Troubleshooting

_{Source: Intuition-6 Instruction Manual Rev. H, Pages: 103–110} This section covers common issues and their solutions. For problems not covered here, contact technical support with the controller model, software version, and alarm history.

Calibration Failures

Use these symptom tables to diagnose calibration errors by sensor type.

Contacting Conductivity Sensors

Symptom	Possible Cause	Solution
Cal fails, reading too low	Electrode fouled	Clean electrode surfaces
Cal fails, reading erratic	Air bubbles on electrode	Ensure electrode fully immersed
Cal fails, no change with standard	Cable damaged	Check cable continuity
Reading drifts after cal	Temperature compensation wrong	Verify temp sensor, check comp factor
Reading always zero	Electrode disconnected	Check wiring connections

Electrodeless Conductivity Sensors

Symptom	Possible Cause	Solution
Installation factor < 0.5	Sensor coated or too close to metal	Clean sensor, maintain 6” clearance
Installation factor > 1.5	Air or non-conductive material near sensor	Ensure sensor fully immersed
Reading unstable	Stray electrical currents	Move sensor away from grounding points
Cal fails	Wrong range selected	Select range matching process conductivity

pH Sensors

Symptom	Possible Cause	Solution
Slope < 48 mV/pH	Electrode worn or contaminated	Clean electrode; replace if still low
Slope > 62 mV/pH	Contaminated buffer or wrong buffer	Use fresh buffer, verify buffer value
Cal fails at second buffer	Reference junction fouled	Soak in KCl solution; replace if persistent
Slow response	Coated glass bulb	Clean with HCl or pepsin solution
Reading won’t stabilize	Temperature compensation issue	Check temp sensor connection
Always reads 7.0	Broken glass bulb or open circuit	Inspect electrode; replace if damaged

ORP Sensors

Symptom	Possible Cause	Solution
Reading won’t stabilize	Platinum surface contaminated	Polish with alumina; clean electrode
Reading far from expected	Reference junction fouled	Clean or replace electrode
Cal offset > ±100 mV	Electrode failing	Replace electrode

Disinfection Sensors

Symptom	Possible Cause	Solution
Cal fails, reading low	Membrane damaged or fouled	Replace membrane cap
Reading erratic	Air bubbles in flow cell	Check flow, bleed air from system
Reading always zero	No sample flow	Verify flow, check inlet restriction
Cal offset way off	Electrolyte exhausted	Replace membrane cap with electrolyte

Analog Inputs (4-20 mA)

Symptom	Possible Cause	Solution
Cal fails, offset > 2 mA	Wiring error	Verify wiring per transmitter type
Reading stuck at 0 mA	Transmitter not powered	Check 24V supply, wiring
Reading stuck at 21+ mA	Transmitter output saturated	Check transmitter input range
Reading noisy	Electrical interference	Use shielded cable, separate from AC

Temperature Sensors

Symptom	Possible Cause	Solution
Reading far off	Wrong sensor type selected	Verify RTD/thermistor type in settings
Open circuit alarm	Cable break	Check continuity, repair cable
Reading drifts	Moisture in cable	Replace cable; seal connections

Alarm Messages

Reference these tables for alarm meanings and recommended actions.

Sensor Alarms

Alarm	Meaning	Action
Hi/Hi Alarm	Value exceeds high-high limit	Check process; may indicate control failure
High Alarm	Value exceeds high limit	Monitor, may require adjustment
Low Alarm	Value below low limit	Check process; chemical may be exhausted
Lo/Lo Alarm	Value below low-low limit	Urgent: check sensor and process
Range Error	Reading outside sensor capability	Check sensor installation, calibration
Cal Required	Days since calibration exceeded	Calibrate sensor

Output Alarms

Alarm	Meaning	Action
Output Timeout	Relay on longer than Output Time Limit	Check process; reset timeout when resolved
Daily Max Timeout	Accumulated time exceeded daily limit	Clears at midnight; check for runaway condition
Event Skipped	Timer event missed due to overlap or interlock	Check interlocks; review timer schedule
Flow Verify	Feed monitor saw no pulses while pump running	Check pump, tubing, feed monitor

System Alarms

Alarm	Meaning	Action
Power Fail	Controller lost power and recovered	Check for brownouts; verify clock accuracy
Network Error	Ethernet communication failed	Check cable, IP settings
Email Fail	Unable to send email	Check SMTP settings, network access
Modbus Error	Communication with remote device failed	Check wiring, slave address settings

Control Issues

Use these checks when outputs do not behave as expected.

Relay Won’t Turn On

Check HOA State — Must be in Auto for automatic control

Check Set Point — Process value must exceed set point (force lower) or be below (force higher)

Check Interlocks — Any interlocked input will prevent activation

Check Output Timeout — May need to reset after previous timeout

Relay Won’t Turn Off

Check HOA State — If in Hand, relay stays on until time limit or manual change

Check Deadband — Value may still be in control range

Check Off Delay — Relay may be in off delay period

Check Activate With — Another channel may be holding relay on

Poor Control (Overshooting/Undershooting)

For On/Off Control:

Increase deadband to reduce hunting
Add off delay to prevent rapid cycling
Add on delay if chemical reaction is slow
Enable duty cycling for slow-responding systems

For Proportional/PID Control:

Reduce gain for less aggressive response
Increase integral time for slower integration
Reduce proportional band for faster response (may increase overshoot)
Verify sensor is in representative location

Flow Timer Not Triggering

Verify flow meter is receiving pulses (check digital input status)

Check Volume/Contact setting matches flow meter specifications

Verify K-factor is correct for paddlewheel meters

Check for wiring issues (contact closure vs. hall effect)

Biocide Timer Not Running

Verify current day/time is correct in controller

Check event schedule matches intended days

Verify interlocks are not blocking execution

Check Add Last Missed setting if events seem skipped

Diagnostic Lights

The controller has diagnostic LEDs visible when the front panel is open:

LED	Color/State	Meaning
Power	Green steady	Power supply OK
Run	Green blinking	Processor running normally
Ethernet	Green/Amber	Network activity
Relay LEDs	Green when active	Relay energized

LEDs are only visible with front panel open. Do not operate controller with panel open while powered.

