Omega FMA1700A User Manual page 24

INDICATION
LCD Display reading does
not correspond the correct
flow range according analog
output 0-5 Vdc signal.
LCD Display reading and
analog output 0-5Vdc
signal are fluctuate in wide
range during the flow
measurement.
LCD Display reading does
correspond the correct flow
range, but 0-5 Vdc output
signal does not change
(always the same reading
or around zero).
LCD Display reading and
0-5 Vdc output voltage do
correspond the correct flow
range, but 4-20 mA output
signal does not change
(always the same or
reading around 4.0 mA).
Calibration is off (no more
than 3.0 % F.S.).
LIKELY REASON
LCD Display is adjusted for
wrong flow range or
engineering units.
Output 0-5 Vdc signal (pins
2 and 3 of the D-connector)
is shorted on the GND or
overloaded.
Output 0-5Vdc schematic is
burned out or damaged.
External loop resistance is
open or more than 500
Ohm.
Output 4-20 mA schematic
is burned out or damaged.
FMA1700A/1800A has initial
zero shift.
20
REMEDY
Readjust LCD Display
scaling for required full scale
flow (see 7.4 on page 16).
Check external connections
to pins 2 and 3 of the
D-connector. Make sure the
load resistance is more
than 1000 Ohm.
Return FMA1700A/1800A to
factory for repair.
Check external connections
to pins 8 and 9 of the
D-connector. Make sure the
loop resistance is less than
500 Ohm.
Return FMA1700A/1800A to
factory for repair.
Shut off the flow of gas into
the FMA1700A/1800A
(ensure gas source is dis-
connected and no seepage
or leak occurs in to the
meter). Wait for 15 minute.
with no flow condition and
readjust zero potentiometer
R34 to get zero reading on
the display.