Counterfeit 2SC2912 (and others)

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If you could show a pic of them I could identify the fake from it.

Here is some pics in case youv have those parts mounted. The first is originals and the other 2 are fakes that are being sold by some suppliers.
 

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homemodder,

thanks, I'll take some pics tonight and post them, but the ones from BDent look exactly like the pic on left...so they should be good.

The ones from MCM do not look like the originals, but they don't look quite like the fakes either.

Anyone know how to read a Sanyo date code?

Thanks to anatech, I'm building up a test jig. I should think about setting up a torture test as well just to be sure that each batch I order will live up to spec.

Funny, but I've bought some small signal types from Fairchild, and they have NEVER measured out of beta spec for me.

I had already covered this beta topic with anatech before. On the datasheet, Sanyo tests that particular transistor at 1A, while the IT-18 has a current of 1 mA. That's quite a difference, but IIRC, anatech said the beta should not vary that much since these are supposed to be fairly linear. The Adcom 535 runs these trannies at about 23 mA quiescent current, so I intend to give that a try first on my test jig and from there increase the amount of current to see how beta behaves. If it is going rapidly up or down, then they are not behaving as specified on their datasheet.
 
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homemodder,

thanks, I'll take some pics tonight and post them, but the ones from BDent look exactly like the pic on left...so they should be good.

The ones from MCM do not look like the originals, but they don't look quite like the fakes either.

Anyone know how to read a Sanyo date code?

Thanks to anatech, I'm building up a test jig. I should think about setting up a torture test as well just to be sure that each batch I order will live up to spec.

Funny, but I've bought some small signal types from Fairchild, and they have NEVER measured out of beta spec for me.

I had already covered this beta topic with anatech before. On the datasheet, Sanyo tests that particular transistor at 1A, while the IT-18 has a current of 1 mA. That's quite a difference, but IIRC, anatech said the beta should not vary that much since these are supposed to be fairly linear. The Adcom 535 runs these trannies at about 23 mA quiescent current, so I intend to give that a try first on my test jig and from there increase the amount of current to see how beta behaves. If it is going rapidly up or down, then they are not behaving as specified on their datasheet.

Look at the folowing pic, this is how good fakes can look, these were supplied by german supplier and the pic they sent me of a sample, the stock supplied to me resembled the pic 100 percent. I was still a bit suspicious so I sent them off for sanyo to inspect, fake was the reply. The 2nd pic is of originals in a rotel amp.

Here in my country 90 percent of transistors are fakes, this industry is in a mess. Companies making these fakes are getting very good indeed where the fake part is virtually undistinguisable visually from the originals.
 

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Hi sonidos,
Thank you. :)
I have compared transistors measured on a jig where I read off the values for Ib and Ie directly and calculated the Beta. They (surprisingly) agreed pretty closely with what I got from the IT-18. This was an unexpected result, but hey? The answers are correct and who am I to complain? I have measured several different types of power and signal transistors, they all measure the same using either method, within experimental error. It's easy enough for anyone to whip up a testing jig for checking your meter, a sanity check at the least. Me? I trust my IT-18 to give me answers within the ball park. Exact figures don't really exist unless you can fix the die temperature and related currents and voltages. So, don't get too freaked out about numeric gain figures. The signal transistor matching jig (and it would work equally well for power devices) is a ratio-metric type test. All it tells you is that two transistors are matched in conductance at the test point. You can easily vary the collector (drain) voltages, as well as the tail (test) current. Remember that beta will be a variable within limits and accept that.

You will find that the beta operates on a gentle curve compared to emitter current. Collector voltage will also affect the beta (Early effect). If you see a jump in the value, you either have a bad connection or a bad transistor. I have culled a few transistors like that using the IT-18 and heat / cold.

Another technique to explore is to measure the base-emitter, or base-collector capacitances for certified "real" parts. You might want to do that from time to time and for each manufacturer. Then read your suspect devices. A fake will probably have a value that is substantially different from your base line readings. You are actually measuring the size of the die in a round about way. There are other factors that can affect the absolute value of capacitance. A fake would normally measure lower capacitance (surprised?).

Once you have done that, you can compare your readings with other people. I think we took some readings back in a thread I started a few years ago. Something like "My transistors, real or fake". I could be mistaken on that a bit. There is some good info in that thread, and there is really no point in repeating it here.

-Chris
 
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Great pointers

Chris - sounds good. And thanks for pointing out there is already valuable info on the forum. I'll give it a good read.

Yep, I've even thought about putting the jig in the center of styrofoam box. I inherited a cool Fluke temp sensor that I could insert into the box so as to take a temp reading before testing a set of transistors. I would hate to test a set at 30 celsius and another batch at 22 celsius. In Texas, we have big temp swings, even during the day in our homes.

I know about the curve in the beta after studying the Sanyo datasheets. That's why I still have my doubts because the Sanyo ds's go down to about 100 ma. So I know it can look like a broad curve and they did not measure that down low. I'll see. I'm hoping to have the jig running by next weekend.

So for us hobbyists that buy a few transistors at a time, what do distributors do if you call them up and tell them the parts you bought aren't living up to spec? Do they laugh and tell you to order more if not happy with beta? Or if you call them on it, do they send another batch? I guess I am about to find out.
 
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looks real!

