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, is there any disconnection
, is there any disconnection in component components such as resistors, electrolytic capacitors, inductors, diodes, transistors, etc.
, is the printed board connecting wire on the circuit board There are breaks, adhesions, etc.
Has anyone repaired it? What components have been moved? Whether there are any operational errors such as weak soldering, missing soldering, reverse insertion, etc.
After confirming that the above conditions have not been repaired, first use a multimeter to measure the resistance between the circuit board power supply and the ground. Usually the resistance of the circuit board Are you all there? Above, if the resistance value is too small, only a few or more than a dozen ohms, it means that there is a breakdown or partial breakdown of a component on the circuit board, and measures must be taken to find out the breakdown components. The specific method is to supply power to the board to be repaired, and touch the temperature of each component on the circuit board with your hands. The lecturer who feels hot is the main suspect. If the resistance value is normal, use a multimeter to measure the resistance, diodes, transistors, field effect tubes, dial switches and other component components on the board. The purpose is to first ensure that the measured components are normal. Our reason is that it can be used When a multimeter solves a problem, don't complicate it.
Method 2: First outside and then inside
Tools to use: circuit online repair instrument
If circumstances permit, it is best to find a good board that is the same as the board being repaired as a reference, and then use them together The dual-rod curve scanning function performs a good and bad comparison test on two boards. The initial comparison point can start from the port, and then from the outside to the inside. Especially the comparison test of capacitance can make up for the difficulty of using a multimeter to detect leakage online. Shortcomings.
Method 3: Easy first, then difficult
Tools to be used: circuit online repair instrument, soldering iron, marker
In order to improve the test effect, before conducting online functional testing of the circuit board, the repaired The board undergoes some technical processing to minimize the negative impact of various interferences on the test process. The specific measures are:
Preparation before testing
Short-circuit the crystal oscillator, and solder a leg of a large electrolytic capacitor to make it open circuit, because the charging and discharging of the capacitor can also cause interference.
Use the elimination method to test the device
During the online testing or comparison process of the device, for any device that passes the test (or is relatively normal), please directly confirm the test results so that the failure of the test can be recorded ( or relatively out of tolerance), you can test it again. If it still fails, you can also confirm the test results first, and keep testing like this until the devices on the board are tested (or compared), and then go back to deal with those Devices that fail the test (or are out of tolerance). For devices that fail the functional online test, the instrument also provides a less formal but more practical processing method. Since the power supply of the circuit board by the instrument can be applied to the corresponding power supply and pin of the device through the test clip, if the device is If the power pin of the circuit board is cut, the device will be separated from the circuit board power supply system. At this time, the device will be tested online. Since other devices on the circuit board will no longer interfere, the actual test effect is equivalent to quasi-offline. The measurement accuracy will be greatly improved. .
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Xiamen Yingyi Automation Technology Co., Ltd.
Contact person: Fu Maoqiang
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Xiamen Yingyi Automation Technology Co., Ltd.
Contact: Fu Maoqiang
Contact number
Mobile phone number
&QQ number
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