Communication Troubleshooting

Follow these network and protocol checks for connectivity issues.

Ethernet Not Connecting

Verify cable is connected and linked (LED on)

Check IP settings (DHCP or static)

Ping controller IP from computer

Verify subnet mask matches network

Check gateway if accessing from different subnet

Web Pages Won’t Load

Verify browser is accessing correct IP address

Try different browser or clear cache

Check password (default shown on label)

Verify Ethernet settings haven’t changed

Email Not Sending

Verify network connectivity

Check SMTP server address and port

Verify authentication credentials

Check firewall/security settings

Test with simpler mail server if possible

Modbus Communication Fails

Verify slave address settings

Check baud rate and parity match

Verify register addresses

Use Modbus polling tool to test

Check wiring for RS-485 connections

Sensor-Specific Issues

Use these fixes for common sensor behavior changes.

pH Reading Drifts Between Calibrations

Increase calibration frequency
Check for process contamination
Verify proper sensor installation (U-trap, immersion)
Consider replacing electrode if slope is declining

Conductivity Reading Fluctuates

Check for air bubbles in sample line
Increase smoothing factor in settings
Verify temperature compensation settings
Check for stray electrical currents (electrodeless)

Disinfection Reading Drops to Zero

Verify sample flow through sensor
Check for membrane tear or fouling
Confirm membrane cap has adequate electrolyte
Ensure no back pressure on flow cell outlet

ORP Reading Unstable After Cleaning

ORP electrodes need time to stabilize
Immerse in process water for 30+ minutes
Consider that ORP inherently varies more than other measurements

When to Contact Support

Contact Walchem technical support if:

Calibration failures persist after electrode replacement
Controller displays error codes not in this manual
Repeated fuse failures occur
Display is blank or corrupted
Controller restarts unexpectedly
Control behavior is erratic despite correct programming

Information to have ready:

Controller model number (on label)
Software version (Configuration → Global Settings)
Complete alarm history
Description of symptoms and when they started
Recent changes to system or settings

Sources

Intuition-6 Instruction Manual Rev. H

Pages 103–110 • February 2024

Get Started

Product Support

Troubleshooting

Troubleshooting

Calibration Failures

Contacting Conductivity Sensors

Electrodeless Conductivity Sensors

pH Sensors

ORP Sensors

Disinfection Sensors

Analog Inputs (4-20 mA)

Temperature Sensors

Alarm Messages

Sensor Alarms

Output Alarms

System Alarms

Control Issues

Relay Won’t Turn On

Relay Won’t Turn Off

Poor Control (Overshooting/Undershooting)

Flow Timer Not Triggering

Biocide Timer Not Running

Diagnostic Lights

Communication Troubleshooting

Ethernet Not Connecting

Web Pages Won’t Load

Email Not Sending

Modbus Communication Fails

Sensor-Specific Issues

pH Reading Drifts Between Calibrations

Conductivity Reading Fluctuates

Disinfection Reading Drops to Zero

ORP Reading Unstable After Cleaning

When to Contact Support

Sources

Intuition-6 Instruction Manual Rev. H

​Troubleshooting

​Calibration Failures

​Contacting Conductivity Sensors

​Electrodeless Conductivity Sensors

​pH Sensors

​ORP Sensors

​Disinfection Sensors

​Analog Inputs (4-20 mA)

​Temperature Sensors

​Alarm Messages

​Sensor Alarms

​Output Alarms

​System Alarms

​Control Issues

​Relay Won’t Turn On

​Relay Won’t Turn Off

​Poor Control (Overshooting/Undershooting)

​Flow Timer Not Triggering

​Biocide Timer Not Running

​Diagnostic Lights

​Communication Troubleshooting

​Ethernet Not Connecting

​Web Pages Won’t Load

​Email Not Sending

​Modbus Communication Fails

​Sensor-Specific Issues

​pH Reading Drifts Between Calibrations

​Conductivity Reading Fluctuates

​Disinfection Reading Drops to Zero

​ORP Reading Unstable After Cleaning

​When to Contact Support

​Sources

Intuition-6 Instruction Manual Rev. H

Troubleshooting

Calibration Failures

Contacting Conductivity Sensors

Electrodeless Conductivity Sensors

pH Sensors

ORP Sensors

Disinfection Sensors

Analog Inputs (4-20 mA)

Temperature Sensors

Alarm Messages

Sensor Alarms

Output Alarms

System Alarms

Control Issues

Relay Won’t Turn On

Relay Won’t Turn Off

Poor Control (Overshooting/Undershooting)

Flow Timer Not Triggering

Biocide Timer Not Running

Diagnostic Lights

Communication Troubleshooting

Ethernet Not Connecting

Web Pages Won’t Load

Email Not Sending

Modbus Communication Fails

Sensor-Specific Issues

pH Reading Drifts Between Calibrations

Conductivity Reading Fluctuates

Disinfection Reading Drops to Zero

ORP Reading Unstable After Cleaning

When to Contact Support

Sources