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Camera Aids Identification of Burned Resistors
Taking a close-up photograph of burned resitors makes it easy to identify the original values.


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Contributed by Puddledud.

The article

 Yesterday I settled to trying to get an analogue  multimeter that I had lying
about the place working. After testing it to find 'da nada' I pulled it apart. The obvious problem
to be found were three fried resistors - goodness knows what else there may be - and I set to
to replace them.

            The 'interesting?' part of the exercise was that I took photographs and then looked at
enlargements on the computer where I was able to call up pictures of the colour codes on the
net and so try to identify the value of the damaged resistors.

            Looking at the picture there are two resistors near a piece of black shield - these
number 1 and 2. There are also two resistors directly underneath a cutout hole in the board -
the damaged one of this pair is 3.

            1. grey, grey, gold, red viz - 8,8 X0.1, 2% to give 8.8 ohms. This one still worked and
registered 8.9 ohms when tested.

            2. white, blue, ?? , red viz 9,6,X??,2% - this one is thought to match the resistor just
above the one labelled 3 and to be of 960 ohms or there abouts. The resistor above the one marked
3 actually tested at 967 ohms.

            3. violet, black, silver, violet viz 4,0,X0.01, 0.1% to give 0.4 ohms

            When I desoldered the resistors one just fell apart, one was still reporting the value
that had been calculated and a third - lying near to one of the damaged resistors - had
enough markings in common with the one which fell apart that it was possible to make a
reasonably reliable conjecture that it had been of the same value - based on the tendency of
circuit designers to reuse values wherever possible.

A section of the photograph of the board, showing the burned resistors is attached.

Regards,

Puddledud





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First posted in November 11, 2011 (111111)

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