STM32 chip from Ali express

[Tinkertilter]

I recently ordered 5 EVO boards from PCBWAY without the SMT32 chip hoping I could find a good working microcontroller at a good price from Ali Express.

 

The jury is still out, however, I can tell you that you will most likely get a working chip when paying accordingly.

 

I did get 3 working chips, out of 18 chips I ordered from different vendors. 

Not all 18 chips were tested as I do not have the capablity of  testing before installing, every time I get a new chip, I would have to solder it to the EVO board to see if it works -

Of course, I do not want to do this 18 times for a lot of reasons, so what I did instead was, just installed 1 chip out of every order I made to hopefully find a working batch.

 

Here are my findings and experiences:

 

Seller #1

https://www.aliexpress.com/item/10000047602211.html?spm=a2g0o.9042311.0.0.37684c4dJAX0YF

 

This ordered was my first purchase ever from Ali Express. Not anticipating that it would arrive much quicker than what it actually did, I ordered the chips at the same time I ordered the PCBway boards. BIG MISTAKE. The boards took 2 months to arrive whereas these chips took less than 2 weeks. By the time I had the opportunity to test and start a dispute with Ali, it was too late. I also did not know how to navigate the disputes in Ali and this also expired - more to this later on this thread - 

 

I ordered 5 chips from this sellers, costing me $60 USD and none worked. I also lost my refund... these chips came in handy to practice my soldering skills which were good to start with, but I am now 1000% better than what I was at the beginning. Hate to toot my own horn but I am good at this lol

 

 

Seller #2

https://www.aliexpress.com/item/32806426421.html?spm=a2g0o.9042311.0.0.37684c4dJAX0YF

 

I ordered these also at the same time with the Evo boards. To my surprise, all chips worked.

Unfortunately, I had only purchased two chips and to continue with my excellent luck, I managed to damaged 1 of the working chips...this was a the beginning when I was still understanding a few things around here...

 

I have since re-ordered from seller #2 and here is where it gets interesting

The seller cancelled my order telling me she is now out of stock. No problem I get a refund. The following day the chips are back up for sale, but this time, the same chips cost $10 USD more than what they did originally. 

I ordered 5 more  - why not I thought - ... 

 

The 2nd order from Seller #2 arrived and - as per Ali Express request - I tested all 5 chips. Only 1 worked.

Important thing to note is that, these chips did not look like the ones I had originally received from this seller, the chips had different markings and the coding was different.

To my surprise, the markings on these chips, matched those exactly of the chips sold by Seller #1 and Seller #3  - more about this seller next - . 

 

With enough time in my pocket, I am now returning these at no cost for myself and for a full refund.

 

Secondly, and something important to note:  since I've started my refund process, the price of the chips has jumped 120% from this seller -overnight-. I presume this is because this seller is simply reselling someone else's stock and is now offering the most expensive option only - guaranteeing a working chip perhaps? -.

Note: shipping and return shipping was/is all free when dealing with this seller.

 

Seller #3

https://www.aliexpress.com/item/1005003247472878.html?spm=a2g0o.9042311.0.0.37684c4dJAX0YF

 

Do not waste your time here. If you compare this seller against all of the other sellers in the same price range, they all have the same product descriptions.

I can't say 100% but I think some of these sellers are simply reselling somebody else stock and they do not really know if the chips are good or bad.

 

The chips I got from this seller had the same marking and codes like the ones I received from Seller #1 and on the second order from Seller #2.

 

NOTES:

 

I do not know why these chips do not work, however, I know 100% my boards work.

 

I did all my testing with a previously working board (this is why I damaged one of the working chips originally, as I was desoldering it to test another).

With that said, I would like to have a setup that enables me to test a chip before it is soldered, but I do not know what I need and will require help from an electrical engineer that can guide me a little in the process and learn a little more.

I have found this board but I am not sure how I would be using this, nor I know what is needed to connect to a PC:

https://www.aliexpress.com/item/896145045.html?spm=a2g0o.productlist.0.0.6dd145a4PhvTVR&algo_pvid=89f2c3c0-a326-47e0-93e4-ef2c1c14d012&algo_exp_id=89f2c3c0-a326-47e0-93e4-ef2c1c14d012-44&pdp_ext_f={"sku_id"%3A"60822968414"}&pdp_pi=-1%3B105.62%3B-1%3B-1%40salePrice%3BCAD%3Bsearch-mainSearch

 

I would like to have a better set up so when I order a chip - regardless of its origin - I can test wether it is a working chip and if it can be detected in DFU mode before I solder it to the EVO board.

To clarify, soldering and desoldering is not a big issue, the problem is the stress that is put on all components, particularly the microcrontoller. It is VERY hard to desolder without damaging it and of course, the EVO board takes less stress as well.

 

I have still not given up fully on my search, I am contemplating exploring other sellers, however, I am done with the cheap ones as it is proven that they are most likely unknowingly selling bad chips without really knowing. Or perhaps these chips are probably OK in other circumtances or installation scenarios? 

Perhaps all of these might have worked if they had been reset or programmed externally before being programmed? I do not know.

 

Full disclosure in case you did not realize: I am not an electrical engineer nor I am pretending to be one. I simply enjoy learning.

If you can help me learn something new and in the process help others wanting to perhaps do the same thing I am doing, please leave a comment with your thoughts.

 

This is an open thread and any comments are welcomed even if related to orders made from PCBWAY or any other scenario you think it might help me.

 

Thanks 

 

 

Edited January 4, 2022 by Tinkertilter