Instruction
1
If marking is available, note its appearance and location. It looks like the arrow rests on the plate. The direction of the arrow coincides with the forward direction of the current flowing through the diode. In other words, the arrow corresponds to the anode terminal, a plate - cathode.
2
Analog multi-function measuring devices have different polarity of the voltage applied to the probes of the ohmmeter. Some of them she's just like using a voltmeter or ammeter, others - the opposite. If it is unknown to you, take a diode, marked, switch off the device to the ohmmeter, then connect to the diode first in one and then in the other polarity. In an embodiment in which the needle, remember which electrode of diode were connected to which of the probes. Now, connecting the probes at different polarity to other diodes, you will be able to determine the location of their electrodes.
3
Digital devices in most cases, the polarity of the probe in all modes is the same. Switch the multimeter mode of the diode is next to the switch there is a designation of that part. The red test lead corresponds to the anode, black - cathode. Correct polarity will show the forward voltage drop across the diode in the wrong is indicated by the same infinity.
4
If the measuring device is not, take the battery from the motherboard, a led and a resistor to one kilo Ohm. Connect them in series by connecting the diode in such a polarity to the led light. Now include the gap of this circuit check the diode, experimentally picking up a polarity to the led lit up again. The output of the diode facing the positive battery anode.
5
If you review the impact that the diode is permanently open or permanently closed, and the polarity does not depend on anything, then it is faulty. Replace it, after making sure that his failure is not due to a malfunction of other parts. In this case, first replace them.