Fake STPS20H100CT? - Page 1
Forum section: electronics / general

author: EU1
author_rank: Regular Contributor
timestamp: July 10, 2016, 07:46:48 pm
content: Does anybody have an idea, is STPS20H100CT on the photo genuine, or just another one China fake?It is suspicious that it is marked with an unusual for ST font and a circle around "e3" is rather an ellipse, but the overall quality of marking is good.

author: Kjelt
author_rank: Super Contributor
timestamp: July 11, 2016, 08:48:07 am
content: Why do you think it is not genuine? Have you had problems?In doubt: check and verify the exact package dimensions in the datasheet.Measure the physical properties that you can verify.It is a relative cheap part €.50 a piece not really interesting to counterfeit but you never know?

author: EU1
author_rank: Regular Contributor
timestamp: July 11, 2016, 11:02:30 am
content: Dimensions are within specs.As for counterfeit low-cost components... Well, I've seen counterfeit LM317, LM393, IRLML2803, and many other cheap components, so I believe that €.50 part may be counterfeit.

author: wraper
author_rank: Unknown
timestamp: July 11, 2016, 11:20:55 am
content: Marking looks fake, however case itself is exactly like genuine TO-220 by ST. Probably they removed paint from different ST part and lasered new marking.QuoteBecause if you source parts in Ukraine, you are fool if thinking that parts you buy are genuine unless proven otherwise.

author: EU1
author_rank: Regular Contributor
timestamp: July 11, 2016, 03:07:15 pm
content: wraper, this part is not remarked. But the fact that the package is looking like a genuine ST TO-220 does not mean that it is genuine.I've seen LM317 from China which were not remarked and their TO-220 was looking exactly like genuine (but marking was looking counterfeit). Destructive analysis shown that their die is about 5 times smaller than the die of an original ST LM317.As for this STPS20H100CT, forward voltage drop is OK. Leakage current at low voltage is OK, I don't have a 100V source by hand to measure it at max reverse voltage. I will measure junction capacitance a bit later.PS: most of components in local Ukrainian stores are genuine (at least in stores where I buy components), it's not China where probably 90% of components are fake or used. Authorized distributors, as well as companies which can process a small order from DigiKey, Farnell, or Mouser with free delivery, are also available, but their prices for small quantities are usually high enough.Also I can order from TME.eu through a mediator with minimal margin (about 3-5%) and free delivery, but I'm not sure if TME stock 100% genuine.But I already have these suspicious STPS20H100CT and most of them are already soldered and attached to heatsinks, that's why I need to know if they are counterfeit before replacing them from already assembled boards.

author: wraper
author_rank: Unknown
timestamp: July 11, 2016, 03:29:18 pm
content: Why do you think it's not? This is one of the most common counterfeiting practices. Take cheaper part, remove the original marking, apply new. For example, most of the counterfeited (rebadged) opamps actually are made by reputable manufacturers, just the part itself usually is multiple times cheaper. IMO they took something with lower voltage and/or current rating and remarked it. The easiest way is to take older datecode parts which had the marking made with paint, as those with lasered marking need to be grinded or blacktopped. They even change markings on NVIDIA and AMD GPUs to "produce" those with marked demand. For example I had received a few fake Toshiba TB6560AHQ which turned out being remarked TA8435H. Of course they looked completely authentic because were made by same company and had exactly the same package. This was the same type of part too, stepper driver. Just pinout is not compatible.

author: wraper
author_rank: Unknown
timestamp: July 11, 2016, 03:46:56 pm
content: Quote from: EU1 on July 11, 2016, 03:07:15 pmIt doesn't need to be 90%, and no one said it is like that. Even 2-5% of fakes is more than enough to not trust any part you buy.

author: EU1
author_rank: Regular Contributor
timestamp: July 12, 2016, 12:25:03 am
content: Quote from: wraper on July 11, 2016, 03:29:18 pmThis diode is neither sanded nor blacktopped: there is no signs of sanding on legs coating and there are no transitions on plastic surface. Mold mark on the top also doesn't look like it would look after sanding or blacktopping. There are no old paint residues.Quote from: wraper on July 11, 2016, 03:46:56 pmDo you mean China sellers from eBay, AliExpress, etc.?I ordered simple parts like LM358/LM317/TL072, and also more expensive and complex parts. Simple parts usually work, but often they don't meet the specifications and usually look differently in comparison with the same parts ordered from an authorized distributor. More complex parts are often remarkedusedgenuine (probably) parts.In my experience 90% of ordered parts were fake or used, and I'm not sure about remaining 10%Probably some sellers on eBay/AliExpress sell genuine parts, but I don't know how to find such a seller, so I decided never again to buy parts from China.Parts from local stores are usually look the same as those ordered from authorized distributors and are within the specs, but not always.I've measured junction capacitance of my STPS20H100CT: 225 pF @ 19V. By the datasheet it should be about 235 pF. So this parameter is OK.

