3600 Analyzer for O
2
Measurement—Operator’s Manual 33
3600O2.OM.E9903
1.5.10 Troubleshooting
Orbisphere analyzers are fully factory tested before shipment. Provided they have
been handled properly and are correctly installed, they should be trouble-free.
Here is a list of possible troubles caused by poor handling or identifiable
installation conditions. If you cannot find a solution here, contact your authorized
Orbisphere service technician.
Problem Probable Cause Possible Solution
Sensor won’t
calibrate, even after
thorough servicing
Repeated calibrations
go beyond “expected
limits” of instrument
Re-select membrane from
“Options/Membrane” menu, section 1.4.11.
Then, recalibrate the sensor.
Instrument’s internal
barometric pressure
sensor needs calibration
Recalibrate using “Calibrate/Barom.
Pressure” menu, section 1.3.3.1. Check
against reliable barometer. Do not correct for
sea level!
H
2
S insensitivity option
unnecessarily enabled
Unless you need “H
2
S insensitive” (which
uses different electrolyte) disable from
“Options/Gas” menu, section 1.4.10.
No analog output
signal (portable
instrument)
Portable instrument
requires mains power
for analog output
Connect to appropriate mains power.
“0000” O
2
levels
displayed
“XXXX” selected for
unit lowest range
Choose “X.XXX, XX.XX or XXX.X” from
“Options/Display Units” menu, section 1.4.1.
Shorter-than-expected
sensor operation (in
relatively high DO
2
)
High O
2
concentrations
require more work from
electrochemical sensor
Shut off analyzer when not needed.
Unexpected/incorrect
DO
2
readings
Sample air leak Set flow rate to 100 ml/min; wait until stable.
Slowly increase to 200 ml/min.
If a significant DO
2
decrease is displayed, a
sample air leak is likely.
High residual current Place sensor in dearated sample; wait for low
reading; check concentration against low
measurement limit (see tables in section 3).
If concentration is significantly higher than
low limit, try a sensor service, section 1.5.1.
Instrument and
“moca3600” PC
program are
operational, but do
not work together
(i.e. no data transfer)
Improper PC-to-
instrument connection
Confirm that:
• “Options/Serial Output” is Enabled, section
1.4.5;
• All 9 pins are available, if using a 25-to-9
pin converter at the PC;
• There are no PC COM port/IRQ conflicts.
Alarm relays won’t
operate properly
Normally open /
normally closed state
reversed
Both NO and NC outputs available; confirm
wiring to LEMO (portable instrument) or
terminal block (process instrument)
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