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.
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
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
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