author: EU1
author_rank: Regular Contributor
timestamp: July 12, 2016, 12:35:51 am
content: STPS2045 marked with similar font and with the same ellipse around "e3" in Gigabyte PSU:http://www.hardwaresecrets.com/gigabyte-superb-550p-power-supply-review/5/Hmm... Genuine?

author: george.b
author_rank: Frequent Contributor
timestamp: July 12, 2016, 01:07:08 am
content: I'd test to see if it can take its rated current, can you do that?

author: nctnico
author_rank: Super Contributor
timestamp: July 12, 2016, 01:09:20 am
content: If it where fake I'd expect the tab to be much thinner.

author: Wirehead
author_rank: Regular Contributor
timestamp: July 12, 2016, 06:00:28 am
content: Quote from: nctnico on July 12, 2016, 01:09:20 amNot always a valid statement, there's thin tab TO-220 as well, due to lowered manufacturing costs.

author: Kjelt
author_rank: Super Contributor
timestamp: July 12, 2016, 06:59:43 am
content: Yes the latest ST 78xx regulators are also thin tabbed, so no valid indication if fake or real IMO.

author: wraper
author_rank: Unknown
timestamp: July 12, 2016, 07:34:56 am
content: Quote from: EU1 on July 12, 2016, 12:25:03 amWhy should any residues be there? It's not difficult to remove the paint without any traces. I also have received two kinds of ST M2764AFI UV erasable EPROM from the same seller with 2 week difference. Both had identical date code of year 2008. First had small die which looked like it should be, second multiple times larger. By checking the pics of various EPROMs turned out to be really old AM2764B from early 80s. The first one likely was remarked with faster speed grade IMO.

author: wraper
author_rank: Unknown
timestamp: July 12, 2016, 07:41:29 am
content: Quote from: Wirehead on July 12, 2016, 06:00:28 amExactly opposite, thin tab usually means genuine parts with recent manufacturing date.

author: wraper
author_rank: Unknown
timestamp: July 12, 2016, 07:47:14 am
content: Quote from: EU1 on July 12, 2016, 12:35:51 amThen probably their Philippines factory don't know how to make the marking right, as ST logo is a bit different on the two identical parts on the same heatsink. Font on your part didn't look suspicious to me, weird ST logo was.

author: EU1
author_rank: Regular Contributor
timestamp: July 12, 2016, 12:12:14 pm
content: Quote from: george.b on July 12, 2016, 01:07:08 amSTPS20H100CT is a 2x10A diode, I don't have a low voltage 10A/20A source by hand.But actually voltage drop at few amps is OK, so I have no doubts that it can withstand 2x10A for some time.It would be interesting to apply 2x10A current and measure their parameters after few years, but I don't want to wait few years.Quote from: Kjelt on July 12, 2016, 06:59:43 amST offers L78xx regulators in so called single gauge (with thin pad) and double gauge (normal pad) TO-220 packages.Double gauge regulators have "DG" in part number (e.g. L7805CV - thin-padded crap, L7805CV-DG - usual TO-220 with thick pad).STPS20H100CT diodes are always in double gauge TO-220, so they should have a thick pad.My STPS20H100CT has a thick pad.

author: EU1
author_rank: Regular Contributor
timestamp: July 12, 2016, 02:41:32 pm
content: Quote from: wraper on July 12, 2016, 07:47:14 amAslightlydifferent logo is not a 100% evidence that a part is a counterfeit.I admit that the logo may look slightly differently due to wear of mechanical parts of the laser engraving machine.

