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Model U-1400 Operations Manual Rev Apr 2020 Page
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Section 8
Maintenance and Troubleshooting
The Reno A&E Model U-1400 Detector requires no maintenance. If you are having problems with your Model U-
1400 detector, use the troubleshooting tips below to help determine the cause of the problem.
8.1
BASIC TROUBLESHOOTING TIPS
Detector Enclosure Checks:
Verify correct input voltage to the detector.
Check the detector diagnostics. If there is a current loop failure or the loop fail memory shows a loop failure has
occurred, the problem is probably not related to the detector module.
Check the loop / lead-in cable resistance of the detect loops and the check loops. A value greater than five
Ohms is an indication of a splice or connection problem or a broken loop wire.
Disconnect the detect loop or check loop from the detector. Use a 500 VDC Megger to measure the resistance
from one of the loop wires to earth ground. It should be greater than 50 megOhms. If lower, separate the splice
at the pull box and isolate the problem to the loop or lead-in cable.
Verify all terminal screws are tight.
Inspect all loop connections in the detector enclosure, especially crimped lug connections. If suspect, solder the
lugs to the wire.
If the lightening or surge suppression devices on the loop inputs in the detector enclosure are suspect, remove or
replace them.
Check for places in the detector enclosure where the harness wires or lead-in cable may be pinched or chaffed.
Make sure that each pair of interconnect (lead-in) wires for the loop(s) are individually twisted together.
Field Checks:
Inspect the loop. Look for exposed wires, debris pressed into the loop wires, pavement shifts, etc.
Check splices in the pull box. They must be soldered and waterproofed. DO NOT USE WIRE NUTS.
Check that each set of loop lead-in wires in each pull box is twisted together [six (6) twists per foot, minimum]
and that lead-in lengths are not excessive.
