Switching Power Supply Chirping, How to Fix?

by user1596683   Last Updated July 12, 2019 05:25 AM

I have a Dedicated Micros UP07223010 power supply that gives out a chirping noise. A voltmeter attached to the terminals shows a swing for each chirp. A few days ago, my HP laptop power supply developed the same chirping problem and had to be replaced. So I assume it is quite common. Here is a picture of the interior. The three bigger capacitors near the center with gold marking (3300 uF, 16V) look to be a bit bloated. Could they be the problem? enter image description here

Tags : power-supply

Answers 1

'Chirping' comes from the power supply restarting over and over again. The typical cause is an external overload, but defective internal parts can cause the same effect. The power supply is trying to run but is encountering an over current condition that prevents the output voltage from rising to a preset level by a preset timeout of one second or less.

You mentioned bloated capacitors. Generally it is a single part that fails, either a diode or capacitor in the output stage. However a component failure in the feedback loop can cause the same effect.

Note that over time constant restarts will burn out the control IC or MOSFET. Testing with a good DVM could help find out where the proper rise in output voltage is being cutoff. Be careful! The primary side has about 240 to 340 vdc, very painful to touch.

July 12, 2019 05:12 AM

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