Troubleshooting – YSI 55 User Manual
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12
7. Troubleshooting
NOTE: An error displayed briefly during the first few seconds after turning the
instrument on does NOT indicate a problem.
SYMPTOM
POSSIBLE
CAUSE
ACTION
1. Instrument will not turn on
A. Low battery voltage
B. Batteries installed incorrectly
C. Meter requires service
A. Replace batteries (Page 3)
B. Check battery polarity. (Page 3)
C. Return system for service (Page 14)
2. Instrument will not calibrate
A. Membrane is fouled or damaged
B. Probe anode is fouled or dark
C. Probe cathode is tarnished
D. System requires service
A. Replace membrane and KCl (Page 6)
D. Return system for service (Page 14)
3. Instrument "locks up"
A. Instrument has received a shock
B. Batteries are low or damaged
C. System requires service
A. Remove battery lid, wait 15 seconds
for reset, replace lid. (Page 3)
B. Replace batteries (Page 3)
C. Return system for service (Page 14)
4. Instrument readings are inaccurate
A. Cal altitude is incorrect
B. Salinity setting is incorrect
C. Probe not in 100% water saturated
air during Cal procedure
D. Membrane fouled or damaged
E. Probe anode is fouled or dark
F. Probe cathode is tarnished
G. System requires service
A. Recalibrate w/correct value (Page 8)
B. Recalibrate w/correct value (Page 8)
C. Moisten sponge and place in Cal
chamber w/ probe and Recal (Page 4,
8)
D. Replace membrane (Page 6)
G. Return system for service (Page 14)
5. LCD displays "LO BAT"
or
Main display flashes “OFF”
A. Batteries are low or damaged
A. Replace batteries (Page 3)
6. Main display reads “undr”
A. Probe current too low to calibrate
B. System requires service
A. Replace membrane and KCl (Page 6)
D. Return system for service (Page 14)
7. Main display reads “OVEr”
A. Sample O
2
concentration is more
than 20 mg/L
B. Probe current too high to calibrate
C. System requires service
A. Recalibrate using correct altitude and
salinity compensation (Page 8).
B. Replace membrane and KCl (Page 6)
E. Return system for service (Page 14)
8. Main display reads "Er 0"
A. Calibration current out of range
B. Instrument's self-test detects
improper probe voltage during
calibration
A. Replace membrane and KCl (Page 6)