Digital Controls

Cause

Failed Opto isolator.

Solution

Return control to factory for repair.

Cause

Transistor failure.

Solution

Return control to factory for repair.

Cause

Failed electrolytic capacitor.

Solution

Return control to factory for repair.

Cause

Mode switch failed in open position.

Solution

Return control to factory for repair.

Cause

Corrosion byproducts on relay contacts.

Solution

Clean relay contacts. Do not operate control without rear cover.

Cause

Failed capacitor not filtering power supply.

Solution

Return control to factory for repair.

Cause

Relay damaged due to electrical arc/over current

Solution

Return control to factory for repair.

Cause

Defective relay.

Solution

Return control to factory for repair.

Cause

Excessive current through relay contacts.

Solution

Check installation for source of excessive current. Add auxiliary relay as required. Return control to factory for repair.

Cause

Solder bridge on relay input.

Solution

Remove solder bridge.

Cause

Control inadvertently placed in calibration mode while checking set point.

Solution

Recalibrate control per instructions.

Cause

Control enters calibration mode due to pressure against all three-mode keys.

Solution

Remove rear cover, realign circuit board and reattach cover. Recalibrate control per instructions.

Cause

Corrosion on components.

Solution

Scrap/replace control. Do not operate control without rear cover.

Cause

No output voltage from step-down transformer (combination type controls).

Solution

Test secondary side of transformer for appropriate output voltage and replace if required.

Cause

Thermal protector from heater open or not connected into control circuit. Warning: Do not operate heaters without thermal protection.

Solution

Making sure all power is off, verify thermal protector continuity with an ohm or continuity meter, replace as required and connect across terminal blocks as directed in wiring diagram.

Cause

Open coil on relay (combination type controls).

Solution

Test relay by applying rated voltage to coil. Replace if defective.

Cause

Incorrect transformer or relay coil used.

Solution

Check voltage ratings of components to make sure they match rating of secondary circuit. Replace as required.

Cause

No output voltage from step-down transformer (combination type controls).

Solution

Test secondary side of transformer for appropriate output voltage and replace if required.

Cause

Corrosion on contacts of relay.

Solution

Return control to factory for possible repair/relay replacement.

Cause

Excessive current through relay contacts.

Solution

Check system for cause of excessive current. Add auxiliary relay as required. Return control to factory for repair.

Cause

Control has never been calibrated or configured and is using default values.

Solution

Reset configuration and calibration values as noted in the manual (see appropriate manual for directions).

Cause

Control not calibrated or calibration/setup information corrupted. Control is operating on preset default values.

Solution

Reset calibration and input settings as listed in control manual (see appropriate manual for directions).

Cause

Control configuration values set for two wire RTD sensor but calibration parameters not changed from default values.

Solution

Reset configuration to match sensor (see appropriate manual for directions).

Cause

Sensor value of RTD out of range low (resistance value less than –40F/40C measured). Shorted sensor, connections or sensor leads.

Solution

Remove RTD sensor, inspect for damage to lead wires and connection. Test with ohmmeter to verify integrity (approximately 1007 ohms at 72F/22C). Repair/replace and reconnect as required.

Cause

Failed IC.

Solution

Return control to factory for repair.

Cause

Control sensor parameter set for RTD while being operated with a thermocouple.

Solution

Reset sensor parameter for sensor being used..

Cause

Failed capacitor loading down temperature input.

Solution

Return control to factory for repair.