Rice Lake SURVIVOR 1700HE Weigh Module Kit - Manual (Page 13)

Troubleshooting 9
5.0 Troubleshooting
If the system powers up and gives some type of stable digital readout that varies with
the load on the system, any system problems are probably caused by factors other
than the load cells. The load cells are often blamed for a malfunctioning system, but
90% of the time, the problem lies elsewhere. Look for mechanical causes for your
problem first.
If the system can be calibrated but doesn’t return to zero, loses calibration, or demon-
strates non-linearity or non-repeatability, see the following chart for possible causes
and do the following checks.
1.
Check load cell mount for debris restricting load cell movement or debris
between scale and structure.
2. Check that tank/vessel and mounts are plumb, level, and square at critical areas.
3. Check all piping and conduit for connections which restrict vessel movement.
4. If check rods are used, loosen all connections to finger tight only for testing.
5. Check load cell cables for physical or water damage.
6. Check all electrical connections, especially in the junction box.
If the problem still is not found:
7.
Check possible indicator malfunction by using a load cell simulator to input a
known good signal into the indicator.
8. Disconnect each load cell’s signal leads at the junction box and check individual
load cell outputs with a multimeter. Then check input/output impedances for
comparison with load cell manufacturer’s specifications.
If after all these checks the problem still cannot be isolated, reconnect all but one load
cell. Replace load cell with a load cell simulator. Alternate so that each load cell is
individually disconnected and replaced with a simulator. If there is a problem with a
particular load cell, the symptom should disappear when that load cell is disconnected
and replaced with simulator.
Symptom Possible Cause
No return to zero Mechanical binding or debris in seals or under load cells
May have lost system calibration
Non-linearity Thermal expansion or deflection under load causing binding
or side load.
Non-repeatability Loose load cell mount
Drifting caused by moisture
Load cell overload or shack damage
Mechanical binding
Lost calibration Out of level or plumb
Moisture problem
Mechanical binding
Drifting readout Moisture in junction box, cables or load cells
Mechanical binding
Table 1: Troubleshooting Chart