Instruction Manual
Alpha DO 500
37
8. Troubleshooting
Problem
Cause
Solution
Power on, but no
display
a) Loose connections
b) Power cables not in
correct polarity (+ & -)
c) Incorrect output voltage
of the power supply
a) Ensure cables make good
contact
b) Re-wire loop cables with
correct polarity
c) Use a power supply with
specified output voltage
Unstable dissolved
oxygen reading
a) Air bubbles in electrode
b) Dirty electrode
a) Tap electrode to remove air
bubbles
b) Clean electrode and
recalibrate
Oscillating
temperature readings
a) Electrical noise
interference
a) Ensure shield wire is
properly connected to pin 7
Slow response
a) Dirty / Oily electrode
a) Clean electrode
Blinking ATC
a) No temperature probe
connection during ATC
mode
a) Ensure temperature
sensing cable makes good
contact
Blinking electrode
annunciator
a) Error in calibration
a) Ensure calibration standard
solution is not
contaminated. Ensure
electrode is clean.
Or (Dissolved
oxygen)
a) Dissolved oxygen
electrode is not
connected
a) Ensure electrode makes
good contact with
Transmitter
Or (Temperature)
a) Temperature probe is
not connected when
ATC enabled
a) Ensure electrode makes
good contact with
Transmitter