Troubleshooting For 955Qd - Ametek Gemco Brik 955QD Series Installation, Programming And Maintenance Manual

3.7: Troubleshooting for 955QD

Troubleshooting describes common problems that may occur when installing the LDT and offers possible
solutions to these problems. If, after reading this appendix, you are unable to resolve a problem, contact our
technical support department at 248-435-0700. Troubleshooting is divided into the following two groups:
• General Checks
• Power Supply
General Checks
Make sure that the magnet is located within the LDT's active stroke area. Captive magnet assemblies should
be positioned so that they can move freely over the entire area of the active stroke without binding or pushing
on the extrusion. Non-captive magnet assemblies should be situated so that the magnet is no further than
3/8" from the sensing surface at any point in the oating magnet assembly's movement.
NOTE: Ferromagnetic material (material readily magnetized) should be located no closer than 0.25" from
the sensing surface of the LDT. This includes mounting brackets, magnet spacers, magnet brackets, and
mounting screws. Ferromagnetic material can distort the magnetic eld, causing adverse operation or failure
of the LDT.
Check all LDT wires for continuity and/or shorts. It is preferable that the cable between the LDT and the
interface device be one continuous run. If you are using a junction box, it is highly recommended that the
splice junction box be free of AC and/or DC transient-producing lines. The shield should be carried through
the splice and terminated at the interface device end.
Power Supply Check
This section will help you to determine if your power supply is adequate for the LDT to operate properly, or
if the LDT's cable has a short or open.
In order for the 955QD to operate properly, the external power supply must provide a level between 10 to 30
VDC. A power supply providing voltage above this specied range may damage the LDT. A power supply
providing power below this specied range will not be sufcient to power the LDT. When powering more
than one Brik on a single power supply, remember that each Brik requires three (3) watts of power maximum
(1 watt typical). The amount of current draw will vary based on the input voltage used. To calculate the
current draw for a particular LDT, divide the LDT wattage by the input voltage. For example, 3 watts divided
by 24 VDC equals 125mA.
If your LDT is not operating properly, the LDT's cable may have an open or short, or the power supply is not
supplying sufcient power. To verify this, perform the following steps:
1. Turn the power supply off
2. Remove the mating connector from the LDT
3. Turn the power supply on
4. Using a digital voltmeter, check pins 1 (GND) and 2 (+) from the mating end of the cable for a
level between +10 and +30 VDC.
Installation, Programming and Maintenance Manual
Chapter 3: 955QD Overview
14