Switch Mode Power Supply Repair And Troubleshooting With The Help Of Dick Smith Flyback Tester.

Smps or switch mode power supply repair and troubleshooting is one of the most exciting circuits for a technician or engineer. It consists of primary and secondary section and has lots of types of components in it to make the power supply work. If any component's in either one of the section found faulty, it may cause the power to blink, no power, power shutdown or low power symptom.

When problems happen in power supply section, an electronic repairer must know how to troubleshoot it. There are many types of power supplies designed by different manufacturers and due to this; it is sometimes quite difficult for us to repair it if you don’t have the schematic or block diagram. Understanding switch mode power supply theory, tutorial or operation will make us better in repairing the unit. In this article, I will show you a way to troubleshoot switch mode power supplies even faster.

A Dick Smith Flyback Tester

Normally when an electronic repairer wants to confirm whether the secondary output diode working or not, he or she must have to desoldered one lead of the diode and test in order to get an accurate reading. Testing diode in circuit usually doesn’t produce accurate result. By using a dick smith flyback tester, you can test the secondary output diodes without lifting the diode from the circuit. The dick smith flyback or lopt tester is very handy and versatile when comes to finding fault locate in the primary and secondary section of a switch mode power supply.

Placing the flyback meter probes to the primay winding of the switch mode power transformers, a good measurement will usually between of 4-8 bars LED lights up. If it indicates only one or two led bars or the flyback tester led goes off (no light), this proof that there are problems in primary side. The primary winding may have a shorted winding or a secondary diode shorted or even the power fet have developed a short circuits. Make sure you have discharge the large filter capacitor and unplug the ac before testing. It is very simple to locate the primary winding of the switch mode power transformer. Connect one probe to the drain (center pin) of the field effect transistor (power mosfet) while the other probe to the positive side of the large filter capacitor. If you carefully trace the drain and the positive pin of the filter capacitor, it will eventually bring you to the two pins of the switch mode power transformer. These two pins is the primary winding of the switch mode power transformer of the equipment.

If you measure a good primary winding and gets 7 bars led, and if you use a long nose plier to purposely short across one of the secondary diode at the secondary section of the power supply, you will see that the 7 bars of the flyback tester led will drop to very low bar (may be one or two bars only) or even the led light goes off. With this simple test, I believe you get the ideas of how this flyback tester works. In other words, if in actual troubleshooting when testing the primary winding of the power supply and the led goes off-suspect one of the diode in the secondary side have shorted. If you get 4- 8 bars (depends on the power supply design) then you have conclude that all the secondary output diodes, smps primary winding, fet and ic are not shorted. With this testing method, it can save you lots of time.

This troubleshooting method also can be use to test the primary winding of a flyback transformer. Sometimes a small secondary diode can go shorted at the secondary section of the flyback transformer (G1 or Vcc supply circuit). It can cause the switch mode power supply to blink, shut down when power on and low output power. It is important to know that all secondary diodes and primary winding are in good condition before proceed to check other components or circuit. Troubleshooting and repairs switch mode power supply can be frustrated if you do not know the right way. If you do not have a flyback tester, make sure you get one and you will be glad of having it. This article only explained one part of the way to repair switch mode power supply, in fact there’s lots more secrets that I’m going to reveal to you. Make sure you have bookmarked my website. You can book mark my website by clicking here.