I agree with what you and the others have said. I should mention, the reason why I want to warn the others about this is because the listings on sites such as Aliexpress/Alibaba actually do say that the component is "original" and "new". If it was marked as refurbished or something like that, I would have never ordered it in the first place. I should also mention that I had many other orders from other sellers for components such as capacitors, resistors, inductors, power ICs, etc...and all of them work 100% fine and came packaged in a sealed reel. I guess it's the microcontrollers that are mostly prone to such scams.
Dana nedjelja, 18. prosinca 2016. u 00:22:01 UTC+1, korisnik nixiebunny napisao je: > > I buy parts from Digikey for this reason. They always work. Think how > much money and time you would have saved by spending more on legitimate > components. > > On 12/17/2016 1:26 PM, Luka C wrote: > > I'm writing this to warn others or ask if anyone had similar > > experiences. I purchased a lot of Atmel ATMEGA328P microcontrollers from > > a seller on Aliexpress. The lot was listed as "new" in the description > > and had a picture of the microcontroller in the reel so I thought it's a > > legit new sealed lot. After the package arrived, I noticed the > > microcontrollers were not in a real and were just randomly taped on a > > piece of some material with some semitransparent tape. I sent the boards > > to the local PCB soldering company and they have soldered > > microcontrollers on the boards. I flashed the program and the first > > board and it worked just fine so I thought I made a great deal because > > the price was really good for the lot. > > > > But this is where things became strange, after I was done programming > > the first board, I tested the other boards. The results were strange to > > say at least. Some of the microcontrollers came in a "state" where any > > fuse reprogramming was impossible (btw, SPIEN was not disabled in the > > fuses!). Two particular microncontroller samples were really strange. > > > > One seemed to execute really strange sequences of commands without any > > reason and my nixie clock would get frozen every now and then. Since I > > own the debugger (Atmel ICE), I decided to debug the firmware on the > > chip. It turns out that the chip would go really crazy when, for > > example, 0 and 5 were displayed on the two middle tubes on my clock. The > > debugger call stack showed that one function was executed when it should > > not have been and the values of variables in the programmed had values > > that in no way could be there in the normal program operation. > > > > Second one had trouble outputting data to the LED controller. Debugging > > this one's firmware showed that the microcontroller was not frozen and > > in fact was sending data to the LED controller but I guess the data was > > not properly formatted or something. > > > > There were some boards with perfectly fine chips so I decided to do a > > simple tested. Since my clock consists of 2 boards, one for the > > microcontrollers and power supply circuitry and the other one for the > > nixie tubes and the LEDs, I decided to do a test and swapped the board > > with the tubes and LEDs across both "working" and "faulty" > > microcontroller boards. The working ones never produced not a single > > fault or glitch, I tried to replicate the bugs on them with no success. > > On the other hand, the faulty ones were impossible to fix even by > > reflashing the microcontrollers multiple times with the exact same hex > > filed used to flash the working ones. > > > > At the end, I am confused. I am not sure what to conclude from this > > really. I believe the fault is not in the board itself (PCB layout or > > connections) but that it comes from the faulty microcontrollers I have > > purchased. After doing a little research on the internet, I found some > > people saying that these Chinese companies basically buy used equipment > > and remove the microcontrollers from them or that they simply purchased > > large quantities of chips that have failed quality control and sells > > them at lower prices. I will try to find a way to remove the faulty ones > > from the boards and replace them with new ones purchased from RS > > Components and then do the tests again. > > > > Anyone ever had similar experiences or has any idea why would this > happen? > > > > > -- > David Forbes, Tucson AZ > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/d1d3cb3b-8fe7-4bdc-bacd-da2d954f0ce6%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
