Code 231-B900: CC%2 supply voltage %1
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical CC%2 supply voltage %1 alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
[Cause of error] - The supply voltage Vcc(x) was out of range. - +4 = undervoltage Vcc(+5 V) The load from external components (e.g. encoders) is too large. - +6 = overvoltage Vcc(+5 V) The power supply unit is defective. - +14 = undervoltage Vcc(+15 V) The power supply unit is defective. - +16 = overvoltage Vcc(+15 V) The power supply unit is defective. - -14 = undervoltage Vcc(-15 V) The power supply unit is defective. - -16 = overvoltage Vcc(-15 V) The power supply unit is defective. [Error correction] - Inform your service agency. - Measure the supply voltage Vcc(x). - Vcc(+5 V) < +4.75 V Check the encoder connections. - Vcc(+5 V) > +5.50 V Exchange the power supply unit. - Vcc(+15 V) < +14.25 V Exchange the power supply unit. - Vcc(+15 V) > +16.50 V Exchange the power supply unit. - Vcc(-15 V) < -14.25 V Exchange the power supply unit. - Vcc(-15 V) > -16.50 V Exchange the power supply unit.
Source: HEIDENHAIN NC Error Messages — TNC7/640/620/320/128, CNC PILOT 640, MANUALplus 620 (10/2023)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Heidenhain TNC Series CNC Alarms
Heidenhain controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 231-B900 on the TNC Series CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Heidenhain's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 4497 Heidenhain TNC Series CNC codes.
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