Guangzhou Yunge Tianhong Electronic Technology Co., Ltd , https://www.e-cigaretteyfactory.com
First, the detection of ordinary diodes
Use the MF47 multimeter to measure, connect the red and black test leads to the two ends of the diode, read the reading, and then measure the test lead. Judging from the two measurements, the low power 锗 diode usually has a forward resistance of 300-500 Ω and a silicon diode of about 1 kΩ or more. The reverse-phase resistance of the manifold is several tens of kilo-ohms, and the reverse resistance of the silicon tube is above 500kΩ (the value of the high-power diode is much smaller). A good diode has a low forward resistance and a large reverse resistance. The larger the forward and reverse resistance differences, the better. If the measured positive and negative resistances are close to zero, it means that the inside of the diode is short-circuited; if the positive and negative resistances are large or tend to infinity, the inside of the tube is broken. In both cases the diode needs to be scrapped.
In the road test: test the diode PN junction forward and reverse resistance, it is easier to determine whether the diode is a short circuit or an open circuit.
Second, triode detection
Turn the digital multimeter to the diode file and use the meter to measure the PN junction. If it is conducting, the displayed digit is the forward voltage drop of the PN junction.
First determine the collector and emitter; use the test leads to measure the forward voltage drop of the two PN junctions, the emitter drop e is large, and the collector c is small. When testing two knots, the red pen is connected to the common pole, then the measured triode is NPN type, and the red test pen is connected to the base b; if the black pen is connected to the common pole, the measured triode is PNP type. And this is extremely base b. After the triode is damaged, the PN junction has both a breakdown short circuit and an open circuit.
In the road test: In the road test triode, actually by testing the positive and negative resistance of the PN junction, to determine whether the triode is damaged. The branch resistance is greater than the forward resistance of the PN junction. The normal and reverse resistances measured should be significantly different, otherwise the PN junction is damaged. When the branch resistance is less than the forward resistance of the PN junction, the branch should be disconnected, otherwise the triode cannot be judged. 
Third, three-phase rectifier bridge module detection
Take the SEMIKRON rectifier bridge module as an example, as shown in the drawing. Turn the digital multimeter to the diode test file, connect the black meter to the COM, the red meter to the VΩ, and use the red and black test leads to measure the forward and reverse diode characteristics between the 3, 4, 5 and 2 poles. Is the rectifier bridge intact? The larger the difference between the measured forward and reverse characteristics is, the better; if the positive and negative directions are zero, it means that the detected one phase has been broken through; if the positive and negative directions are infinite, it means that the detected phase has been broken. The rectifier bridge module should be replaced as long as one phase is damaged. Source: Transmission and Distribution Equipment Network
Fourth, MOS tube good or bad experience
1: Connected to the D pole with a black pen, the red pen is connected to the S pole, and generally has a resistance of 500-600.
2: Under the premise that the black test pen does not move, use the red pen to click on the G pole, and then use the red pen to measure the S pole, and the conduction will appear.
3: The red meter pen is connected to the D pole, the black meter pen point is below the G pole and then the S pole is measured. The resistance value is the same as the 1 measurement. The MOS tube works normally~~
The following method is summarized in the maintenance process. On the board, without the CPU, the resistance of S and G is directly hit. Less than 30 ohms are basically broken.
Digital multimeter method for measuring MOS tube: (using 2-pole tube file) method to remove bad tube test
Five, inverter IGBT module detection
Turn the digital multimeter to the diode test file to test the forward and reverse diode characteristics between the IGBT modules C1.E1 and C2.E2 and between the gate G and E1 and E2 to determine whether the IGBT module is intact.
Take the German eupec25A/1200V six-phase IGBT module as an example (see the attached figure). Remove the wires of the U, V, and W phases on the load side, use the diode test file, connect the red meter pen to P (collector C1), and the black test pen sequentially measures U, V, W (emitter E1), and the multimeter displays the value as the maximum; The test pen is reversed, the black pen is connected to P, the red pen is measured U, V, W, and the multimeter displays a value of about 400. Then connect the red meter to N (emitter E2), the black meter to measure U, V, W, the multimeter display value is about 400; the black meter is connected to N, the red meter is measured U, V, W (collector C2), and the multimeter displays the value. For the biggest. The forward and reverse characteristics of each phase should be the same. If the difference indicates that the performance of the IGBT module is deteriorated, it should be replaced. When the IGBT module is damaged, only the breakdown short circuit occurs.
The red and black test pens respectively measure the forward and reverse characteristics between the gate G and the emitter E, and the values ​​measured by the multimeter twice are maximum. At this time, it can be determined that the gate of the IGBT module is normal. If there is a numerical value, the gate performance deteriorates and the module should be replaced. When the forward and reverse test results are zero, it indicates that the detected one-phase gate has been broken through. When the gate is damaged, the voltage regulator of the circuit board protection gate will also be damaged by breakdown.
Sixth, the detection of electrolytic capacitors
When measuring with an MF47 multimeter, the appropriate range of the multimeter should be selected for electrolytic capacitors of different capacities. According to experience, in general, electrolytic capacitors below 47μF can be measured in R × 1K, and electrolytic capacitors larger than 47μF can be measured in R × 100.
