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The case of the mismarked diodes

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syndy
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re: The case of the mismarked diodes
syndy   2/8/2011 8:10:29 AM
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boblespam
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re: The case of the mismarked diodes
boblespam   2/8/2011 7:45:00 AM
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read "reversed" internal layer

boblespam
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re: The case of the mismarked diodes
boblespam   2/8/2011 7:43:32 AM
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I also had the 7805 regulator syndrome quite a long time ago. But much more recently (last week) I was hit by what could be the "revenge" syndrome. My colleage PCB router handed me the long awaited PCB board that he routed for me. He told me that the SMD components were not soldered because of some organization failure with the external PCB maker (it's always like that when you're late in your projet). I soldered the power supply components and a few other that are critical for the project and needed early testing before the rest of the PCB batch arrives with all components on them (due for end of this week). Didn't work at all. It's strange how my colleages look funny when they come in the lab. AAARGH ! one of the internal layer of the 4-layers PCB was resersed by the PCB maker. You could see it in the usual 1234 little square boxes in one corner of the PCB. But I didn't pay attention to it. The PCB maker had informed my colleague when he receptioned the failing board, but my dear colleague didn't inform me... Maybe because of all the "few" components I asked him to add to the design after he had already routed 90% of it...

Bjarnelof
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re: The case of the mismarked diodes
Bjarnelof   1/25/2011 9:32:41 AM
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The strangest one I've seen was a single 2114 memory normally in a DIL16 that had 4 extra pins like a DIL20, but the plastic was DIL16. For fun we tested it, and if the extra 4 corner pins where ignored, it worked fine.

Stargzer
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re: The case of the mismarked diodes
Stargzer   11/24/2010 11:38:43 PM
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Is it possible that your "unauthorized" vendor somehow got hold of counterfeit parts or even factory rejects from their source?

SmokenMirrors
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re: The case of the mismarked diodes
SmokenMirrors   11/18/2010 4:42:03 PM
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I once remembered we had virtualy 100% failures after a new disk drive design was released to pre-production overseas. Lots of phone calls and emails that week. At the end a very smart hands-on-engineer over there discovered the MOSFETS in an H-Bridge configuration were marked wrong from the supplier and the N and P channels were swapped (both TO-252 surface mount). After that expererience, I learned that suppliers can (very rarely) make mistakes. Up until then, I use to think suppliers never made mistakes, only we did. ...Made for lot's of smoke on every board.

gprabha
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re: The case of the mismarked diodes
gprabha   11/12/2010 3:59:31 AM
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My experience is a recent one with a voltage reference ic ADR03BR IN soic-8 package. When this IC was announced ( 3ppm/c tempco was attractive) by ADI, we had waited for nearly 3 months to get them delivered through our vendor in US (not an authorised agent of ADI). One fine morning, when I started assembling these ICs on the PCB and tested, 1st IC was OK,further assembling on PCBs things did not work. Desoldered and wired with new IC and continue to have this problem. Did not want to spoil the entire day, assembled the IC other way ( pin#1 to pin #5..) and when tested it was OK!!! Wrote this incident to ADI concerned engineer, who straight away disowned responsibility in his/her email as they were not sourced from authorised vendor!. Where is the mistake..? Giving negative feedback is not a good experience....Spoil them with positive feedback?

David Ashton
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re: The case of the mismarked diodes
David Ashton   11/9/2010 12:11:52 PM
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PS good thinking using them for RF coils. Hi-R = good Q!

David Ashton
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re: The case of the mismarked diodes
David Ashton   11/9/2010 10:27:00 AM
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Yeah, been there, done that.... Getting a bit off track now, but in Zimbabwe one could not buy cable ties. So whenever I saw any I used to get a small screwdriver and tease them open so I could re-use them. (Got me some funny looks from visitors for whom they were a dime a hundred...) Anyway, once in a discount shop in London I saw a bag of 1000 cable ties for a pound. I was really chuffed with my bargain till I got them back to Zim and tried to use them. They were supposed to have a little metal springy bit in the head, that gave the ratchet tightening action, and they were missing from all of them. So there was no way they could work and I had to throw them away. With much gnashing of teeth and choice swearwords I might add.....

Robert.Reavis
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re: The case of the mismarked diodes
Robert.Reavis   11/8/2010 6:45:53 PM
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I had an experience with mis-made parts, only it was with the lowly one-watt carbon composition molded resistors. As a high-school experimenter I frequented the local electronic stores and surplus junk stores. One day I spotted a bin of resistors advertised for "a penny a piece." They were painted white-white-blue-silver, gee, 88megohms, I thought they stopped at 20megs. So I got a few and experimented a little, the meter did not even twitch (a real analog Heathkit MM-1, digital had not yet been invented) and the first graduation would have been for 20megohms anyway. So, how do they make an 88meg resistor anyway. Cut one open with the wire cutters and saw nothing, the molded case had no carbon in the center. Grinding one lengthwise to a semicylender showed the same result. Apparently the little length of carbon slurry was not injected into the case and it was just the insulator case and the leads. They had essentially made a non-part. I went back and bought a big scoop and kept them as a conversation piece and as a trick part for the past fifty years. They did make good coil forms for RF work.

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