Mismarked LM34DZ Sensors

Discussion in 'General Electronics Chat' started by tracecom, May 4, 2010.

  1. tracecom

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    I have recently received nine pieces of IC's marked LM34DZ, however five of them read out in Celsius and are apparently actually LM35DZ. The mismarked pieces all bear the NS logo and a date code 01AD, which National Semiconductor says is an erroneous date code. I have offered to send one of the incorrect parts to NS, but don't know if they really want to see it or not.

    In my opinion, the mismarked parts could be knockoffs or they could be the result of an error at NS. Either way, check your LM34DZ parts before you use them. I wasted a fair amount of time troubleshooting a prototype because of this error.

    ETA: Just got an e-mail from the woman I talked to at NS. She provided an address and I'll mail a sample of the mismarked part.
     
  2. beenthere

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  3. eblc1388

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    But you haven't told us where you have got these from so maybe others can be more careful in selecting supplier?

    Ebay seller? Far East supplier?
     
  4. tracecom

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  5. eblc1388

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    I don't believe the manufacturer could have made such a mistake in labeling, not that it is impossible but highly unlikely. These retail shops could have sourced some of their component from the far east.

    In those places, when you request a part, you have the option to tell the shop keeper whether you want the real/genuine one or the working(barely) fake one.

    There can be as much as three times difference in price.

    The most common chips like max232, MC34063, Dallas RTC, LM257x, LM3x, TL431, LM317, 7805, 78L05, 7812.... are the most often faked ones.
     
  6. tracecom

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    I have practically no experience with knockoff electronic parts. When buying parts that ship from the Far East, I just assume that the parts may be copies, but I was naive enough to think that anything I ordered from a company as big as Jameco would be the real deal. National Semiconductor was quick to say that Jameco was not an authorized distributor, and therefore they (NS) would not warranty parts bought from them (Jameco).
     
  7. eblc1388

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    The worst thing is there is often no ways to tell the real from the fake by the look. :mad:

    If the usage volume is large, stress test should be carried out with several samples from the same batch to make sure there is no hidden surprises.
     
  8. retched

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    I remember reading about a coating that fluoresced under a certain wavelength that was used on REAL parts. But after a while, the fakers learned to grind up the real chips and dust theirs with it, so it made identification that much harder.
     
  9. SgtWookie

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    Have you contacted both All Electronics and Jameco and informed them of the problems with the parts?

    What kind of response did you receive from them?

    Counterfeit parts have become a large problem; there is a lot of potential profit to be made from doing such things. Rod Elliot has some samples of counterfeit audio amplifier transistors on his website:
    http://sound.westhost.com/counterfeit.htm
    It is well worth reading.

    The only way you can be reasonably certain to obtain genuine components is to purchase components from factory authorized distributors, or from the manufacturer themselves.
     
  10. tracecom

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    I originally ordered five LM34DZ sensors from Jameco. When I received them, they were all marked as LM34DZ, but three of them performed as LM35DZ. I contacted Jameco, told them the situation, and requested they send me three replacements and that they test them (to be sure they were Fahrenheit) before they sent them. They said they could not test them, so they sent four. Of those four, two are Fahrenheit and two are Celsius, so I now have four F and five C but even though I paid for five F, I am not going to pursue it further at this time.

    When National Semiconductor advises me whether or not the sample I sent them is fake, I will advise Jameco. All Electronics indicates on their website that they have resolved the problem already so I don't plan to contact them.
     
  11. tracecom

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    Interesting read. During the 80's, I made several trips to the Far East during which I learned of the existence of fake watches and designer goods. I did expect that electronic components from the Far East could also be copies, but I hadn't expected that they would be available through reputable US dealers.
     
  12. SgtWookie

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    In the batches you received from Jameco, do the LM34DZ's that perform as LM35's all have the same date code, or are they different?

    I suggest that you don't wait until you've heard back from National Semiconductor. Inform Jameco right away that two in the 2nd batch had the same problem. Otherwise, they will continue to ship the bad parts, and have a much bigger mess to clean up, with a greater number of disappointed customers.

    After all, if someone before you had pointed out this problem, you likely would not be facing this problem yourself.
     
  13. someonesdad

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    I suggest you email Jameco's marketing manager with this info (his name is Greg Harris). His public position is that he's interested in all problems and fixing them. I'd give him the benefit of the doubt -- I've had one or two email exchanges with him and liked what I heard.

    Realize that a company like Jameco is almost a pure marketing organization. Their technical staff is tiny and they are focused on buying and selling stuff. If you report this problem to Greg, it will be interesting to see how they handle it -- the issue is minuscule in actual dollars, but huge in showing a practical and ethical problem. You might also mention that it is getting "coverage" on AAC and interested people are watching.

    If Greg is what I think he is, he'll grab the problem by the horns and force the company to address it. It is complicated and will take time to sort out, but (in some sense) their business name is at stake here. I wouldn't be surprised if he puts the issue into his periodic marketing newsletters he sends out via email.
     
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  14. tracecom

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    Coincidentally, today I received the newsletter from Greg Harris. Somewhat reluctantly, I sent him an e-mail describing the issue. I hope he doesn't take it the wrong way.
     
  15. tracecom

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    Yes, 01AD.
     
  16. retched

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    Well no wonder they dont work.

    If they were made in 1 AD.. Nothing is going to be accurate after Two-thousand-and-nine years on a shelf.

    geez, some people expect everything.

    ;)
     
  17. tracecom

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    I know you are joking, but the NS rep said that 01 corresponded to 2010, but the AD portion was not in their database. And anyway, they do work...just in Celsius. :)
     
  18. SgtWookie

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    I'm betting that those parts with the invalid date code will get pulled from Jameco's shelves within an hour of him reading your note, and that you will get a very nice apology/thank-you reply from him, along with replacement parts shipped to you very quickly at no cost.
     
  19. GregJameco

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    As soon as we heard about this issue we immediately pulled all of the stock in question that was purchased from the same supplier. We've notified this supplier and have begun an internal review. In the event that we confirm that this is a counterfeit product we will increase our Q/A measures with this supplier until we are comfortable that the inventory we are buying is legitimate.

    In the past 35 years Jameco is aware of only a handful of times when we’ve mistakenly purchased counterfeit products and in every instance we’ve taken immediate action to remove the product from supply and take action with our supply channels.

    Greg Harris
    Vice President, Marketing
    Jameco Electronics
    www.Jameco.com
     
  20. retched

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    I still have faith in Jameco, as a company. If they continue to stand behind the products, and make good on any bads, they go up a couple points in my book.

    This is an extremely fast response time. And not only to the buyer, but to the public as well.
     
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