| LED Display | Alarm Description | Repair |
| A. | MDI connection failure | Check fiber optic cable connection between control and MDI/CRT unit. |
| Replace Master Board, MDI Pcb, or fiber optic cable, small power supply front panel. | ||
| C. | MDI Failure | Connection Unit for operators panel or connecting cable is defective. |
| F. | Connection Failure of connection unit or I/O cards D1 - D3 | Check fiber optic cable connections between these units. |
| Replace Master PCB, connection unit, I/O board, Fiber optic cable | ||
| Failed I/O module in I/O base unit. | ||
| H. | Connection Failure I/O | Connection Unit 2 or its connecting cable defective. |
| c. | Transfer error through fiber optic cable | Check Front Panel Power Supply, Replace Master PCB, MDI PCB, Connection Unit PCB, I/O Unit , Fiber Optic Cable |
| J. | PC or interface converter not functioning | Check PC-ROM cassette, PC RAM Board, or interface converter is mounted on Master PCB. |
| L. | Waiting for PC ready | Replace PC ROM, PC ROM Cassette or PC RAM Board. |
| b. | RAM check error | Replace Master PCB or ROM/RAM board |
| 8 | RAM Check | Check Power Supply, Clear Memory and Reload parameters. Replace Master Board. |
| d. | Power Supply Ready Signal | Replace Power Supply, Master PCB |
| E. | System Error | Replace Master PCB,Rom PCB or NC Software ROM |
| Wrong option parameters | ||
| No message on CRT- Clear memory | ||
| O. | IPL Mode | |
| 1 | Normal Operation | |
| 4 | Bad ACP | Replace ACP daughter board |