Instruction Manual

8
1080 N. Crooks Road • Clawson, MI 48017 • 800.635.0289 • 248.435.0700 • Fax [phone] • www.AMETEKAPT.com
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 1-800-635-0289.
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 fl 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 fi 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 955D to operate properly, the external
power supply must provide a level between 13.5 to
30 VDC. A power supply providing voltage above this
specifi ed range may damage the LDT. A power supply
providing power below this specifi ed range will not be
suffi cient to power the LDT. When powering more than
one BRIK on a single power supply, remember that each
BRIK requires 2.5 watts of power maximum. 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, 2.5
watts divided by 24 VDC equals 105mA.
If your LDT is not operating properly, the LDT’s cable
may have an open or short, or the power supply is not
supplying suffi 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 3 (GND) and
1 (+) from the mating end of the cable for a level
between +13.5 and +30 VDC.
If reading is between 13.5 and 30 VDC, turn power
supply off and go to step 7. If reading is below 13.5 VDC,
either your power supply is not providing enough power
or the LDT’s cable possibly has a short/open. Readings
of no voltage or minimal voltage (less than 5 volts) may
be due to short/open in the cable. If reading is NOT
between 13.5 and 30 VDC, go to step 5. If reading is
above 30 VDC, adjust power supply or replace.
5. Turn the power supply off.
6. Check the continuity of the individual wires of the
cable between the power supply and the LDT. Check
for continuity from one end of the cable to the other.
Also verify that no shorts exist between pins.
7. Reconnect the mating connector to the LDT.
8. Turn power supply on.
9. Using a digital voltmeter, check the power supply’s “+”
and “-” terminals for a voltage between
13.5 and 30 VDC.
Low voltage readings may indicate a power supply with
a wattage (current) rating that is too low. (Each LDT
requires 2.5 watts). If the cabling checks out in step 6
and your voltage is below 13.5 VDC, check your power
supply current rating. If voltage is between 13.5 to 30
VDC and the LDT is still inoperative, contact factory.
3.6 Troubleshooting for 955D