1. chip with program

1. EPROM chip should not be damaged. Because this chip needs ultraviolet light to remove the program, the program will not be damaged in the test. However, some information introduces: Due to the material of making chips, over time (the age is long), it may be damaged even if it does not need to be used. So backup as much as possible.

2. EEPROM, SPROM, and RAM chips with batteries are very easy to damage programs. Whether this type of chip uses the <Tester> Vi curve scan, whether the program is destroyed, it has not yet been concluded. Nevertheless, when you encounter this situation, colleagues are careful. The author has done many tests. The large reason may be caused by the leakage of the inspection tool (such as the tester, the electric iron).

3. Do not easily remove it from the board with a chip with a battery on the circuit board.

Second, reset circuit

1. When there are large -scale integrated circuits on the circuit board, pay attention to the problem of reset.

2. It is best to install it back to the device before the test, repeat it, and try it. And press a few more reset keys.

3. Function and parameter testing

1. <Tester> The detection of the device can only reflect the deadline, amplify and saturated areas. However, the specific values of the working frequency and the speed of speed and speed of the working frequency cannot be measured.

2. Similarly, for TTL digital chips, you can only know that there are high and low level output changes. It cannot find the speed of its rise and falling edge.

4. Crystal oscillator

1. Usually, only oscilloscope (crystallization needs to be powered up) or frequency meter testing, universal tables, etc. cannot be measured, otherwise it can only be used for replacement method.

2. Common faults of crystal vibrations include: 1) Internal leakage 2) Internal opening 3) Mochgrimed frequency bias 4) The peripheral capacitor leakage is connected to the periphery. The leakage phenomenon here should be measured with the VI curve of the <Tester>.

3. Two judgment methods can be adopted during the whole plate test: 1) During the test, the relevant chips around the crystal not passed. 2) No other fault points were found except the crystal.

4. There are two types of crystals: two feet, four feet, and the second foot is added with a power supply. Be careful not to be short -circuited at will.