Injection molding machine computer board maintenance skills
To repair a relatively unfamiliar circuit board of an injection molding machine without any schematics Do more with less. So, what can be done to improve maintenance efficiency? Based on long-term experience, SUDA concluded that the following steps should be followed in an orderly manner.
Method 1: Look first and then measure
Tools used: multimeter, magnifying glass
When holding a circuit board of an injection molding machine to be repaired, it is a good habit to first inspect it visually, and if necessary, use a magnifying glass to see what?
Mainly see:
1. Is there a disconnection?
2. Disconnection of discrete components such as resistors, electrolytic capacitors, inductors, diodes, triodes, etc.;
3. Whether the printed circuit board connection line on the circuit board of the injection molding machine is broken, stuck, etc.;
4. Has anyone repaired it? Which components have been moved? Whether there are any mistakes in operation such as virtual welding, missing welding, reverse insertion, etc. After confirming that the repaired parts do not have the above conditions, first use a multimeter to measure the resistance between the power supply and the ground of the circuit board of the injection molding machine. If the resistance is too small, It is only a few or a dozen ohms, indicating that there are components on the circuit board of the injection molding machine that are broken down or partially broken down, and measures must be taken to find the broken down components. The specific method is to supply power to the circuit board to be repaired, and touch the temperature of each device on the circuit board of the injection molding machine by hand. The hot hand will be the key suspect. If the resistance value is normal, use a multimeter to measure discrete components such as resistors, diodes, transistors, FETs, and DIP switches on the board. The purpose is to first ensure that the measured components are normal. Our reason is that we can use a multimeter Solve the problem, don't complicate it. string 1
Method 2: First outside and then inside
Tools used: circuit online maintenance instrument
If the situation allows, it is better to find a good board that is the same as the board to be repaired as a reference, and then use the dual-rod VI curve scanning function to perform a good and bad comparison test on the two boards. The initial comparison point can start from the port, Then from the outside to the inside, especially the comparative test of the capacitance, it can make up for the shortcoming that the multimeter is difficult to detect whether there is leakage online.
Method 3: Easy first and then difficult
Tools used: circuit online repair instrument, electric soldering iron, marker
In order to improve the test effect, before the online functional test of the circuit board of the injection molding machine, some technical treatment should be done on the repaired board to minimize the negative impact of various disturbances on the test process. The specific measures are:
1. Before the test, short-circuit the crystal oscillator, and weld a foot to open the large electrolytic capacitor, because the charging and discharging of the capacitor can also cause interference.
2. Use the exclusion method to test the device. During the online test or comparison process of the device, for any device that has passed the test (or is relatively normal), please directly confirm the test result for recording; , you can test it again, if it still fails, you can also confirm the test results first, and keep testing until the devices on the board are tested (or compared), and then go back to deal with those that failed the test (or comparison). out of tolerance) devices. For devices that fail the functional online test, the instrument also provides a less formal but more practical processing method, because the power supply of the instrument to the circuit board of the injection molding machine can be applied to the corresponding power supply and ground of the device through the test clip. If the power pin of the device is cut, the device will be separated from the power supply system of the circuit board of the injection molding machine. At this time, the online function test of the device will be performed. Since other devices on the circuit board of the injection molding machine will no longer interfere, the actual test The effect is equivalent to "quasi-offline", and the accuracy rate will be greatly improved.
3. Use the ASA-VI curve scan test to compare and test the devices not covered by the test library
Because the ASA-VI intelligent curve scanning technology can be applied to the comparison test of any device, as long as the test clip can clamp the device, and there is a reference board, through the comparison test, it also has a strong fault detection ability for the device. This function makes up for the deficiency that the online functional test of the device is subject to the test library, and expands the detection range of the instrument to the failure of the circuit board of the injection molding machine. In reality, it is often impossible to find a good board for reference, and the circuit structure of the board to be repaired does not have any symmetry. In this case, the ASA-VI curve scan comparison test function does not work, and the online functional test does not work. Due to the incomplete device test library, it is impossible to test every device on the injection molding machine circuit board, and the injection molding machine circuit board still cannot be repaired. Here is the limitation of the circuit online repair instrument, just like there is no cure for all diseases. .
Method 4: Be still and then move
Since the circuit online maintenance instrument can only perform functional online test and static characteristic analysis on the components on the circuit board of the injection molding machine at present, whether it is completely repaired must be tested and inspected by the whole machine. Requires correct supply to the injection molding machine circuit board.
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Injection molding machine computer board maintenance skills
