Cheap Ceramic caps... Grrr

[Aerodyne]

I once used a wholesale organisation - no name, but named after the guy connected with the forty thieves - to purchase a bulk load of electrolytic capacitors from a Chinese source. Very good value for money, on the face of things but (you've guessed it) not one of the many caps were usable. Some we dead short (!) others very low capacitance or apparently no capacitance whatever ( open circuit).
A complaint was ignored, of course. About £60 wasted. Valuable lesson, though.

Ebay is OK provided you take precautions. I very recently bought resistors from an Ebayer but did the research first, when I found that they were based in Hull, with their own website. For those of you actively repairing today's TVs, a visit to their site is interesting:
https://www.mbtvelectronics.co.uk/

With my order, the resistors were exactly as stated - 1W good quality. A minor error in a value sent was immediately corrected. Usual disclaimer: I'm not connected in any way other than as a satisfied customer.

Tony

[ColinTheAmpMan1]

If the Chinese are producing such dodgy electronic components, how come they are managing to have a presence in space research? Surely the number of equipment failures would cause some concern. Test gear that I have purchased from China has been pretty good and usually bought on eBay. Or is it maybe like the old idea that the French don't let the good wine out of the country, so the Chinese don't let the good components out.....?
Colin.

[Maarten]

Originally Posted by ColinTheAmpMan1

If the Chinese are producing such dodgy electronic components, how come they are managing to have a presence in space research? Surely the number of equipment failures would cause some concern. Test gear that I have purchased from China has been pretty good and usually bought on eBay. Or is it maybe like the old idea that the French don't let the good wine out of the country, so the Chinese don't let the good components out.....?
Colin.

I think that's the general idea (in former Eastern Europe it was often the other way around), though it's also an extreme example of 'you get what you pay for', with some unscrupulous faux capitalism thrown in at random for good measure (you pay for it but don't get it anyway).

On the other hand, quality in general seems to be improving, but there's just so many shady traders that the law of large numbers also applies. If you want to rely on Chinese production as a business, you will need some mechanism of quality control and build a relation of trust with preferred suppliers.

[Terry_VK5TM]

Originally Posted by arjoll

In this part of the world, that's the brand Jaycar do - might be useful for Terry as there's probably a store nearby.

I've got a local store (if you can call 200km away local) that is an agent for the Australian Altronics chain and discussion with them has produced a price that is even better than Mouser's providing I buy in a minimum of 500 at a time (and I normally buy common values of components in lots of 1000 anyway).

Closest useful Jaycar is about the same distance away, although there is a closer stockist but their range of components isn't worth mentioning.

[MrBungle]

The Chinese actually produce some of the best quality engineering on the planet to be honest. Considering the state of the country only 50 years ago, it's remarkable. In fact you will find me hitting JLCpcb and LCSC and buying brand new Chinese native brand parts quite regularly for projects. They are just as good and just as reliable as the TI or Linear or Vishay parts and 1/10th of the cost.

However most of our experience here is through consumer channels which, regardless of where you are on the planet, is a bit of a crapshoot. The consumer channels are focused on undercutting the next businessman by a penny on one off quantities and this inevitably leads to a race to the bottom and corners are cut where possible. On top of that there is the clone market where products are cloned poorly to save a few cents which causes reputation to suffer. This is done with good intention but not always intelligence. This causes problems with the signal to noise ratio of good versus bad.

In this circumstance, it makes a nation look pretty bad but they're mostly not. I'd argue that this is a 1% problem which appears large because what we're doing is mostly and edge case. They're huge and generally extremely reliable. Most of the stuff we have these days is stuffed full of parts made there or is entirely made there and it's pretty excellent (assuming we asked them to build to a reasonable price point!). But due to the size there's a few bad eggs in there and hundreds of store fronts who buy stock without even knowing what it is to resell and drop ship. And that's how we end up with cruddy capacitors - going through the consumer doorway.

On point, if we look at LCSC, I've used a LOT (300+) of these and they are excellent capacitors: https://lcsc.com/product-detail/Mult...0V_C46553.html

In conclusion, we're buying stuff from the Chinese equivalent of a car boot sale most of the time. If you got to the major suppliers, it's good all the way.

Edit: just to add, if you think we're any better you'd be wrong on that front. Some of the most expensive worst quality production facilities are in the UK. Someone sent me a picture of a board that was wave soldered and "inspected" a couple of weeks back. It was flooded with solder all over the top and the connectors burned on top. Someone said "screw it" and shoved it in the shipping box.

[Argus25]

Originally Posted by MrBungle

One thing I have found that always works is gold base/leaded transistors. Those are too expensive to bother cloning I reckon! Scored myself a reasonable sized bag of MRF237's the other week. Very happy about that.

That is exactly right. The fakers never use Gold. So any NOS looking semiconductor with gold plated wires will not be a fake.

I got sick of all the dodgy new 7812 regulators, so I got some vintage Motorola ones with 1982 date codes and gold leads. 100% good.

[MrBungle]

I usually buy those new from CPC. £0.22 for ST ones. Seem to be suitably difficult to blow up even if you run them outside the SOA!

The only problem I've had with new ICs is the 34063 switching converters. Had a couple that refused to oscillate at all!

[G6Tanuki]

Originally Posted by MrBungle

In conclusion, we're buying stuff from the Chinese equivalent of a car boot sale most of the time. If you got to the major suppliers, it's good all the way.

Yes, China can deliver the goods when it wants to! [all the Cisco serious-infrastructure-routers I bought for the last decade were made-in-China, presumably with Chinese-sourced components, and we never had one fail through component-quality or poor-assembly/inadequate-testing issues].

Anyone can produce cheap-and-nasty if they want to; if, as noted, you buy cheaply from what amounts to a global tat-bazaar then you're unlikely to end up with top-quality components made in a facility that has internationally-recognised QA-process-accreditation or any sort of traceability.

The worst 'cheap ceramic caps' I ever came across were some pale-green-resin-dipped things, used in a piece of gear that was subject to high vibration in-service, and after a few weeks of "it's fine in the lab but we get odd inconsistent results when we deploy it in the field" they were getting desperate so called me for help. I found that tapping one of these things would generate 25 millivolts of noise. Yes, they were microphonic....

[m0cemdave]

Microphonic ceramic capacitors is a common problem, and not just with parts of indeterminate provenance.

I first discovered it in the late 80's in well-respected pro-audio equipment, and the advent of surface mount has made the problem a lot worse because the pcb's act as lovely sounding boards...

Prime contenders are the capacitors in the feedback loops of audio opamps.

One preamp sounding "a bit muddy" compared with another on a (loud) listening test, with no apparent difference when examined with the test gear and no loudspeakers in the chain, is not necessarily the result of an audiophool's imagination!

[MrBungle]

Yes the cheap "brown discs" are notorious for that. You can actually use one as a mic in one of those old FM bug circuits if you shout at it hard enough!

[Maarten]

Specifying the right ceramic capacitor for the job is a bit of an art.