Causes and solutions of power adapter not connecting to load and no voltage If the power adapter is not connected to the load and the measured voltage drops from 12 volts to 1 volt or no voltage, it means that the power adapter is caused by damage to components, and the fault is generally caused by rectifier diodes, filter capacitors and other components.
Whether it is a tablet, wireless router, network set-top box or other electrical appliances, when the power adapter has no voltage output, it means that the power adapter has damaged components.
Specific inspection method: Measure the output voltage of the power adapter with a pointer multimeter 50 volts or a digital multimeter 200 volt voltage range. If the voltage measured when not connected to the load (i.e., not plugged into the appliance) is around 0 or 1 volt, it is clear that the power adapter is faulty.
For some small power adapters, most of them are disposable and cannot be disassembled smoothly. It is not as easy to remove as the charging head of some jukeboxes. This power adapter housing seems to be one-piece, not easy to open or cannot be opened directly. I once repaired the power adapter on my wireless router. The fault phenomenon is that the power output voltage of 12V is 0, and we cannot disassemble it normally, so we have to use a saw blade to slowly pull out the power adapter from the middle along the sealing line. Then, after measurement and inspection, the rectifier output diode is damaged due to short circuit, replace the high-power rectifier diode, measure the output of 12 volts with a multimeter, and troubleshoot.
For small power adapters like the one mentioned above, if the output voltage of 12 volts becomes around 0 or 1 volt, most of the rectifier diode or filter capacitor is damaged. Simply replace the damaged components. If the fault is not completely eliminated after replacing the wearing parts, it is recommended to purchase a new power adapter of the same type. When replacing the power adapter, pay attention: the voltage polarity of the power output must be the same as that of the original power adapter, otherwise even a good power adapter will not work properly, causing misjudgment and misunderstanding that the electrical appliances used are damaged. This must be noted.
There is also a power adapter currently used in LCD TVs, generally used on small LCD TVs of about 17 inches. This power adapter typically outputs 12 volts. This power adapter is relatively large, and the components used in it are also better, so it is generally not easy to fail.
If this power adapter has no output voltage or the voltage is very low, the repair method is basically the same as that of a small power adapter. Mainly check whether the rectifier diode, filter capacitor and other components are damaged, and replace the damaged components. If the power adapter fails or is still not working properly after replacing the obviously damaged parts, it is recommended to purchase the same model of power adapter directly. The precautions are as mentioned above and will not be repeated here.
The above mainly introduces two types of power adapters. When the 12-volt output voltage becomes 0 volts or 1 volt, the repair method and treatment recommendations are introduced.
