Detection of the patch based pressure sensitive resistor and the detection technique of the fixed patch resistor
How to do a good job? What is the testing technique of the fixed patch resistor? I believe there are friends to worry about this! So how to face these should be how to operate better? Now by the small make up one by one for everyone to answer it.
Patch voltage varistors with both ends of the resistance value changes. When the voltage is greater than a certain value, the resistance decreases sharply when the voltage is normal, the resistance value can return to normal. Overvoltage protection circuit.
How to do a good job?
A simple method for the detection of the patch voltage sensitive resistor is as follows:
The multimeter dial to 10K ohm, measuring its resistance, normal should be infinite. If the hand is patch deflection, varistor leakage current and poor quality, should be replaced.
What is the testing technique of the fixed patch resistor?
Detection of fixed chip resistors, mainly to test the practical value and the nominal resistance is consistent. It is generally used to measure the ohm profile of the universal meter, and the common detection methods are "in the way of resistance detection method" and "open circuit resistance detection method".
(1) the detection of resistance in the road
Resistance is measured in the way resistance is the resistance value that is measured when the chip resistor is welded on the PCB board. Measuring the resistance value of the patch resistor in the way with the universal meter.
The appropriate range of the multimeter ohm range, two probe on resistor two pin joints, measured a resistance. The red and the black pen exchange once, take another test resistance, large resistance as a reference value for R on the road, there are the following three situations.
The R is greater than the measurement of chip resistor nominal resistance on the road. If the measured results can directly determine the existence of open circuit or chip resistor resistance increases, the chip resistor is damaged.
The R on the road is very close to the measured chip resistor nominal resistance. If this result is measured, it can be judged that the chip resistor is normal.
Nominal resistance chip resistor R as measured in the distance less than or close to 0. If this kind of result is measured, it is not sure that the patch resistor is short circuit, and the circuit should be further analyzed in parallel with the chip resistor. For example: if there is a parallel branch coil, the measured resistance is the DC resistance of the coil, and the DC resistance of the coil is generally a few ohms. This situation can be used in the back of the open circuit resistance measurement to further check.
(2) the detection of open circuit resistance
Open circuit resistance is the resistance value measured by the resistor from the printed circuit board. Open circuit detection can be carried out when the value of the resistance measurement in the road is in doubt. Measurement of the open circuit resistance of a patch resistor with a universal meter.
The appropriate range of the multimeter ohm range, two probe connected resistor two pins, the measured values of the actual value of the resistor, set to open R, there are the following two situations:
R open the nominal resistance equal to or close to the measurement of chip resistor. If this result is measured, it can be judged that the chip resistor is normal.
The R circuit is far greater than the nominal resistance measured by the SMD resistor. If the measured results, indicating that the chip resistor resistance value increases. When the measured value tends to infinity, the internal circuit chip resistor.
The above information content for the Shenzhen science and technology professional technical director tage, written by professional technology small, hope our friends to adopt only this reference. Thank you for viewing the original text!
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