Fake Bourns 10 Turn Potentiometer Tested to Failure - Page 1
Forum section: electronics / general

author: samsam11
author_rank: Newbie
timestamp: March 09, 2020, 09:01:16 am
content: I bought the least expensive (under $2) 10K 10 turn potentiometers on AliExpress. Wanting to see how long it would last I rotated it full scale idley for a few months while doing other things, it takes around 5 seconds to turn it 10 times, so with the spec on the real ones being 1,000,000 360 degree rotations it would take 138.8 hours of full time twiddling to get to that, I was not counting but 250,000 or so rotations would not be unreasonable. The failure mode was the wire breaking or the wiper breaking, one may have caused the other and I can't be sure which one came first, a brass colored metallic powder was contained in the lubrication.In my very basic testing at about half way they remained quite linear, but the feel did worsen.They don't hold up to the real ones, but for the price I was not expecting them to, I would not use them on anything that gets daily use or near their 2W power rating.

author: Berni
author_rank: Super Contributor
timestamp: March 09, 2020, 10:29:34 am
content: If they survive 250k cycles that's still not bad, especially for the price.What is the test jig used to exercise them?

author: exe
author_rank: Unknown
timestamp: March 09, 2020, 10:35:12 am
content: Sorry, I didn't get the results. How many rotations did they survive? How many samples did you try? Did you rotate manually?My experience: I bought several different species from aliexpress, some of them feel fine, butone of them fall apart in my hands(could be fixed with glue, but the shaft was bent too, so I just threw it away). I'd say they are usable for light usage. Since quality varies a lot, I wouldn't use it for a mission-critical system. On the other hand, for a mission-critical system I'd use a DAC or something to control parameters, not a mechanical device.On my psu I have four of 10-turns pots (two channels, each with CC and CV knobs). So far the most expensive (presumably original Bourns part that I bought for $15-17) feels the best. Rest (including original parts from a different manufacturer, but I don't remember the brand, it cost $11-14) works much worse. Devices from aliexpress are OK. I've been using my power supply for like three years. The usage is relatively light.

author: samsam11
author_rank: Newbie
timestamp: March 09, 2020, 11:00:12 am
content: I did not use a jig, I just turned it while I was doing things that did not need two hands. It has been around 3 months since I got them, and I did a rough estimate based on how long it takes me to spin it 10 turns (around 5 seconds) so in an hour I could do 720 3600 degree rotations, as Bourns rates lifespan by shaft revolutions that is 7200 cycles by the metric Bourns uses. So 250,000 would take 34.7 hours, around 30 minutes a day.This may very well be quite off, but even plus minus 100,000 cycles it gives a reasonable idea of lifespan. This was only tested on one sample, I don't have that much free time.

author: rs20
author_rank: Super Contributor
timestamp: March 09, 2020, 11:52:04 am
content: Hmm, not sure I trust this reasoning. The rate at which you turn the pot while attentively timing it is possibly very different to the rate when you're multitasking, and who knows how often you took little breaks without realising. Why not write a simple arduino sketch to measure sweeps of the value via the ADC next time? Would've been about 20 lines of code tops and would have removed all doubt.

author: HighVoltage
author_rank: Super Contributor
timestamp: March 09, 2020, 11:56:35 am
content: Just yesterday I had to replace one of these low cost 10k types after one year of little but regular usage in a high voltage power supply. This time I took a genuine Vishay type.

author: samsam11
author_rank: Newbie
timestamp: March 09, 2020, 12:14:38 pm
content: I know it's not at all accurate, the only concrete conclusion that should be taken is that they do not match up to the lifespan of the originals and that they can last an OK number of cycles.The Arduino thing is a great idea, I think I will order some new ones and get started on that.

author: thm_w
author_rank: Super Contributor
timestamp: March 09, 2020, 11:17:07 pm
content: LCSC has some Bochens anywhere from $1 to $5https://lcsc.com/product-detail/Potentiometers-Variable-Resistors_BOCHEN-Chengdu-Guosheng-Tech-WXD3-13-2W-47K_C127114.htmlhttps://lcsc.com/product-detail/Potentiometers-Variable-Resistors_BOCHEN-Chengdu-Guosheng-Tech-7286-2K_C127161.htmlThey are at least genuine articles.If you need funds for testing or equipment I can throw in some dollars.

