Method for locating faults in electrical control circuits using a multimeter
Finding line faults generally have voltage method and resistance method. Voltage method is the use of voltage measurement to detect faults, resistance method is the use of resistance measurement to find faults. They have their own advantages, if the line is not familiar with, we recommend using the resistance method to determine the fault, relatively safe.
The main line wire is relatively small, judge the fault is relatively easy, here take the control line as an example.
Before measuring the control line, disconnect the control line power supply/fuse to keep the control line separate from the main line. The purpose of this is to measure the control line without interference from the main line.
Then one meter pointer is placed at the odd starting number of the control circuit (e.g. 101) and the other meter pointer is placed at the even starting number of the control circuit (e.g. 102), and the resistance value should be infinitely large between them. Then press the pushbutton switch SB2, which should have a certain resistance value (resistance value equal to the coil resistance). If the resistance is still infinite, it means that the two pens do not work, somewhere broken, then go on to find out.
No hand to press the button, we can use a short wire or other metal objects to short the button up, and then remove it after the test.
Then we press the button again and measure the resistance between the next terminal from the start terminal (103) and the even start number (102). If there is some resistance, there is a break between 101 and 103. If the resistance is still infinite, there is still a break somewhere between 103 and 102, so move on to the next one.
And so on, until we find the point of failure
Because the numbering rules determine the end of the odd and even are two different polarity lines, so we measure the end of the odd terminal and even terminal, there is a certain resistance between them normally. (Provided, of course, that the same power circuit)
