Troubleshooting of memory of high pressure injection molding machine
The fault phenomenon is: “module I is not online”.
Fault cause: the control system of the machine has multiple functional modules, and the system itself has strong self diagnosis function. The maintenance personnel once switched the same module position, but still reported that “module I is not online”. Due to the lack of information, it is difficult to maintain. According to the inspection of the maintenance personnel, each module is an independent single board extension, which is controlled by a single chip microcomputer, and a single chip microcomputer is connected with the upper computer. According to the analysis of the function and processing technology of the module, the control modes of each module are different. Although the internal hardware of some modules is the same, the control procedures are different, so each module cannot be interchanged. After power on inspection, the self diagnosis function of the control system operates normally, and the alarm is “module I is not online”, so module I is specially inspected. There is no abnormality in module I through visual inspection. Power on and check that the CPU operation is normal, and the state of each integrated circuit is also normal. The check memory is EEPROM, which can be rewritten at any time. EPROM should be flexible and convenient in specific operation, but its reliability is not as high as EPROM. Due to some interference, misrewriting may occur, so it is suspected that the memory is faulty.
Troubleshooting: read out the contents of the memory and find several suspicious data. Disassemble it for analysis. The program will conduct self-test immediately after startup. If it fails, the upper computer will give an alarm. Look at the following control programs, some are not like formal programs or data. According to the mode analysis of the control program, some control programs have been rewritten, so they cannot pass the self-test. Write the control program according to the processing technology and verify it on PC. the self inspection can pass. Since there is no need to write data in actual operation, the EPROM curing program is rewritten. After power on inspection, module I will no longer alarm, and the whole machine can operate normally.
This example shows that maintenance personnel should not only be able to judge hardware faults, but also have certain knowledge of control software and be able to operate and use computers.
