| 51 | PCB in fault. | Internal fault of the control board (MC12FN5) or its power supplies; the control unit detects an anomaly in the PCB. Check 230 VAC at M16 L/N, 5 VDC at M9.1–M9.2, and fuses F1/F2; if correct and the issue persists, replace the board. |
| 52 | PCB in fault. | Anomaly diagnosed in the control board; possible parameter corruption or micro/EEPROM fault. Check voltages (230 VAC and 5 VDC), fuses F1/F2, and wiring; if everything is correct, replace the board. |
| 53 | PCB in fault. | Diagnosis of control board fault; it may be due to absence of 5 VDC or malfunction of the logic. Check 230 VAC at the input, 5 VDC on the PCB, and fuses F1/F2; if correct and the error persists, replace. |
| 54 | PCB in fault. | Internal fault detected by the PCB itself (safety/management control). Measure 5 VDC logic, check fuses F1/F2 and continuity of harnesses; if values are OK and fault persists, replace the PCB. |
| 55 | PCB in fault. | Unit management error (PCB) or its internal power supplies/regulations. Check for presence of 230 VAC and 5 VDC, fuses F1/F2, and connections; if everything is correct, replace the PCB. |
| 56 | PCB in fault. | Alarm associated with the control board due to hardware or control defects. Check 5 VDC at M9.1–M9.2, fuses F1/F2, and connector continuity; if OK, replace the PCB. |
| 57 | PCB in fault. | Fault diagnosis on the control/safety PCB. Confirm power supplies (230 VAC, 5 VDC), check fuses F1/F2 and harnesses; if everything is correct, replace the PCB. |
| 58 | PCB in fault. | Internal fault of the control board (logic/parameterization). Measure 5 VDC of logic, check fuses F1/F2 and cables; if the voltages are present and the error persists, replace the PCB. |
| 59 | PCB in fault. | Anomaly in the control board; the electronics enter a fault. Check 230 VAC and 5 VDC and fuses F1/F2; if correct and there is no communication/start-up, replace the PCB. |
