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How To Use A Scope If There Is No Power In The Equipment?

By on September 1, 2011

I got the question above from one of my members "how to use scope to perform troubleshooting if there is no power in the equipment". My answer to him was to repair the power supply first. Not all repair work have to use scope. Many times using just a normal multimeter could solve a no power symptom. Start by checking the supply voltage to the power ic using voltmeter. If no voltage then suspect either the power ic has shorted or there could be an open circuit in resistors, circuit track or etc. If there is good supply voltage you could either direct replace the power ic or use your scope to check the output waveform. If you are still unsure on how to diagnose a power supply, i suggest that you check all the components in the primary and secondary side. If all the components tested good then direct replace the power IC and retest. This method will usually work but your testing electronics skill have to be good. I’m also assuming you have already check the primary winding with a Ring tester.




  1. Tito Kanshulu

    September 3, 2011 at 3:53 am

    Jestine,thank you for coming up with many solutions on this subject.I am a Malawian here in African continent who is in the same field of electronics and i have found many of your articles very complete. I would love to see me as the best repairer after meeting with you on this page. keep it up.

  2. Amir Mukhtar

    September 3, 2011 at 6:48 am

    A good question from user.
    Actually, i believe and thinked that Oscilloscope uses and more useful in Video, Color, Audio and Synch circuit's problem.

    However, mostly times dead systems is easily repairable with respect to other faults.

    thanks you
    yours student
    Amir Mukhtar

  3. tatekia

    September 3, 2011 at 10:45 am

    please jestine I need a scholarship from you to improve my self

  4. admin

    September 3, 2011 at 9:21 pm

    HI Tito,

    You are welcome.


  5. admin

    September 3, 2011 at 9:24 pm

    HI Tatekia,

    Sorry we do not have scholarship program.


  6. beh

    September 10, 2011 at 4:27 am

    a very good comment dear amir

  7. Md. Shahjahan

    January 1, 2012 at 5:47 pm

    I need SMPS circuit diagram with with description of the ckt commonly used in computer & lcd monitor.

  8. admin

    January 2, 2012 at 9:39 am

    Hi Shahjahan,

    Try find from this link:



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