239-0193

Check Main 24V Supply

Navigate to MOD > Service > Diagnosis > Voltage Monitor and verify 24V DC supply shows stable voltage between 22-26V DC.

Use a quality DMM to verify actual voltage at X101 terminals matches TNC display

Inspect Power Supply Unit

Check PSU LED indicators and measure ripple voltage - should be <100mV peak-to-peak on 24V rail.

Disconnect power before checking connections to avoid electrical hazards

Verify Load Distribution

Check if excessive current draw from drives or I/O modules is causing voltage sag during operation cycles.

Monitor voltage during axis movements to identify load-related drops

Test Under Load Conditions

Run diagnostic program with all axes moving while monitoring voltage stability in real-time diagnostics.

Use PLC program OEM cycle to simulate full machine load conditions

Perform FS Self-Test

Navigate to MOD > Service > FS Diagnosis and execute complete functional safety self-test sequence.

Document all sub-test results as Heidenhain service will require this data

Check FS Module Status

In MOD > Service > Hardware Info, verify FS module firmware version and hardware revision numbers.

FS module replacement requires factory recertification and safety parameter reload

Reset FS Parameters

Attempt FS parameter reset via MOD > Service > FS Diagnosis > Reset FS Controller if self-test shows parameter corruption.

Backup all safety parameters before reset using TNCopt or TNCremo

Verify Safety Chain Integrity

Test all safety inputs and emergency stop circuits to ensure FS monitoring circuits receive proper signal levels.

Never bypass safety circuits during testing - use proper test procedures only

Inspect Main Power Connections

Check all connections at X101 main connector and verify torque specifications per Heidenhain installation manual.

Power down completely and verify zero energy state before connection inspection

Test Cable Continuity

Use multimeter to verify continuity and resistance of all 24V supply cables from PSU to TNC control.

Resistance should be <0.1 ohms for proper power distribution

Check Ground Connections

Verify PE ground connections are tight and measure ground resistance - should be <0.1 ohms to cabinet ground.

Poor grounding can cause voltage reference issues affecting FS monitoring

Inspect for Environmental Damage

Look for signs of moisture, corrosion, or contamination on connectors and terminal blocks.

Clean connections only with approved contact cleaners and ensure complete drying

Check Cable Routing

Verify power and signal cables are properly separated and routed according to Heidenhain EMC guidelines in installation manual.

Maintain minimum 10cm separation between power and encoder cables

Inspect Shielding Integrity

Check all encoder and communication cable shields are properly terminated at both ends with 360-degree clamps.

Never cut or strip cable shields - use proper EMC cable glands only

Test with Drives Disabled

Temporarily disable servo drives and test if alarm persists to isolate drive-related EMI sources.

Use MOD > Service > Drive Diagnosis to selectively disable individual axes

Add EMI Filtering

Install additional ferrite cores on power cables or upgrade to higher-grade shielded cables if interference confirmed.

Use Heidenhain-approved cable types only to maintain EMC compliance