First, because the quality of the power supply itself is not good, the internal power supply can not withstand the load for a long time and is burned out.
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Second, because the input voltage is unstable or contains high-frequency clutter. Check whether the plug socket is in poor contact, whether there are high-power or high-frequency electrical appliances around, etc., you can also install a voltage regulator or UPS to improve.
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Third, the load has a slight short circuit or intermittent short circuit resulting in the power supply being burned out.
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Fourth, the aging of the device caused by burning, electronic devices have a certain use period, when long-term use, oxidation and performance changes will cause instability of the overall circuit work, resulting in damage.