How to measure a rectifier bridge with a multimeter?
Rectifier bridge is the four rectifier diodes (will be converted to DC energy semiconductor components) according to the bridge structure in series, series up after the package together (plastic package), with four rectifier diodes composed of bridge rectifier, rectifier bridge has a positive and negative points, which - the foot of the DC compression out of the end. -Generally connected to the load or after filtering, regulator connected to the load, and supply DC energy to the load.
1, measured one by one, also known as one by one measurement method
Diode characteristics should be clear (large reverse resistance, forward resistance is small), diode good or bad, with a multimeter can be measured. In a paper to identify diodes and diodes good and bad measurement at the end of out previously introduced, do not understand can go to see, more understandable, this side will not repeat previously introduced.
Measurement of resistance range under normal circumstances than the
Measurement data derived from the resistance value and judge the range, you can use the measured data for comparison.
The above method of testing rectifier bridge stack detailed and reliable, but the test process is more cumbersome. Here is another simple method, you only have to measure three times to determine the bridge stack good or bad.
Measure the rectifier bridge pins with a multimeter
In the text of the internal structure of Figure 1 shown at the multimeter set R × 10k file. Measurement of AC power input ② feet, ④ feet between the forward and reverse resistance, from the circuit structure can be seen, regardless of how the two pens are connected to the measurement, for a good performance of the bridge, its ② feet, ④ feet between the forward and reverse resistance should be very large, because each measurement there is always a diode is reversed using the state; if the measured forward and reverse resistance is small (eg, only a few thousand ounces), then it shows that the pile of petite or more diode breakdown or leakage phenomenon, can no longer use the diode, and the bridge can not be used. Leakage phenomenon, can no longer be used.
Functional description of each part of the multimeter
Of course, relying on this type of method may not be able to completely determine which tube is damaged in the bridge stack. Therefore, should also continue to measure the DC output ① foot, ③ foot between the forward resistance, the method is: multimeter set R × 1k file, the red pen connected to ③ foot. Black pen to ① foot, if the measured forward resistance is slightly larger than the single diode forward resistance, indicating that the bridge quasi-normal, if the forward resistance is close to the single diode forward resistance, indicating that the bridge weir in a one or two (two buttocks) diode breakdown; if the forward resistance is larger than the two diode forward resistance is much larger than the diode forward resistance of the bridge quasi-diode forward resistance or open-circuit failure.
By the bridge quasi-pin location of the discernment (the following pin position are Figure 1 internal structure of the pin position marked)
Internal structure can be seen, the location of the pin has been marked on the bridge pile of the shell, a look can be determined, but some of the bridge pile marking is not clear, or marking there is a mistake, you can not blindly access the circuit, otherwise it will burn the bridge pile and other components, compared to the need to use a multimeter to determine the exact location of the bridge pile pins.
Rectifier bridge pin function and symbol marking (Figure pin position ≠ text pin position)
Judgment method is: first find the positive DC output (i.e., ③ feet) end, assuming that a foot for ③ feet. Multimeter set R × 1K file, the red pen according to ③ feet, with the black pen were to connect ① feet, ② feet, ④ feet, if the three times there is a small resistance (on-resistance) is that the assumption is correct, that is, ③ feet for the bridge stack of the positive DC output, if the three tests, a foot through or not pass, it is assumed that the wrong Na, need to be assumed that ② feet to re-test until you find the real ② feet.
Find ③ feet, the rest of the foot will be good to determine: still use the red pen to connect the ③ feet, with a black pen to test the other three feet of the positive resistance, which has the largest resistance value of the foot print for the negative end of the DC voltage output, the remaining two feet for the AC input, there is no positive or negative polarity points. (The pointer multimeter used here, if you use a digital multimeter, you can also use the diode test file, but note that the digital multimeter red pen connected to the positive terminal of the internal battery, so the pen order is the opposite of the above method.)