author: amyk
author_rank: Super Contributor
timestamp: March 10, 2020, 02:21:07 am
content: The most amusing thing about the fakes is the name: I've seen BAORES, BONENS, BOORES, BAOSHI, BAOTER, and even BONERS...

author: Refrigerator
author_rank: Super Contributor
timestamp: March 10, 2020, 07:37:23 pm
content: Quote from: amyk on March 10, 2020, 02:21:07 amLooks like BOURNS have some stiff competition

author: Nusa
author_rank: Super Contributor
timestamp: March 10, 2020, 08:40:09 pm
content: Replace yourself in the shaft-twiddling business...use a small stepper motor to turn the shaft at a human-like rate.

author: xavier60
author_rank: Super Contributor
timestamp: June 14, 2020, 09:32:20 am
content: I had 3 of these fake Bourns 10 turn pots fail each with about 1 month's worth of heavy use as controls on a bench supply.When the resistance wire breaks, the pot behaves like a switch, no reference voltage when the wiper is below the break and full reference voltage when the wiper is moved above the break.This causes the PSUs output to jump from 0V to the full 30V without any warning, nasty!So far I have had no failures with the Bochen(WXD3-13-2W) 10 turn pots.I also added protection to detect abrupt increases in wiper voltage.

author: Nominal Animal
author_rank: Super Contributor
timestamp: June 14, 2020, 06:08:53 pm
content: A testbench with a bunch of 28BYJ-48 geared steppers with 3D-printed "shafts" for turning the pots, each pot configured in a voltage divider configuration with output to the controlling microcontroller ADC, and you could keep track of the linearity and turning noise as well. These steppers can run from 5V using a trivial ULN2003 unipolar driver, and are unlikely to lose any steps in this scenario.It'd be an interesting quick project for someone needing to test a bunch of pots. Me, I prefer to use encoders instead; I just like them more.

author: Refrigerator
author_rank: Super Contributor
timestamp: June 14, 2020, 08:14:53 pm
content: Quote from: Nominal Animal on June 14, 2020, 06:08:53 pm28BYJ-48 steppers are pretty slow, for something like this just about any stepper would work.

author: Nominal Animal
author_rank: Super Contributor
timestamp: June 14, 2020, 09:49:16 pm
content: Quote from: Refrigerator on June 14, 2020, 08:14:53 pmSure, but the 28BYJ-48 are cheap (~ 15€ for a dozen), low-power, and ubiquitous. If you use a 32-bit microcontroller, you can pulse them fast enough to mimic human finger turning, methinks.

author: Seekonk
author_rank: Super Contributor
timestamp: June 15, 2020, 04:58:11 pm
content: The ones I got barely had any threads. Just getting the nut on was time consuming and without a lot of goop the nut won't stay in place. I did have one open up on one end. Found it funny they were trying to copy a Made In Mexico product.

author: dag777
author_rank: Newbie
timestamp: December 02, 2022, 09:56:11 pm
content: I realize it’s an old thread, but I wanted to warn anybody who may see this post: even pots sold by Amazon themselves (not by a third party seller) are counterfeit. I just got one, and though it looks good at first glance, it is obvious it is made of pure chinesium once you look for the signs.I ordered the same part from mouser, you can absolutely tell the difference.Buyer beware.

author: nukie
author_rank: Frequent Contributor
timestamp: December 13, 2022, 03:38:38 am
content: From my previous research, you should worry more about drift at different temperatures. For eg, 5C vs 60C. You will see what I mean when you see the 'jump'. Not worth at all.

author: Berni
author_rank: Super Contributor
timestamp: December 13, 2022, 06:15:57 am
content: At one point i also bought new potentiometers for the analog stick of an xbox controller.They said "Alps" on them and looked pretty close. They worked fine, but then started to die after only a few months. So i clearly got fake ones.Watch out for buying Alps brand stuff from the gray market.