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A Science & Engineering OnLine Laboratory Notebook   
This is the laboratory notebook of Damon Bruccoleri.  Here you will find engrossing, thoughtful and fun commentary/opinion.  Leave a comment and let others know what you think about any post here, view my photo gallery, or sign my guestbook.

"...one of the strongest motives that lead men to art and science is escape from everyday life with its painful crudity and hopeless dreariness, from the fetters of one's own ever-shifting desires. A finely tempered nature longs to escape from the personal life into the world of objective perception and thought." - Albert Einstein



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 Thursday, March 27, 2008


How to find a short on a Printed Circuit Board (PCB)   

PCB_complete_sm.jpgWhen I am troubleshooting new PCB's I have a unique technique for finding shorts on PCB's.  I actually have to hand the credit for this technique to a business partner, Dr. Ed Kafrissen.  He came up with a few non-traditional ways of doing business, and this is one of them.

So let me set up a scenario for you, and then show you Ed's solution.  Suppose you have a client and you need to deliver 100 PCB's to him/her quickly.  You have someone stuff the boards for you, now you have to verify they work.  One of the first tests we would do is to apply power to the new PCB and bring the voltage up slowly.  If the power supplies load down, then you got a problem to solve.  You got a short on the PCB.

Damon circa 1982 sm.jpgEd came up with unique solution.  We had this old humongous power supply lying around that was capable of suppling 30v at up to 5 amperes.  This technique only works if the power supply, like ours, has an adjustment to limit the voltage and current.  We would set the voltage to necessary voltage and the current all the way down.  Ed would then hook up the PCB, which immediately loaded down the current limited supply.  He would turn up the current on the supply and feel on the PCB for a hot spot!  Invariably some IC would be stuffed in backwards that our visual inspection did not find, or we would get a PCB which was not completely etched.  In those days we got horrendous PCB's.

Anyway, that was Ed's solution to quickly find shorts on a PCB.  And it worked well as long as you were careful enough to not burn yourself!  Yeow!



damon at 10:56 AM | (4) Comments | Add a comment | Permalink





Commments
Lou said...

That sounds like a great job! On the human side, it would be great too to fix your marriage that brings a bright future. Examining one's action first before jumping into any conclusion proves to be helpful in saving a marriage.

Monday, March 31, 2008 8:53 PM

damon said...

yes Lou. You are as old as the trees and as wise as the running waters. In other words, very wise.

Tuesday, April 01, 2008 8:07 AM

subramaniam shanmugam said...

we use this technique for finding short on the component assembled PCBs which comes for repair.Hot spot components can be identified or bursted.90% of problem solved.

Thursday, January 15, 2009 1:19 PM

hrishkesh said...

i m giving i/p from supply 3.3v,but b,coz of some short circuit or load i m getting 1.23v across the controller

Thursday, January 21, 2010 3:28 AM

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