In the absence of any schematic diagram, to repair a relatively unfamiliar injection molding machine circuit board, so-called "experience" in the past is difficult to do. Although people with deep knowledge of hardware are full of confidence in repairs, if method is not right, work will still be less effective. So, what can be done to improve maintenance efficiency? Based on experience of long-term injection molding machine maintenance, it is concluded that following steps should be followed and carried out in an orderly manner.

 

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 printed circuit board connection line on circuit board of injection molding machine is broken, stuck, etc.;
4. Has anyone repaired it? Which components have been moved? Whether there are operational errors such as virtual welding, missing welding, and reverse insertion;
After confirming that the repaired parts do not have the above conditions, first use a multimeter to measure resistance between power supply and ground of injection molding machine circuit board. If resistance is too small, it is only a few or a dozen ohms, indicating that there are components on circuit board of injection molding machine that are broken down or partially broken down, measures must be taken to find broken down components.
Specific method is to supply power to circuit board to be repaired, touch temperature of each component on circuit board of injection molding machine with your hands. Those who are hot will be key suspects. If resistance value is normal, use a multimeter to measure discrete components such as resistors, diodes, transistors, FETs, and DIP switches on board. Purpose is to first ensure that measured components are normal. Our reason is that problem that can be solved with a multimeter should not be complicated.

Tools used: circuit online maintenance instrument
If situation allows, it is best to find a good board that is same as board to be repaired as a reference, then use dual-rod VI curve scanning function together to perform a good and bad comparison test on two boards. Initial comparison point can start from port, then from outside to inside, especially comparison test of capacitance, can make up for shortcoming that multimeter is difficult to detect whether there is leakage online.

Tools used: circuit online repair instrument, electric soldering iron, marker
In order to improve test effect, before online functional test of circuit board of injection molding machine, some technical treatment should be done on repaired board to minimize negative impact of various disturbances on test process. Specific measures are:
1. Preparation before test
Short-circuit crystal oscillator, and solder a foot to large electrolytic capacitor to make it open, because charging and discharging of capacitor can also cause interference.
2. Use exclusion method to test device
During online test or comparison of device, for any device that passes test (or is relatively normal), please directly confirm test result for recording; if test fails (or is out of tolerance), you can test it again. If it still fails, you can also confirm test results first, keep testing like this until devices on board are tested (or compared), then go back to deal with those that fail test (or comparatively poor) devices.
For devices that fail functional online test, instrument also provides a less formal but more practical processing method, because power supply of instrument to circuit board of injection molding machine can be applied to corresponding power supply and ground of device through test clip. If power pin of device is cut, device will be separated from power supply system of circuit board of injection molding machine. At this time, online function test of device will be performed. Since other devices on circuit board of injection molding machine will no longer interfere, actual test effect is equivalent to "quasi-offline", and accuracy rate will be greatly improved.
3. Use ASA-VI curve scan test to compare and test devices not covered by test library
Because ASA-VI intelligent curve scanning technology can be applied to comparison test of any device, as long as test clip can clamp device, and there is a reference board, through comparison test, it also has a strong fault detection ability for device. This function makes up for deficiency that online functional test of device is subject to test library, and expands detection range of instrument to failure of circuit board of injection molding machine.
In reality, it is often impossible to find a good board for reference, and circuit structure of board to be repaired does not have any symmetry. In this case, ASA-VI curve scan comparison test function does not work, and online functional test does not work. Due to incomplete device test library, it is impossible to test every device on injection molding machine circuit board, and injection molding machine circuit board still cannot be repaired. Here is limitation of circuit online repair instrument, just like there is no cure for all diseases. .

Since circuit online maintenance instrument can only perform functional online test and static characteristic analysis on components on circuit board of injection molding machine, whether it is completely repaired must be tested by the whole machine. It is correctly supplied to circuit board of injection molding machine as required.