Omega FMA1700A User Manual page 23

INDICATION
No zero reading after 15
minute warm up time and
no flow condition.
No zero reading after 15
minute warm up time and
no flow condition. Display
reading does not response
on zero adjustment.
No zero reading after 15
minute warm up time and
no flow condition. Display
reading does not response
on zero adjustment. But
analog output 0-5 Vdc can
be adjusted from 10mV
up to 0.5 Vdc with zero
potentiometer R34.
LCD Display remains blank
when unit is powered up.
But flow can be observed
on analog output 0-5 Vdc
(pis 2 and 3 of the
D-connector).
LCD Display remains blank
when unit is powered up.
No response on the flow
from analog output
0-5 Vdc (voltage is less
than 15 mV).
LIKELY REASON
Embedded temperature
has been changed.
Power supply voltage is
less than 11.0 Vdc.
Wire is disconnected
inside of the LCD Display.
LCD Display connector is
not attached to the
FMA1700A/1800A or
connection is loose.
Wire is disconnected
inside of the LCD Display.
Power supply is bad or
polarity is reversed.
PC board is defective.
19
REMEDY
Readjust ZERO
potentiometer R34 through
the access hole
(see page 14 for details).
Measure voltage on pins 4
and 5 of the 9 pin
D-connector. If voltage is less
than 11.0Vdc replace power
supply with new one (regulat-
ed 12.0 Vdc, 250 mA mini-
mum is recommended).
Carefully remove the LCD
from FMA1700A/1800A.
Remove the aluminum
housing on the side of the
connection cable. Side the
LCD assembly out of the
aluminum housing. Check
connection for all four wires.
If any wire is disconnected
restore connection and read-
just zero potentiometer R34 to
get zero reading on the
display (ensure gas source is
disconnected and no
seepage or leak occurs in to
the meter).
Check LCD connector
(remove and reinstall LCD
connector)
See instructions for pos. 3
Measure voltage on pins 4
and 5 of the 9 pin
D-connector. If voltage is less
than 11.0Vdc replace power
supply with new one
(regulated 12.0 Vdc, 250 mA
minimum is recommended).
If polarity is reversed
(reading is negative) make
correct connection.
Return FMA1700A/1800A to
factory for repair.