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An Interesting Repair Question

By on August 21, 2009

Got an interesting question today posted by Dennis:

“What is the best fault finding method to find a short circuit in a electronic circuit?”

regards

Dennis J

And here is my answer to him:

Hi Dennis,

There is no best method but there is a procedure. It depends on type of board and type of short circuit. It require different type of meters to locate the short circuit too but generally using ohm meter could find out the short circuit. It can be shorted cap, transistor, flyback, coils, IC and etc or even shorted between the live/neutral to ground. Shorted components in different section in a circuit board will need different method to test it. For example if there is a short circuit  in flyback or yoke coil you need to isolate the problem first by following this link:

http://www.scribd.com/doc/2957819/TT204-Identifying-television-SMPS-problems

Once you have found which section is giving the problem then you can concentrate on checking which shorted components that have pulling down the power supply. If it is a short circuit in power supply side then you may need a light bulb connecting in series along the live line to see if the short circuit still present after replacement of bad parts.

Hope this helps!

Jestine

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2 Comments

  1. jgmanza

    September 26, 2009 at 3:50 am

    Hello Jestine,

    I bought the LCD Monitor Repair book. I am sure I have to read it a few times. Most areas are new to me. Thanks for the detailed section on SMT devices. The actual repair articles are so easily explained. Just one question. Do you have recommendations for which smart tweezers, soldering station, and type of oscilloscope to buy. Can it be an analog oscilloscope of 40 to 60 mhz as recommended in the Testing Components ebook.

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  2. admin

    September 27, 2009 at 5:03 pm

    Hi Jgmanza,

    Thanks. I recommend the advancedevices smart tweezers at http://www.advancedevices.com/

    As for the soldering station there are many spec (wattage) and brand in the market. The one that i can recommend is either Hakko or Goot. You may do more research from the internet about these brand.

    As for the scope-Get a 2 channels 100 mhz analog scope so that in the future you would not need to upgrade anymore unless when you are referring to Digital scope. You may buy from ebay.com or from any local electronics shop that sells used test equipment. The best is to find from local yellow pages and the price range is depends on the brand name.

    Jestine

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