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Check CompactFlash card status

Access MOD function → System Info → Storage Devices to verify CompactFlash card is detected and shows available space.

Look for 'Read Only' status or error indicators next to the CF card entry

Verify write protection

Power down control, remove CompactFlash card, and check physical write-protect switch is in unlocked position.

Always power down completely before removing storage media

Test card integrity

Insert card in PC and run CHKDSK /F to check for file system errors and bad sectors.

Backup TNC partition before running disk repair utilities

Replace if necessary

If card shows errors or bad sectors, replace with Heidenhain-approved CompactFlash card and restore from backup.

Use only industrial-grade CF cards rated for continuous operation

Check system partition space

Navigate to MOD → System Info → Storage Devices and verify free space on system partition (typically partition 1).

System partition should maintain at least 10% free space for optimal operation

Clear temporary files

Access MOD → Data Management → System Files and delete old log files, temporary files, and unused backup files.

Do not delete system configuration files or active program data

Archive old programs

Move older NC programs and setup sheets to external storage or secondary partitions using File Manager.

Use TNC's built-in compression when archiving to save additional space

Verify write capability

Attempt to save a small test file to confirm write operations are now functional.

Create a simple .txt file in the TNC directory to test write permissions

Access machine parameters

Enter MOD mode → Machine Parameters and attempt to view current parameter settings, noting any error messages.

Look for parameters showing default values instead of machine-specific settings

Backup current parameters

Use MOD → Data Backup → Machine Parameters to create backup file before attempting repairs.

Always backup parameters before making changes - incorrect parameters can damage machine

Restore from backup

Load known good machine parameter backup using MOD → Data Management → Restore Machine Parameters.

Use the most recent backup that was created during normal operation

Reinitialize if necessary

If no backup available, perform controlled restart with parameter initialization via MOD → System → Initialize Parameters.

Parameter initialization requires complete machine recalibration and setup

Run memory diagnostics

Access MOD → Diagnosis → Hardware Tests → Memory Test to check RAM and NVRAM integrity.

Run extended memory test during machine downtime for comprehensive check

Check system event log

Review MOD → Diagnosis → Event Log for memory-related errors or hardware fault messages.

Look for recurring patterns of memory errors that indicate failing hardware

Verify power supply stability

Check +5V and +3.3V supply voltages at control unit using multimeter during operation.

Measure voltages with control powered - use proper safety procedures

Contact Heidenhain service

If memory tests fail, document error codes and contact authorized service for control unit repair or replacement.

Have control serial number and software version ready when calling service

Disconnect external networks

Temporarily disconnect Ethernet and any external communication cables to isolate internal communication.

Test configuration write after each cable disconnection to identify problematic connection

Check internal bus status

Access MOD → Diagnosis → Communication → Bus Status to verify internal component communication.

All internal components should show 'Active' or 'OK' status

Reset communication modules

Perform controlled restart of communication subsystem via MOD → System → Reset Communication.

This will temporarily interrupt all network connections

Reconnect and test

Gradually reconnect external communications and test configuration write capability after each connection.

Add network connections one at a time to identify problematic devices