author: wraper
author_rank: Unknown
timestamp: July 12, 2016, 03:08:34 pm
content: Quote from: EU1 on July 12, 2016, 02:41:32 pmNot 100% but fakes usually have logo made not very precisely. For example, these are 100% fakes:

author: EU1
author_rank: Regular Contributor
timestamp: July 12, 2016, 04:07:18 pm
content: Another similar diode in Dell H750P-00 Power Supply:OCZ Fatal1ty 700 W Power Supply:

author: EU1
author_rank: Regular Contributor
timestamp: July 12, 2016, 04:35:43 pm
content: Quote from: wraper on July 12, 2016, 07:34:56 amI would say that it is difficult enough to remove every little particle of paint from a plastic package.Quote from: wraper on July 12, 2016, 07:34:56 amI don't really think that they intentionally remarked slow chips. I guess that they had a lot of used 2764 EPROM's salvaged from old boards, and have remarked them to sell as "brand new 100% genuine, blah-blah-blah".You can read their electronic signature to get the original part number.PS: I've seen a batch of 5V relays (used and remarked) and some of them were faulty. After disassembling few faulty relays I realized that they are not actually faulty, but their coil is rated to 9V (or 12V, I don't remember exactly)! China fraudsters are inattentive...

author: wraper
author_rank: Unknown
timestamp: July 12, 2016, 05:02:31 pm
content: Quote from: EU1 on July 12, 2016, 04:35:43 pmThe fact is, 2 different chips han 100% same marking. That means they both were rebadged.QuoteOnly type, not speed grade.QuoteSeen handful of rebadged parts without any trace of old marking ever, what means there is no issue with it. All you need is right solvent.

author: EU1
author_rank: Regular Contributor
timestamp: July 12, 2016, 07:40:19 pm
content: Quote from: wraper on July 12, 2016, 05:02:31 pmCheck with a microscope.

author: wraper
author_rank: Unknown
timestamp: July 12, 2016, 07:46:14 pm
content: Quote from: EU1 on July 12, 2016, 07:40:19 pmI did LOL. I inspect every part which is not from reputable sources.

author: Kjelt
author_rank: Super Contributor
timestamp: July 12, 2016, 08:00:31 pm
content: Quote from: wraper on July 12, 2016, 07:46:14 pmWhat is a reputable source ? Some expensive fake audio powertransistors are everywhere also normally reputable sources.

author: nctnico
author_rank: Super Contributor
timestamp: July 12, 2016, 08:09:02 pm
content: Quote from: Kjelt on July 12, 2016, 06:59:43 amYou don't get it. Thick tabs means lots of expensive metal instead of cheap plastic.

author: Kjelt
author_rank: Super Contributor
timestamp: July 12, 2016, 08:22:37 pm
content: Quote from: nctnico on July 12, 2016, 08:09:02 pmSorry you don't get it, I am not talking about the TO220 vs TO220FP as you suggest, I am talking about the TO220 double gauge (page 36) and TO220 single gauge (page 38) both metal but the one is thicker than the other see for examplethis datasheetfor an ST 7805 and the above mentioned pages.So the thickness of the metal does in no way mean they are fake, because the manufacturer sells both versions.

author: wraper
author_rank: Unknown
timestamp: July 12, 2016, 08:29:18 pm
content: Quote from: Kjelt on July 12, 2016, 08:00:31 pmfarnell, digikey, elfa.

author: Kjelt
author_rank: Super Contributor
timestamp: July 12, 2016, 08:30:30 pm
content: Quote from: wraper on July 12, 2016, 08:29:18 pmI have a good friend in the pro audio repair business that will not get their audio power transistors from them anymore, that's all I am saying

author: wraper
author_rank: Unknown
timestamp: July 12, 2016, 09:11:42 pm
content: Quote from: Kjelt on July 12, 2016, 08:30:30 pmThen your friend should know some more trusty place. Don't mind to tell us which one?

author: wraper
author_rank: Unknown
timestamp: July 12, 2016, 09:20:01 pm
content: BTW, what usually is considered as "audio power transistors" usually are discontinued products. I highly doubt it is even possible to buy them from Farnell or Digikey (unless they are some "lesser" types not beloved by audiofools).

author: EU1
author_rank: Regular Contributor
timestamp: July 12, 2016, 11:07:44 pm
content: Quote from: Kjelt on July 12, 2016, 08:00:31 pmLook more attentivelyBTW, I have several recently purchased (from a local store) 2SC2240 which are not power, but definitely "audio transistors". Looks genuine as for me. The problem with these obsolete Japanese transistors is that they are not available from "reputable distributors".