239-0111

Access CC Voltage Diagnostics

Press MOD key > DIAGNOSIS > CC > select the CC module indicated in %2 parameter. Observe the 'DC Bus Voltage' real-time value. Nominal value should be 540-750V for 3x480V systems, 270-375V for 3x230V systems.

Record the voltage value during normal operation and during axis motion to identify dynamic voltage drops that only occur under load.

Check Power Supply Unit Output

Measure DC bus voltage directly at the PSU output terminals using a multimeter set to DC voltage range >800V. Compare with the CC module's reported value to verify measurement accuracy.

High voltage present. Use CAT III rated test equipment and appropriate PPE. Lock out main power before accessing terminals.

Verify Line Reactor and Pre-Charge

Check that the line reactor (if equipped) is properly connected and not shorted. Verify the DC bus pre-charge circuit completes before drive enable by observing the pre-charge contactor timing.

A failing pre-charge resistor or relay can cause insufficient initial voltage that drops further under load.

Review Simultaneous Axis Loading

Examine the NC program or PLC sequence for simultaneous high-acceleration moves on multiple axes. Check if alarm correlates with specific motion patterns using the Error Memory timestamp.

Modify MP1010 (axis-specific current limits) to reduce peak power demand if undersized power supply is confirmed.

Perform CC Module Swap Test

Power down the control. Document all cable connections to the suspect CC module. Swap the affected CC module with a CC from a different axis that is functioning normally. Power up and test both axes.

Ensure axes are mechanically secured before testing. Re-run CC auto-setup if encoder interfaces differ between swapped modules.

Check CC Error Memory for Detail

Navigate to MOD > DIAGNOSIS > CC > select module > Error Memory. Look for additional fault codes or voltage-specific subcodes that indicate which internal rail failed (e.g., +15V, -15V, +5V).

Error code detail bytes often indicate specific voltage rail. Note the %1 parameter which may encode the internal voltage identifier.

Inspect CC Module for Physical Damage

Remove the CC module and visually inspect for bulging electrolytic capacitors, burn marks, or component discoloration. Check cooling airflow path is unobstructed and heat sink is clean.

Failed electrolytic capacitors in the 24V supply section are common after 5+ years. Look for capacitor top venting or base leakage.

Replace CC Module

If swap test confirms module failure, replace with new or refurbished CC module. After installation, run CC auto-setup from MOD > System Configuration > CC Setup to configure encoder interface and commutation parameters.

Keep the failed module for depot repair service - Heidenhain often provides exchange credit for repairable modules.

Inspect DC Bus Bar Connections

Power down and lock out. Remove covers to access CC module DC bus connections at X401 (DC+) and X402 (DC-). Check for proper torque on terminal screws per installation manual (typically 1.2-1.5 Nm for M4 terminals).

Capacitors remain charged after power down. Wait minimum 5 minutes and verify <42VDC before touching bus bars.

Check for Terminal Discoloration

Examine the terminal screws, bus bars, and contact surfaces for any discoloration, oxidation, or heat marks indicating poor contact. Look for strand wire that has backed out of terminal blocks.

A single overheated terminal can affect voltage to multiple CC modules if they share the same bus bar segment. Check adjacent modules as well.