More bad parts from China

[testian]

Often spare parts which does not fit the manufacturer requirements are sold on ebay for cheap. I usually buy things from aliexpress they have a quite good buyer protection.

[joseph nicholas]

The worst culperts seem to be Chinese capacitors.  I got a batch that looked good until you looked at the bottom.  They all had different design patterns, dirty and some looked broken.  They obviously tried to cover up the poor quality by using clean new plastic wrappers. 

[Codebird]

After an encounter with some 'not-ky diodes' (regular small-signal diodes with a fake label) I've started building an instrument with the express function of measuring components under various conditions to identify counterfeits and defectives. In an amusing irony, all the parts are ordered off of eBay. From China.

[CatalinaWOW]

Buying from known brands does not assure quality, it only makes it more likely.  The big guys are also competing for your dollars and the low price guys are taking their business.  Some of them will naturally slip down a bit on the quality side to compete.  If you could plot quality vs price for all the online retailers and all the distributors and manufacturers the correlation coefficient would be non zero and positive, but you would find not a simple line but a very fuzzy cloud.  If you did the same thing over time you would see the same fuzziness, but the points would be moving around, mostly down and to the left.

[SingedFingers]

The killer for me is unknown spec parts which are rife.

For example if I buy a 1k 0.25W MF resistor from China, what am I getting? Fuck knows.

If I buy a 1K 0.6W MF resistor from RS from TE Connectivity (LR1F series), I'm getting a known 50ppm/oC, over twice the power dissipation in the same package footprint and it'll be delivered by courier the next day for a total of £0.46!

A while ago I had some Chinese MF resistors which were more thermistors. I was wondering why the gain on my amp was shifting slowly and it turned out that the 1k resistor in the feedback network had drifted down to 811 ohms.

[mcinque]

Buying from known brands does not assure quality

It depends. Just for example: buy Panasonic or Nippon Chemicon electrolytics. Buy Vishay resistors. Buy Murata caps. Buy Noble or Bourns potentiometers. Quality is assured. There are companies that sells quality products.
You can bet that if you buy from a reliable connector manufacturer, you'll get the same connectors quality if you place an order every 6 months.

I said "you will get the same quality items for each order you place", while on chinese "no-brand" market you'll get probably different stocks every time you purchase.

[james_s]

The only poor quality resistors I've ever encountered were generic dirt cheap Chinese stuff. Anything from any sort of recognizable brand ought to be decent, it doesn't have to be top notch stuff.