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Sherlock Ohms

Monitor Goes Dark Over Cheap Components

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Rob Spiegel
User Rank
Blogger
Re: This story is darker than you think
Rob Spiegel   6/19/2012 6:47:00 PM
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Thanks, Nhelmold. That's a good article. Here it is if anyone wants to take a look: http://en.wikipedia.org/wiki/Capacitor_plague

Amclaussen
User Rank
Platinum
Re: Internet for Troubleshooting
Amclaussen   8/28/2012 5:55:56 PM
Good point, Nancy.  Today too many "prestige" manufacturers are no longer taking care of their good name: take for example Panasonic.  It was considered that the very best TV screens available were the famous "Viera" plasma displays by that company.  But, inexplicably, they decided to design their circuitry to intentionally diminish the contrast in several steps, so that the marvelous deep blacks and amazing contrast just went down the drain at "X" hours of use thanks to the on-purpose firmware.  This intentional, "By design" move was probably made in order to make the panels last a given number of hours, but the buyer was actually cheated!  As in your case with your Sony camera, the Panasonic plasmas were pretended to be free from defects, and operating "as designed"... but the owners kept noticing that the rich, deep blacks were turning a dull dark grey instead.  I guess the Class Action Suite is still in the court, and the company still denies anything wrong, and keeps sending defective-by-design products to many unsuspecting customers.   On the theme of counterfeit electronic components, I can attest to the seriousness of the problem: I've seen examples of almost perfect falsifications of large electrolytic capacitors dressed like Hitachi ones, but the initial performance is marginal and with many units open-circuited on delivery. the only way to identify these fakes is by checking the numbers in the official Hitachi catalog, where you can see the "FA" series does not exist in the Hitachi line of capacitors.

But the problem is much more serious when you start finding other components like TO-3 cased power transistors: I've seen and tested several examples of faked Motorola MJ15001 and 15002 power transistors that were in reality repackaged 2N3055 or similar!!!  The fake factory got or implemented a way to imitate the exact appearance of the expensive, heavy duty 15001 by placing inside the can a much lesser, garden variety 2N3055.  At first sight, the transistor looks and tests "good", but will fail miserably at higher currents or breakdown voltage, well under the authentic one specifications.  The same is happening in IC's and many kinds of electronic components, so beware!.  Amclaussen.

failureindesign
User Rank
Gold
Re: No derating?
failureindesign   9/21/2012 5:32:29 PM
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I used to catch grief all the time for refusing to mess with someone else's design until I could find sufficient documentation (like a schematic! and some notes would have been nice) to get some idea of why the original engineer picked the parts he did! 

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