NC Machine electrical system fault investigation, analysis and diagnosis process is the fault of the excluded, once identified, would almost equal fault ruled out. Therefore fault analysis and diagnosis methods will become essential. Fully commonly used diagnostic method is as follows:
(1) visual inspection of this is the beginning of fault analysis method must be used, is to use the sensory examination.

① asked officers to the scene fault asked in detail about the process of failure, failure symptoms and the consequences of failure, and the whole process of analysis and judgment may be asked repeatedly.

② overall visual look of the machine part of the work in a normal state of the state (such as the location coordinates axis spindle state of the knife, manipulator position), the electronic control devices (such as the NC system, temperature control device, lubrication equipment, etc.) whether the police instructions, local checked for insurance Duan burned, charred components, cracking, shedding wires and cables, the location of the correct operation of components or otherwise, and so on.

③ touch in the whole power conditions can touch the main circuit boards in the installation, plug Block Plug status, power and signal wires (such as servo motor contactor and wiring) connected to discover the state of the reasons for the problems which may occur.

④ energized this means to check for smoke Arc, whether abnormal sound, smell and touch the motor overheating and whether the presence of electronic components, once the immediate power analysis found.

(2) the use of conventional test equipment electrical instruments, the group of TAC, DC supply voltage, DC and related measurements such as pulse signal, which may find fault. For example, multimeter check the power supply, and set up some boards signal state measurement points of measurement associated with the pulse of oscilloscope signal amplitude, phase or even whether, PLC programming of the PLC program find fault location and causes.

(3) signals and warning instructions analysis

① hardware alarm instructions This means including NC system, servo systems, the electronic, electrical installations on the various state and fault indicator light beacons state and the corresponding function will be informed of the contents and instructions cause of the malfunction and exclusion method.

② software alarm system software instructions As mentioned above, the PLC program and the processing procedures are usually the fault alarm, the alarm that the basis of the corresponding control of the manual will be informed of the possible cause of the malfunction and troubleshooting methods.

(4) interface state examination of modern CNC system will be more integrated in which PLC, CNC and PLC interface signal with a series of mutual communication link. Some fault with the signal interface errors or loss related to these interfaces can be some signal in the corresponding interface boards and input / output boards that are light, some simple operation can be displayed on the CRT screen, and all the signals can interface with PLC programming for redeployment. Such inspection methods require maintenance staff should not only familiar with the machine interface signals, but also familiar with the programming of the PLC application.

(5) Adjustment Act of CNC system, PLC and servo drive systems are provided with many parameters can be modified to suit different machine, different state requirements. These parameters can not only with the electrical system to match specific machine, but the machine is the best of all the functions needed. Therefore, any changes in parameters (especially the analog parameters) are not allowed even lost; The random bed caused by the long-term operation of the mechanical or electrical properties of the first to break the state and best match of the state. Such multi-fault classification refers to a fault in the latter category failure, the need to realign related to one or more parameters may exclude. This approach demands the maintenance staff is very high, not only for a very specific understanding of system parameters, we know their addresses familiar with its role, but a more extensive electrical debugging experience.

(6) Spare parts replacement of the fault analysis focused on a printed circuit board, the integrated circuit and to the continuing expansion of its failure to implement on a regional and even a certain element is very difficult, in order to reduce downtime in the same spare parts under the condition can first put on spare parts , and then gave fault repair inspection plate. Spare parts replacement to the board to the following questions.

① any replacement parts must be conducted in power.

② many printed circuit boards are some short rod or switch settings to match the actual needs, the replacement of spare parts under the board must record the original location and setting switch state, and new plates for the same set, otherwise they will be unable to work and produce alarm.

③ some of the printed circuit board replacement to be replaced after certain completion of the software to operate with the parameters established. This requires careful reading of the corresponding circuit board use.

④ Some printed circuit board is not easily drawn, for example, work with the board memory, or spare battery plates, it would lose useful parameters or procedures. Also to be replaced to comply with the instructions. In light of the above conditions, pull out the old board replacement before the new board will have to carefully read the relevant information, understand requirements and steps after getting to work to avoid creating greater fault.

(7) Cross-transposition of the board found fault determine whether or not fault plate without spare parts circumstances, the system of the same or compatible board swap two checks, for example, two coordinates the directive board or plate servo fault judgment from the exchange board or fault location. The cross-transposition law should pay particular attention to not only the correct wiring hardware exchange, but also will be a series of the corresponding parameters exchanged, or a failure, it actually will create new thinking fault caused the confusion, we must advance thoughtful, well designed software and hardware exchange programs, accurate further inspection exchange.

(8) special treatment by the current NC system has entered the PC-based, open, the development phase, which increasingly rich content software, system software, machine tool maker software, and even its own software users, due to a software logic in the design of some of the inevitable problems, Some fault state would make no analysis, for example, Vista phenomenon. Such malfunctions can take special means to deal with, such as power unit, a pause after the boot is sometimes possible to eliminate fault. Maintenance personnel can be in their long-term practice of its exploration or other effective means.