1. When using the multimeter ohms, remember not to measure with electricity.
2. When using a logic pen or oscilloscope to detect signals of Pocket Ethernet Tester, be careful not to make the probe touch the two measurement pins at the same time, because the essence of this situation is to form a short circuit under power-on.
3. When detecting the filter capacitor in the power supply, first short-circuit the positive and negative poles of the electrolytic capacitor, and do not use the test lead wire instead of the wire to discharge the capacitor when short-circuiting, because it is easy to blow the core wire. You can take a 220V, 60 ~ 100W lamp with a lamp lead, connected to the two ends of the capacitor, the bulb will flash when the battery is discharged.
4. When repairing the China Lan Network Checker fault in a humid environment, it is necessary to measure the smoothness of each point on the printed circuit with a multimeter, because the main fault in this case is copper foil corrosion.