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Resistor Fun

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SOFTengCOMPelec said:
In that case, (presumably) it is a VERY rare, faulty or mis-labeled component. Assuming the meter has read the resistor value correctly.

I believe there is a 499 Ohms value version, which this may have got mixed up with on the production line, by mistake or something.

Or they could even be (VERY rare) fakes, which have entered the (apparently genuine) supply chain ?

If you are worried, you could try contacting mouser ?
(But best to confirm with another multimeter and/or use a known resistor value and check it reads about the correct value, first).
Click to expand...

That is very possible, it can also be counterfeit. Not even from Vishay. Maybe bought through a broker.

I remember a customer we have at work, ordered a set of ceramic capacitors which seem to be made by Murata for a design that was going into production. These capacitors of course failed after some time because of over voltage stress. When the part number was send to Murata, it turned out that this specific model did not exist, not at that rated voltage, only at lower voltages. The stickers on the reel had been replaced with fake stickers mentioning a higher rated voltage.
 
Dave Jones on EEVblog did a series of articles about this.

He had bought some reels of ultra-precision resistors from digikey for a production run of some measuring instruments. They were supposedly 0.1% or 0.01% resistors, but they were way off, like 10%. So, this sort of issue does exist. It's not clear whether these were fakes or simply a duff batch. However, digikey weren't interested, and didn't even respond to Dave's e-mails to ask for replacements.
 
Some speciality resistors don't, but standard ones typically do. Some of the super precision ones are actually pretty impressive, basically a flat glass or similar material with really thin metal (copper I think?) film and it goes in various zig zag patterns then they trim it with a laser.
 
Yeah, it's a little disconcerting, but isn't that exactly why you were testing the brand new resistors in the first place? Not just to find any that were out of spec (which itself would be a little surprising with quality parts), but to find mislabeled parts.
 
Carson Dyle said:
Yeah, it's a little disconcerting, but isn't that exactly why you were testing the brand new resistors in the first place? Not just to find any that were out of spec (which itself would be a little surprising with quality parts), but to find mislabeled parts.
Click to expand...

Never expected to find mislabeled parts, because I'd never seen it from Vishay (via Mouser). I did it to match the resistors of the left and right channels of a headphone amp that I'm about to build.
 
William Gaatjes said:
That is very possible, it can also be counterfeit. Not even from Vishay. Maybe bought through a broker.

I remember a customer we have at work, ordered a set of ceramic capacitors which seem to be made by Murata for a design that was going into production. These capacitors of course failed after some time because of over voltage stress. When the part number was send to Murata, it turned out that this specific model did not exist, not at that rated voltage, only at lower voltages. The stickers on the reel had been replaced with fake stickers mentioning a higher rated voltage.
Click to expand...

Yes, fakes and dodgy items, seem to be an ever increasing problem these days. With Chinese manufactured/purchased items, often connected to it. Ebay has become a risky place to buy electronics components from.


Mark R said:
Dave Jones on EEVblog did a series of articles about this.

He had bought some reels of ultra-precision resistors from digikey for a production run of some measuring instruments. They were supposedly 0.1% or 0.01% resistors, but they were way off, like 10%. So, this sort of issue does exist. It's not clear whether these were fakes or simply a duff batch. However, digikey weren't interested, and didn't even respond to Dave's e-mails to ask for replacements.
Click to expand...

The video you are refering to, seems to be this one: (EEVblog #133 - Dodgy Digikey Components)

https://www.youtube.com/watch?v=QvyHNVQZcHw

The forum link about it, is here:
http://www.eevblog.com/forum/blog/eevblog-133-dodgy-digikey-components/

It seems the resistor manufacturer, may have been responsible, and was willing/keen to sort it out. E.g. They wanted samples of the faulty parts and hardware units (produced).
I can't see what the later/final outcome was, eventually.
But Dave mentions something about Digikey finding other reels of out of spec, resistors at Digikey.
 
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