general circuit testing - how is it done?

Discussion in 'General Electronics Chat' started by multiplex, Feb 23, 2010.

  1. multiplex

    Thread Starter New Member

    Feb 23, 2010
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    Just looking for some insight into the 'repair' sector of electronics.

    occasionally send out PLC components (IO Cards, SBC's, etc) for testing and repair and was wondering what methodology they use for repairing these devices.

    do they have documents from the manufacturers?

    do they go component by component?

    is it magic?
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    There are certain criteria for repairing a board.
    One of them is " is it worth to repair or is replacement cheaper ".
    An other can be the parts are easy to exchange because of holders for the parts.
    (relais are often placed on holders).

    Greetings,
    Bertus
     
  3. multiplex

    Thread Starter New Member

    Feb 23, 2010
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    0
    here are a couple senarios we've been up against.

    one was a single board computer, 386 that ran a LCD panel and user interface. It was made by an italian company that would not offer support. It was replaced for the cost of 1250 euros.

    In a basic attempt to repair the board blindly, i had replaced any socketed chips (rs232 drivers, and some logic components). This attempt failed.

    Second example was a Siemens PLC transducer card. We actually had two of these go in the past few months.

    first card was repaired, but they did not specify exactly what was wrong with it - mentioned water damage.

    second card, they found something bad with a power supply circuit.

    for whatever reason (supply & demand) these components are $2000+ to buy, and often 1000 to repair.

    Being an electrical engineer, i was wondering what type of systematic approach they take to repair. Without some background knowledge, or ways to test the boards it must be next to impossible? impossible, meaning it would take too long.
     
  4. bertus

    Administrator

    Apr 5, 2008
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