YSI Pro20 - Manual (Page 37)

T R O U B L E S H O O T I N G
ERROR MESSAGES
Symptom Possible Solution
Instrument will not calibrate;
instrument displays “Calibration
Over”, “Calibration Under”, or
“Unstable Reading” during
calibration. 1) Verify barometer reading
2) Verify correct sensor and membrane
type selection in the System Setup
menu.
3) Calibration sleeve may not be 100%
water saturated, ensure sponge is
moisten
4) Ensure adequate sample movement if
performing mg/L or ppm calibration
5) Allow sufficient stabilization time for
dissolved oxygen and temperature
AND wait at least 3 seconds before
confirming a DO % or DO %Local
calibration
6) Replace membrane and electrolyte
7) Clean sensor electrodes
8) Return system for service
Instrument will not turn on, a
battery symbol appears, or
“Critical Shutdown” displays on the
screen.
1) Low battery voltage, replace batteries
2) Batteries installed incorrectly, check
battery polarity
3) Return system for service
Barometer reads over/under,
Dissolved Oxygen and
Temperature display Over/Undr,
and pressing Cal key results in a
Barometric Pressure Over/Undr
message.
1) Barometer failure, return system for
service
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