been removed, refer to the sensor cleaning instructions to clean and reassemble the sensor.