Sigma 900 MAX Refrigerated Sampler Instrument Manual

Page 130
Troubleshooting and Error Messages
8990apdx_tbl.fm
Appendix C
Downlook Ultrasonic Sensor Troubleshooting
Problems Causes Solutions
RS485 Time Out—Did not get a
reading with the specified time
allotted.
CPU is having trouble communicating
with the Ultrasonic board.
Wait a few minutes and see if the condition
goes away. If it continues there amy be a
problem in the Ultrasonic, Velocity, or
CPU board.
Difficulty receiving a velocity reading. Indicates an internal problem.
Loss of Ultrasonic as Level
Measuring Device.
Blown fuse on CPU board.
Replace fuse. The fuse is located in position
F1 under the gray ribbon cable that connects
at position J1.
Problem with the ultrasonic board. Replace if necessary.
U-Sonic Echo Loss—Flow Meter
Not Receiving a Return Echo
from the Ultrasonic Transducer.
Excessive foam on the water surface
causes sound waves to be absorbed
rather than reflected.
Check for excessive foam.
Sensor is knicked or cut or improperly
installed.
Check for knicks, cuts, and the
sensor installation.
Sensor must be level for proper return
of signals.
Make sure the ultrasonic transducer is level.
Convection currents are present which
varies the speed of sound.
Try shielding the transducer from convection
currents. Echo loss should not exceed more
than two hours.
Temperature calibration set up incorrectly.
Extreme high or low temperature
indicates a bad temperature transducer in
the temperature sensor.
Go through the temperature calibration
procedure and determine what the
temperature the unit is sensing. Replace
transducer if necessary.
U-Sonic Failure—No Signal from
the Ultrasonic Transducer.
Transducer is not connected.
Check the ultrasonic sensor connection on the
flow meter.
Cut or broken cable. Check for any knick or cuts in the cable.
Unusual temperature or inability to read
new calibrated level.
Re-calibrate the unit.
XDucer Ringing—False Return
Echo mask Real Echoes.
Liquid is too close to the transducer.
Try moving the transducer farther from the
liquid.
Obstructions under the transducer.
Check for obstructions on the front and sides
of the transducer.
Coating on the face of the transducer.
Clean the transducer face. If this is a constant
problem, try coating the face of the transducer
with a very thin film of silicone grease to keep
the debris from collecting.
The transducer resonates against steel
mounting rails.
Use the proper rubber isolation washers.
No Change in Level Readings or
Inaccurate Level Readings.
—
Check the logged data to see when this
started to occur. Go to the event log to see if
anything happened during the same time.
Calibration Re-calibrate the unit.
Bad transducer. Try a different transducer.