Aalborg GFM - Manual (Page 22)

18
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).
REMEDY
Readjust ZERO
potentiometer R34 through
the access hole
(see page 13 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
(regulated 12.0 Vdc, 250 mA
minimum is recommended).
Carefully remove the LCD
from GFM. Remove the alu-
minum 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 GFM to factory
for repair.
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 GFM or
connection is loose.
Wire is disconnected inside
of the LCD Display.
Power supply is bad or
polarity is reversed.
PC board is defective.