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finding shorted components

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bsco:
Hi there. Just joined this forum.....Have seen lots of Dave's videos an youtube...great stuff...I did a search for this but came up empty so here goes.....I want to build an in-expensive tool for detecting shorted components by following copper traces on the board to lead me to the defective component....example ..ic chip....or chip transistor, etc...Can this be done with a Hall sensor.. or.something that can detect the amount of current flow in a copper trace...I used to use a voltmeter set on millivolts which was connected at the power supply source and then probe along the trace with the other lead at all the solder connections to try and find the component that had the largest voltage drop...just wondering if there was a better way which could be built.....instead of purchased....the above technique does work but is not really effective..neither is it overly accurate...And you always can't depend on the component being overheated to the point so that it can be found by touch...
Cheers,
Bernie

nctnico:
Many decades ago I have used a current detector probe during an internship. In the end the trick with the power supply and the voltmeter works much better. Nowadays a thermal imaging camera may do the trick even better.

rstoer:
When I was a technician we did what you're describing with just an ohmmeter. We'd ground one lead and move the other to different points along the shorted trace. The resistance was measurably lower as you moved toward the shorted component. Like most techniques it didn't always work but it often did.

bsco:
Thanks for your input guys...I guess this technique I was using might be the best way to do this...I never used the ohmmeter test  I used the millivolt test.....by the sounds of it, they serve the same purpose.....
Cheers,
Bernie
P.S. If I find the time I might toy around with using a 50uA meter movement....the magic phase here is "find the time"....I repair all the music equipment for our local music store and they keep me very busy...I have 2 keyboards, a powered PA cabinet and three guitar amps to bring back this week....and a Line 6 Guitar processor.......plus all the musicians that have all kinds of  gear as well....vacuum tube, solid state and micro based.....this keeps me very busy and I get to work from home.....on another note...how do you go about getting notices sent to your email when somebody replies to your post.......

Fraser:
Research 'POLAR Toneohm'

The user manuals contain the schematic and I found them on the POLAR web site usingg teh wayback machine. The manuals are also to be found elsewhere on the net.

Model numbers: 500, 550, 700, 800, 850.

I have the 550, 700 and 850 units and they all work well. They have a built in milliohm meter and a signal injector with inductive signal tracer probe.  They are not that complex and youd build your own using the schematics

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