Connect the multimeter red pen to the negative pole of the capacitor and the black pen to the positive pole. At the moment of contact, the pointer of the multimeter deflects to the right for a large extent, then gradually turns to the left until it stops at a certain position (returns to infinity position). The resistance at this time is the forward leakage resistance of the electrolytic capacitor. The larger the value, the smaller the leakage current and the better the capacitor performance. Then, the red and black test leads are reversed, and the multimeter pointer repeats the above swing phenomenon. However, the resistance measured at this time is the reverse leakage resistance of the electrolytic capacitor, which is slightly smaller than the forward leakage resistance. That is, the reverse leakage current is larger than the forward leakage current. The actual experience shows that the leakage resistance of electrolytic capacitors should generally be several hundred kilo ohms or more, otherwise it will not work properly.
In the test, if there is no charging phenomenon in the forward direction and the reverse phase, that is, the needle does not move, it means that the capacitor capacity disappears or the internal short circuit; if the measured resistance value is small or zero, the capacitor leakage is large or the breakdown is damaged. Can no longer be used.
In the road test: In the road test, the electrolytic capacitor should only be checked for serious leakage or breakdown failure, and the accuracy of the slight leakage or small-capacity electrolytic capacitor test is very poor. The road test should also consider the influence of other components on the test, otherwise the value read will be inaccurate and will affect the normal judgment. Electrolytic capacitors can also use a capacitance meter to detect the capacitance between the two ends to determine the quality of the electrolytic capacitor.
Seven, inductor and transformer simple test
1. Inductor test
Test the resistance of the inductor with the MF47 multimeter resistance file. If the resistance of the tested inductor is zero, it indicates that the internal winding of the inductor has a short circuit fault. Be sure to zero the multimeter and repeat the test several times. If the measured resistance of the inductor is infinite, it indicates that an open circuit fault has occurred at the winding of the inductor or the pin and the winding contact.
Source: Transmission and Distribution Equipment Network
2. Simple test of transformer
Insulation performance test: The resistance value between the core and the primary winding, the primary winding and the secondary winding, and the core and the secondary winding are respectively measured by the multimeter resistance file R×10K, and should be infinite. Otherwise, the transformer insulation performance is poor.
Measuring winding continuity: use the multimeter R×1 file to measure the resistance between the primary and secondary windings of the transformer. Generally, the resistance of the primary winding should be tens of ohms to several hundred ohms. The smaller the power of the transformer, the larger the resistance value; The secondary winding resistance value is generally several ohms to several hundred ohms. If the resistance value of a certain group is infinite, the group has an open circuit fault.
Note: This measurement method is only a rough estimate. Some transformers with short windings between winding turns are inaccurate.
Eight, simple resistance test of resistors
To cut off the power of the circuit board when measuring the resistance of the circuit, consider the influence of other components in the circuit on the resistance value. If a capacitor is connected to the circuit, the capacitor must also be discharged. The multimeter's hands should refer to the center of the scale and the readings are accurate.
Nine, patch components
1. SMD type of components
Most of the inverter electronic circuit board using SMD components are now also referred to as surface mount components, which is a very short leads or leadless surface mount adapted to miniature electronic components. There are many kinds of chip components, which can be divided into rectangular, cylindrical and special-shaped structures according to the shape. According to the type, it can be divided into chip resistors, chip capacitors, chip inductors, chip semiconductor devices (which can be divided into chip diodes and chip transistors), and chip integrated circuits. Source: Transmission and Distribution Equipment Network
2. Disassembly and soldering of chip components
Use 35W internal heating soldering iron with long life and oxidation resistant tip. Wipe off the sticky residue on the tip, leaving only a thin layer of solder. The chip component removal and soldering operations of the devices at both ends are relatively easy. The chip type integrated circuit has fine pins and a small pin pitch, and the surrounding components are arranged in a compact manner, and the assembly and disassembly are not easy. Their disassembly and soldering are difficult without special tools. The disassembly and soldering operations of the chip integrated circuit are highlighted here.
3. Disassembly method
If it is determined that the integrated circuit block is damaged, use a paper cutter to cut the pins and remove the integrated circuit block. Note that the cutter head should not be cut to the circuit board during cutting. Then, use a pair of tweezers to hold the broken foot, use a pointed iron to dissolve the solder on the broken leg, and remove the broken foot one by one.
4. Welding method
Before soldering, clean the excess solder and dirt on the copper plate of the circuit board with the integrated circuit block. Apply the alcohol loose perfume to the pins of the integrated circuit block and apply a thin tin to the pins. . Then, check the position of the integrated circuit pins, place the integrated circuit block on the circuit board to be soldered, lightly press the integrated circuit block, and solder the pins on the four corners of the integrated circuit block with the soldering iron to fix the integrated circuit block. Well, solder one by one pair of other pins. In order to ensure the quality of the welding, it is better to use a thinner solder wire, such as 0.6mm solder wire, for better soldering.
In the maintenance process, according to the fault situation, the multimeter should be used to detect the quality of the electronic components. If the measurement method is incorrect, it may lead to misjudgment, which will cause difficulties in maintenance work and even cause unnecessary economic losses. The measurement method is divided into two methods: component testing and circuit board testing. In the road test: disconnect the inverter power supply, and measure the components on the circuit board without disassembling the components of the circuit board. For component breakdown, short circuit, open circuit fault, this detection method can find out the damaged components conveniently and quickly, but also should consider the influence of the components measured on the circuit board and the components connected in parallel on the measurement results. In order to avoid misjudgment errors. The following describes the method for judging the quality of components: