Repairing Guides

how to repair a switching power supply

by Prof. Elmo Daugherty Published 2 years ago Updated 2 years ago
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How to Fix a Switch Mode Power Supply

  1. Knowledge of Components Make sure you familiarize yourself with the components that are available in the power supply. ...
  2. Protection Circuit I thought I should just mention that a switch mode power supply is well preserved by what is known as protection circuit. ...
  3. Shorted Components within the Primary Side

Full Answer

How to fix a switching power supply?

Switching power supply repair guide. Repairing the switching power supply can be processed in two steps: 1. In case of power off, users can carry out maintenance by visual check, smelling, asking and measuring. Visual check: Open shell of the power supply to check whether the power fuse has been blown. Check internal part of the power supply.

How to jumpstart power supply?

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How to repair SMPS power supply?

Which means that the mosfet might have stopped osculating causing a short circuit through itself, allowing the entire AC to go through the components within the input supply line. How to Repair the SMPS Circuit. The shown burnt SMPS can be repaired with the following simple steps. 1) Remove the mosfet from the PCB and check it with a multimeter

How to repair a PC power supply?

Method 3 Method 3 of 3: Replacing a Failed PC Power Supply Download Article

  1. Purchase a new power supply of the same type as the old one. ...
  2. Unpack the new power supply and make sure it physically fits correctly. ...
  3. Using proper ESD procedures, connect the devices in your PC to the new power supply. ...
  4. Verify that no cables or unused connectors are stuck in the CPU fan or touching other moving parts. ...

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Can power supply be repaired?

If, after troubleshooting your computer power supply, you determine that the power supply is bad, we recommend it be replaced. Because of the potential hazards associated with repairing a power supply, most computer repair shops and computer companies do not repair power supplies and instead replace them for new ones.

What usually fails in switching power supply?

Typically, only a small number of components fail in switching-regulator power supplies. The most common failure is the switching transistors themselves. The transistors short-circuit, causing massive amounts of current to be drawn across the transformer, blowing the input line fuse.

Can SMPS be repaired?

The shown burnt SMPS can be repaired with the following simple steps. 3) After changing the mosfet make sure to change the burnt rectifier diode also, and ideally change all the 4 diodes in the bridge, to ensure no weakened diodes are present in the network.

How do I test a switching power supply?

Step-by-Step Output Power Measurement – Output Ripple AnalysisClear any existing settings from previous tests by selecting Default Setup.Press Analyze and select the Power application. Choose Output Ripple.Connect your probes. Connect a voltage probe to the output of your supply. See Figure 3. ... Press AutoSetup and Apply.

What are the symptoms of SMPS failure?

Symptoms of a failing computer power supply Random computer crashes. Random blue screen crashes. Extra noise coming from the PC case. Recurring failure of PC components.

How do I know if my SMPS is bad?

Turn on the SMPS with the wire inserted. The SMPS should be running now. If it does not turn ON, insert the paper clip firmly and try once more. If still your SMPS didn't turn ON, your SMPS might be faulty.

What should I do if SMPS is not working?

Take a small piece of wire and connect one end in GREEN wire port and other in the BLACK. Switch ON the supply if the fan in the smps is working the smps is good. If not open the cover and check whether the Capacitors inside the Smps is bulged on the top.

What is SMPS and troubleshooting?

SMPS is referred to as Switched Mode Power Supply. It is a device that efficiently provides a regulated voltage, from a different level of input voltage. The device transfers the power from a source (basically an electrical grid) to the computer system.

How do you fix a power circuit?

3:286:19How to Repair a Circuit Board (from the top) - YouTubeYouTubeStart of suggested clipEnd of suggested clipI'm going to try to heat up my component here so apply some heat onto. These two pins for a littleMoreI'm going to try to heat up my component here so apply some heat onto. These two pins for a little bit. And then after that I'll try putting my saturn soldering iron through these holes briefly.

How do I use a multimeter to test a switching power supply?

Plug the PSU into an outlet and flip the switch on the back. You should hear a fan. Test every pin on the 24-pin motherboard power connector as indicated in this article. Record voltage and confirm within accepted tolerances.

How can I test my power supply without a motherboard?

0:031:31How to turn on PC Power supply without a motherboard. How to test ...YouTubeStart of suggested clipEnd of suggested clipWe need to short together green wire which is power on to any of ground black wire I'm gonna useMoreWe need to short together green wire which is power on to any of ground black wire I'm gonna use this paper clip which is enough for testing purposes anyways. We can make a switch between these.

What is a switching power supply used for?

Switching power supplies are primarily used in digital systems such as telecommunication devices, computing equipment, audio equipment, mobile phone chargers, medical test devices, arc welding equipment and automotive chargers.

What are the most common SMPS problems?

Overheating and/or Ventilation Failures: The most common reasons of an SMPS failure is overheating. Make sure that the ventilation is free from dust and clutter. Also, do not keep the CPU in an enclosed desk.

How do you troubleshoot a power supply?

Power Supply Unit Related Issues and Causes....Note!Plug the PSU power cable into a known working power outlet.Swap the PSU power cable with known working cable.Verify the PSU power cable and internal power adapters are secure connected.Check the PSU for any damage caused by overheating or excessive wear.More items...

When the system is started by switching on the power supply it is called?

Answer: power booting. Explanation: webew7 and 4 more users found this answer helpful.

Why does SMPS fuse keep blowing?

The weak points in SMPS are usually the power devices and electrolytic capacitors. However, capacitors usually fail by drying out, and don't fail short, so a fuse blowing is most likely a bad power device that failed in some way.

How to repair a burnt SMPS circuit?

1) Remove the mosfet from the PCB and check it with a multimeter. 2) Without any doubt you will find the mosfet being the faulty component, so you can quickly go for a replacement of the same using a correctly matched mosfet.

What happens if an inductor burns?

If in a rare event the inductor burns, this would be distinctly visible from the burnt insulation tape which may be also melted and stuck with the winding. An SMPS with a burnt transformer could be virtually irreparable, because a burnt transformer would mean most of the elements burnt out, along with PCB tracks uprooted. ...

Why does a diode burn?

The diode might have burnt due to a high current passage which in turn might have happened due to a stalled mofet inductor operation. Which means that the mosfet might have stopped osculating causing a short circuit through itself, allowing the entire AC to go through the components within the input supply line.

What to do if power supply comes on but crowbars?

If the power supply comes on but immediately crowbars, the first thing to do is check or replace all the filter capacitors on the secondary side of the transformer. Other things can cause this like a leaky rectifier on the secondary or a bad resistor in a current sense circuit, but they are far less common.

Why is the PWM capacitor so small?

Because the PWM oscillator is so fast, the transformer and the filter capacitor on the secondary side can be very small. Although that 2200 šF cap may seem large, if the oscillator is running at 60 kHz, it’s a thousand times as effective as the same value off the 60 Hz line.

What is a kickstart capacitor?

Many power supplies use a “kickstart capacitor” to supply current to start them up. This isn’t shown in the example given above, but it is a fairly common configuration. If the power supply was working, was shut off, but then would not restart at all, replace the kickstart capacitor.

Why use topology converter?

Other topology converters exist and are popular when line isolation isn’t needed, but when you look at what is going on between the AC input and the DC rails on a piece of electronic equipment today, this is the basic topology used because it gives good efficiency and line isolation.

Do transformers need large cores?

Transformers at high frequencies don’t need large cores or many windings for a lot of power, so they can be made tiny and at little cost. The oscillator duty cycle can be adjusted with feedback so that the regulation can be done without losing any power in the process.

Is a high voltage capacitor bad?

The high voltage capacitor (sometimes two capacitors) on the primary supply, which filters the line directly seldom is seen to be failed in the US. However, in Europe where the line voltage is twice as much and where the same multi-input power supplies are used, those capacitors are frequently found to be bad.

Troubleshooting Switching Power Supply

About a year ago, I felt like going bonkers because I couldn’t find the right instructional guide for troubleshooting switching power supply.

How to Fix a Switch Mode Power Supply

Every time a newbie technician asks me how to fix a power supply via Skype, I would always recommend that the person invest in a good quality guide.

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