Dynasonics DDFXD Doppler Ultrasonic Flow Meter - Manual (Page 51)

06-DPP-UM-00147 02/12 51
TROUBLESHOOTING
Symptom Resolution
Display does not light up
1. Insufficient power to DFX monitor – measure voltage at J2
2. Power supply not properly wired to J2 – See Part 3
3. Fuse F1 is open or not installed
4. Power supply jumpers are not installed properly – See Part 3
5. Ribbon cable between the door and enclosure back is not fully en-
gaged into the two sockets
ERROR on the DFX Display
1. Transducers not properly coupled to the pipe – couplant not present
or pipe not properly prepared
2. Transducer not properly wired to the J4 Terminal block inside the DFX
– review the Wiring Diagram on the inside door of the DFX
3. More than one DFX installed on the piping system – See Part 3: Mul-
tiple Unit Installation
4. Insufficient particles over 35 microns – inject air upstream of the
transducers
5. Too many particles that are smaller than 35 micron – ultrasonic me-
ters likely will not operate
6. Transducer failure – unplug transducer cable from J4, measure capac-
itance between blue/clear or red/black Receive and Transmit. Verify
that the capacitance on each set is approximately 2 nF (nano Farads)
– and within 0.02 nF of each other
Unstable Flow Reading
1. Relocate transducer to a pipe position with less hydraulic disturbance
2. Increase Damping value
3. Ensure that ground connection is properly connected to meters
earth ground. See Figure 3.2
Inaccurate Flow Reading
1. Verify that pipe ID is entered correctly
2. Verify that an erroneous Scale Factor has not been entered
3. Verify that erroneous Linearization values have not been entered
4. Verify that AGC is set to Normal
5. Verify that the transducers are mounted square and 180 degrees
apart on the pipe
6. Relocate transducer to a pipe position with greater straight run
length
7. DP7 Probe not aligned in the pipe
Analog output does not
match data collection
system
1. Verify 4-20 mA calibration
2. Verify 4 mA and 20 mA flow settings
3. Verify that the loop load is within the supply voltage range
4. Run 4-20mA TEST feature – verify that mA outputs coincide with
expected data collection system readings