BOCHEN WXD3-13 vs 3590S ( Review - comparison) Precision Wirewound Potentiometer

[Kiriakos GR]

For now this topic this is mostly an announcement of upcoming comparison of  BOCHEN vs BOCHEN products differences.

Both low-cost Wire wound Potentiometer they do come from the same source, both are 10 turn (multi-turn) pot .
a) Type 3590S this is advertised as Precision one.
b) Type WXD3-13 this is advertised as regular ten turn pot.

Unfortunately BOCHEN Home page this is a poorly designed website.

It is impossible to do side by side comparison of technical specifications. 
Due the fact that I have an active project this requiring one 10K multi-turn pot, I did order both pots so I to have the chance of one detailed comparison.

Type WXD3-13 seems capable for accepting maintenance, but due my experiences I am aware that when such a pot this goes bad ... Then there is no after life for it 

Back in time BOURNS this was the holly-grail of (multi-turn) pot,  but nowadays for non critical applications I do prefer alternatives.
I am starting to believe that BOURNS Mexico printing has copied so many times in China that now we all using BOCHEN factory products with out us to be aware of it.

[Kiriakos GR]

It looks like that we do not live in to a perfect world.   

3590S which I received this is stamped as Bourns and works great, actually I did use it at my LM317 project

From the other hand, BOCHEN WXD3-13 that I got it is an BOCHEN WXD3-13, at my first test at about 2/3 of inner parts travel I did spot mechanical noise an very specific setting.
While this potentiometer it does work,  this incident of moving parts to scratching it other it did alert me and I asked from the seller for a new replacement.
I am currently waiting for new replacement so to make my mind regarding bellow questions.

a) Did I receive a bad apple ?
b) Are these apples problematic due product design or due poor quality control?

Currently I do assume that in about ten days I will have my answers.

 

[Kiriakos GR]

End of story. 

Second received  BOCHEN WXD3-13 (this send to the seller directly from the factory ) this also have defects, at single travel one direction run this has one issue, at reverse direction in two spots moving parts they are scratching it other.

In conclusion: BOCHEN  factory work this is a bad joke, if you need such potentiometer give your vote to Bourns alternatives.

 

[Kiriakos GR]

I thought to give Bochen a third chance, mostly because of 5% tolerance specification and because similar multi-turn from Vishay and Contelec they are extremely overpriced at retail channels.
Starting from 25 ~ 65 Euros for a single pot this is act of War against consumers. 

My new testing application for BOCHEN WXD3-13 this is for it to work as voltage reference Trim Circuit.
And now I hope to see minor temperature coefficient drift in comparison to 3296 trim-pot clones that you can buy more than ten with a single Euro coin.

Generally speaking I did some extended homework regarding precision potentiometer, in some cases the current this passing from the wiper this should be limited and to follow manufacturer specifications. 
I am currently unaware of 3296 trim-pot and clones Max allowed current this passing from the wiper.
From the other hand BOCHEN WXD3-13 this is a 2W monster and the application of voltage reference Trim Circuit, this is actually a Zero load application for it.

I have just finished my circuit modification, now I am waiting for my air-tight voltage reference circuit to thermally stabilize, soldering heat to equalize with current room temperature that is 27 Celsius.
Two hours later I will perform a final adjustment, then I will monitor over all voltage stability for three days, only then I will be able to say if I am happy or not with the results.   

[xavier60]

I'm having trouble with the cheap 3590S 10K Pots from ebay sellers. After some use, the resistance element goes open circuit.
This is bad when the Pots are used in a bench power supply as the voltage set point will jump from 0V to full reference voltage as the wiper passes over the break. Has anyone had the same type of failure?
I'm now using WXD3-12 10K Pots, hoping that they are better.

[Kiriakos GR]

I'm having trouble with the cheap 3590S 10K Pots from ebay sellers. After some use, the resistance element goes open circuit.
This is bad when the Pots are used in a bench power supply as the voltage set point will jump from 0V to full reference voltage as the wiper passes over the break. Has anyone had the same type of failure?
I'm now using WXD3-12 10K Pots, hoping that they are better.

It would be wise of you to measure the current this feeding (passing) the pot in your application, among with the voltage.
When some one does DIY design the pot watt sizing must be also calculated and the appropriate one Pot to be selected.

WXD3-12 this is 1W  (max operating voltage 160V).

[xavier60]

Over a year of using the Bochen WXD3-12 pots with no open wire type failures. They can go scratchy which I fix with some PAO oil.
In my PSU application the 10K pots are dividing 5V reference for CV and CV settings.
There might be some reliable non Bourns  3590S pots out there but which ones?
Maybe the Bochen 3590S pots are good? http://www.bochen-cn.com/3590.html

[Kiriakos GR]

Maybe the Bochen 3590S pots are good?

You are looking their 2019 build and abandoned since, website.
Non existent links to Facebook and Twitter.
Their FAQ page talks of product warranty with out commitment for a specific time of coverage.
I am unable to demonstrate blind trust to them.

Even so, feel free to test their email,  and nag about the issues that you have.
I am all ears for your own upcoming feedback, of how they will respond back to you .. will they replace at their cost the scratchy ones?

At my Kenwood DC power supply (Made in Japan) that I use often, I did find for it genuine 10 turn Bourns (UK stock).
At my voltage reference, the Bochen still does the job, but it purpose it is to stay unmovable   
     

[xavier60]

I realize that complaining to them is pointless, I would rather fix the problem myself if possible and move on.
I want others to know from my recent experiences that the  "Bochen" branded WXD3-12 pots are proving to be more reliable
than the 3590S pots from ebay and Aliexpress which have unknown origins.
I should have said that by "scratchy" I mean intermittent wiper contact. PSUs can be designed to fail safe with this problem.
A different story when the resistance wire in the pot breaks, sending the PSUs output to full voltage.
There is no passive way to safe guard from this.

[Kiriakos GR]

I realize that complaining to them is pointless, I would rather fix the problem myself if possible and move on.
I want others to know from my recent experiences that the  "Bochen" branded WXD3-12 pots are proving to be more reliable
than the 3590S pots from ebay and Aliexpress which have unknown origins.

They are several significant reasons, that me, an active troubleshooter, I am unable to agree with such low-end Asian factory practices.
"Bochen" logo does not represent a branded solution to me, so to blindly trust.
All Chinese firms does not do any more Quality Control Inspection at the production line, so them to remove the cost of it, and convert it in to profit too.

June of 2021, I did an order of specific Logitech computer accessories, a keyboard and a mouse, two times delivery , two times return back to the shop due poorly working and physically damaged goods.
They did remove at factory Quality Control Inspection too.
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If your complain to them "Bochen" this ended as pointless... this makes them or prove them as liars.

EU market and products distribution chain, this has still a positive side, electronics parts distribution this is made due large and due smaller firms, in other words there is local stock of genuine parts, but you need to make few more phone-calls so to discover of whom haves it, when you need it.

We use to know as acceptable new product fail rate (DOA),  an 3% from the advanced industries even from Japan.
"Bochen" logo seems to have an 45%.
 
In such a Chinese race of whom has 50% of DOA and of whom has 45% of DOA, I am not going to participate as a feedback provider.
The only solution for a hobbyist, this is if you are in need for two good working pots (no-name), then buy ten and use only the working ones.