As shown in the figure, this is a relay found in parallel with a diode. On the PCB board, how to measure D3 with an instrument?
Caitlin ポストする October 27, 2020
Use a pointer type multimeter to resist X1 gear, and both ends of the primary relay winding for each quantity in the forward and reverse directions. The difference in the resistance value measured twice is the existence of D3.
When the red test pen of the analog multimeter is connected to 12V, the measured resistance is small, and the D3 direction is correct.
Callum ポストする October 27, 2020
Divide it twice, add a current-limiting 12V DC voltage from both ends, and then measure the voltage drop. If the voltage is equal, D3 is broken, if one is large, the other is normal. If it is 12V, or 0V, the relay and D3 are both broken
Brady ポストする October 27, 2020
Regardless of whether the relay winding is tested in the forward or reverse direction, it is the same, but if a diode is connected in parallel, the forward and reverse directions are different.
