Got Jacked with Fake Parts - Page 1
Forum section: electronics / general

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: July 04, 2021, 01:45:20 pm
content: I thought it would be instructive to roll my own PWM BLDC motor controller. Started with a random PIC from the bin with no PWM peripheral. I got the carrier solid at 10 KHZ, PW responding nice to input pot, and electronic commutation all working perfectly. Having done that I started on the power side with some IR2101 driver ICs and some FETs. All wired up and driver ICs are behaving strangely. I could not get a high-side pulse and the low side pulse was not only inverted, but responding to both the high and low inputs. All three were performing identically which made me assume I just did something wrong. After several hours of checking and rechecking I concluded that the gate drivers are the problem. I recalled getting them off either Amazon or EBay. I placed a quick order with Digi-Key for new drivers. Upon arrival and replacement, my motor fired right up. I don't know if they were outright fakes or factory rejects, but they looked completely legit. See image below; top real, bottom fake. I've had bad luck with Amazon and EBay in the past and should have learned something. Ironically, the Digi-Key price is usually in line with most others the only difference being that Digi-Key is a bit high on shipping. Live and learn I guess.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 04, 2021, 01:57:48 pm
content: Its not "bad luck" with Ebay/Amazon, it's completely normal and as expected. Just say no, it's always a massive waste of time. Always buy from proper distributors, pricing is the same and the only difference is minimum value for free shipping but that isn'tthatbad if you can accumulate a few projects together or get something you always need in your lab like some missing resistor/capacitor values, connectors/pin headers, wire, solder, etc.

author: Miti
author_rank: Super Contributor
timestamp: July 05, 2021, 02:20:46 am
content: Rub some acetone on them and see how legit the fakes are.

author: BrokenYugo
author_rank: Super Contributor
timestamp: July 05, 2021, 06:48:02 am
content: Only time ebay/amazon/ali chips are worth messing with is if they're old NLA parts or maybe super jellybean stuff, and then expect getting half for free because they're not as described (pulls rather than NOS), remarked lower spec parts, outright inoperable fakes, etc.

author: VK3DRB
author_rank: Super Contributor
timestamp: July 05, 2021, 01:01:08 pm
content: This sort of crap does not only happen through eBay.A manufacturer on the Chinese side was assembling an engineering build of 100 8-layer SMT PCBAs with BGA's, UDFNs, QFNs, 0402s etc for me. No problems with the raw PCB, the component placement or soldering. The build quality was excellent. But they had a problem with the LCD backlight driver chip TPS61160A - a few volts output, rather than around 18V... on every board. These are only 40 cent chips from TI but the manufacturer had apparently procured fakes.There were two critical value resistors on those boards that had to be 0.5% tolerance and I specified Yageo (I haveneverhad a problem with Yageo). It turned out they some were as much as 1.3% out - some high, some low in the same batch. This caused problems, taking a lot of my time debugging the issue. The manufacturer blamed Yageo. Then they said maybe their reflow oven temperature profile was set too high. To feed me suchleads me to suspect they most likely they cheated by using generic resistors than Yageo's quality resistors or they bought fakes - probably the former.

author: wraper
author_rank: Unknown
timestamp: July 05, 2021, 01:06:49 pm
content: Fake IC looks sanded and remarked. There are sharp corners.

author: Warhawk
author_rank: Frequent Contributor
timestamp: July 05, 2021, 01:21:52 pm
content: I saw the title and expected either aliexpress or ebay...

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: July 05, 2021, 08:55:45 pm
content: Quote from: Miti on July 05, 2021, 02:20:46 amI did that first off. Acetone had no effect.

author: wraper
author_rank: Unknown
timestamp: July 05, 2021, 09:04:36 pm
content: Quote from: Ground_Loop on July 05, 2021, 08:55:45 pmChip seems to have rough top surface, so counterfeiters probably omitted blacktopping after sanding and before applying new marking.

author: thm_w
author_rank: Super Contributor
timestamp: July 05, 2021, 09:11:37 pm
content: I just checked and first class mail is $5 from Digikey, not that expensive.I try not to order too many IC's unless I can immediately verify them as functional. Vanxy seems to have NOS/recycled ones for 50c:https://www.aliexpress.com/item/32532756795.htmlbut they aren't consistently good or bad, I've had a few fakes from them before.Anyway, I wouldn't be surprised if there is a more modern version from Digikey that is cheaper or more suited to your needs. If you are doing BLDC, then you'll need three H-bridges. Can probably get something with it all integrated.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: July 05, 2021, 10:54:44 pm
content: Better pics from the microscope. Both are laser etched.Real oneFake one

author: magic
author_rank: Super Contributor
timestamp: July 06, 2021, 01:11:53 pm
content: I was about to say that manufacturer logos are usually sloppy on those things and yours is easy to spot because the vertical bar is too wide, but it's the original part which is wrong here

author: nctnico
author_rank: Super Contributor
timestamp: July 06, 2021, 01:21:22 pm
content: Quote from: magic on July 06, 2021, 01:11:53 pmIn some cases the fake logos & packages are better compared to original. Compare fake FTDI FT232 with original for example.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: July 06, 2021, 03:20:50 pm
content: Quote from: magic on July 06, 2021, 01:11:53 pmThe real one has much better definition than the fake though. The serifs are plainly clear on the 'R' and the logo has better definition.

author: Ranayna
author_rank: Super Contributor
timestamp: July 06, 2021, 06:00:43 pm
content: Hindsight and all, of courseYou can clearly see the grinding lines on the fake.Additionally, the edges of the fake are sharper than on the original, the originals rounding has gone.You can also see that the surface in the dimple and the half circle mark look different.

author: duckduck
author_rank: Frequent Contributor
timestamp: July 06, 2021, 08:43:48 pm
content: Quote from: Ground_Loop on July 04, 2021, 01:45:20 pm"When a check or money order accompanies your order, Digi-Key pays all shipping and insurance (our choice for method of shipping) to all addresses in the U.S. and Canada."https://www.eevblog.com/forum/chat/digi-key-has-changed-and-it-is-not-very-good/msg3273588/#msg3273588