Homemodder, that last pic does look like the real thing!

I caught a documentary recently on PBS (Frontline?) that discussed the explosion of fakes across the world. I remember when Blackhawk helicopters were crashing due to fake bolts on the rotors. And they said the probably has gotten significantly worse.
 
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Hi sonidos,
Forget about actual numbers. You are more interested in gain ranges and what parts match each other. Once matched, tie the parts together.

If you want to control the temperature aspect, the best way will be to use a heat sink with a thermostat temperature control. For you, run the parts up to about 35 °C and make your beta measurements. That insures you can recreate the same conditions year round. Making stuff hot is easier than cooling it off. Signal transistors can be inserted into holes with the leads sticking out. Drill a series and you're all set for TO-92 parts. Flat surfaces to mount other power devices should cover just about anything else you need to play with. Remember to keep things simple, that stuff works better.

Low current beta readings are not guarantied, the devices are expected to run at higher power levels. Don't worry because all common output designs run at low currents in idle. So, if they don't show the curves below a certain point, you can't hold them to it -yes? Don't worry about this.

Defective parts are something any distributor wants to know about. By the same token, that distributor also needs to know you know what you are doing, and are measuring the parts properly. One of the reasons I bought expensive test equipment was to shut that argument down before it got rolling. That's really a side benefit for the main seasons I bought that stuff to be honest with you. Otherwise, you must construct their test jig (At the manufacturer) as they built it, using equivalent test equipment and procedures, or they can't take you seriously. You don't want to force them to check their own product for defects and find out that you are the one who was in error. Their jigs are normally really simple, they don't cost a lot to build. So put a few together and become familiar with them. Keep in mind that a Radio Shack meter will not be acceptable. However, something like an HP 3478A or 3468A (in tolerance) will probably be more than acceptable for DC readings. They used those same meters (and may still do), so they can't complain about inaccurate readings.

If you want to challenge the big boys, you must be able to convince them that your values are reasonably accurate and have the probability of being correct, a high confidence level if you will. This is not unfair at all. Believe me that On Semi, Fairchild or anyone else are not in the business of selling junk. People who sell budget or replacement brands are another kettle of fish, but you must also be able to convince them that your numbers are accurate. Otherwise you will be ignored, and rightly so.

As for fakes infiltrating every parts depot in every industry, yes. Where there is a buck, you will have people who chase that buck with a very low standard of morales. One reason is that the average human is lazy to the point of neglect. Even if parts are supposed to be validated, you will find some people who will sign off without performing the work they are signing for. It's a human condition, and the reason why fakes are such a problem.

The root cause is a society thing, and that goes back to each parent. Sad but true, out society is in decline. "Me first" and disrespect are the defects of character that are the root of most major issues - including wars. You want to change this? It starts with how you bring up your children.

-Chris
 
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More good stuff to save on my hard drive

Thanks Chris. In my previous job working in testing hardware, we made use of an FPGA that suddenly stopped working in our product. We got into a battle with the manufacturer because we thought counterfeit because the silkscreening was slightly different. they finally divulged the date coding scheme. Turns out that they ran out of stock from their fab in Japan and started supplying us with parts from their Taiwan fab. They took back the bad ones (we had to promise on a stack of bibles that we did not desolder them from our boards) and they replaced them with ones from their Japan fab. Problem solved. But it took one heck of a fight. So as a little guy with a little squeaky voice, at least I have plenty trannies to play with in my tool box now.

I'll do some more reading in the forum and I won't get wound up on beta numbers, I hear what you're saying. I just thought that I would get good matches on my complementary pairs and I'm blind on how good is good enough. When I received NPNs with 65 and PNPs with 150, it seemed pretty disappointing. IIRC, you said I should try to get as close of a match as I can on these complementary pairs. I guess I'll just shoot for my best pairings and then see how my amp performs. At minimum, all have really tight matching between my 2 NPNs and my 2 PNPs on each bank.
 
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Hi sonidos,
Well, actually you are better off when you can match the PNPs and NPNs. Measured and proved.

So, what do you do? Well, NPN and PNP devices are different on a basic level (Mosfets more so). So accept that. Some complimentary type numbers are better than others at matching NPN and PNP devices. I had commented many times at how nice the On Semi MJW0281 and MJW0302 parts were. They were extremely consistent, and NPN and PNP types were also close matches. They were so close that you could easily use them without selecting and get better matches than carefully screened almost anything else.

About the only thing you can do is research parts until you get a handle on which match and how they perform. Then, buy those for replacement purposes, and especially for new design. The same goes for your more complex ICs, some will have high power leakage and run slower, but be rated for the more desirable higher speeds (sound familiar?). You get to know the people in the industry, and more importantly the corporate personalities involved. Companies don't change their corporate personalities very much over time. That means you know who to deal with, and who is best left alone.

I just found a 256 MB PC133 memory SIMM that was causing trouble. Runs fine at 100 MHz. The label looked cheap, which is why I tried it in a different machine instead of throwing it out. My suspicions were confirmed. You can tell a lot from simply looking at things some times too, as you know.

-Chris
 
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Chris, you are saving me tons of sweat, time, and grief. :)

As luck would have it, I did a search on the forum and found a 6 year old thread from someone complaining about PNPs measuring much higher for hfe than his NPNs on his stock Adcom. