Genuine / Original COMPAQ 18.5v 4.9a AC Adapter In Southeast Asia

Question Related COMPAQ 18.5v 4.9a laptop ac Adapter ( From internet ):

Why is the COMPAQ 18.5v 4.9a power adapter suddenly broken?

1. Adapter output voltage too high: Too high output voltage generally comes from the voltage regulation sampling and voltage regulation control circuit. In the closed control loop composed of DC output, sampling resistor, error sampling amplifier such as TL431, optocoupler, power control chip and other circuits, any problem with any part of it will cause the output voltage to rise.
2. Line failure: adapter Line faults, including damage to the power line and failure to energize, oxidation of the contact port and poor contact, etc., focus on checking whether the input line and output line are energized. If the line is faulty, it can be solved by replacing the power cord, etc.
3. Adapter fuse burnt or blown: Mainly check the rectifier bridge, each diode, switch tube, and the large filter capacitor on the 300 volts, which may cause the fuse to burn and blacken, or it may be caused by a problem with the anti-interference circuit. It is especially worth noting that the fuse is burned due to the breakdown of the switch tube, which usually burns out the power control chip and the current detection resistor. The thermistor is also easily burned out together with the insurance.
4. Adapter output voltage is too low: The main reason for the low output voltage: the performance of the switch tube is degraded, which leads to the failure of the switch tube to conduct normally, which increases the internal resistance of the power supply and reduces the load capacity; the filter capacitor is poor, resulting in poor load capacity of the power supply, and the output voltage drops when the load is connected. will drop; the switching transformer is not good, not only causes the output voltage to drop, but also causes insufficient excitation of the switch tube and damages the switch.

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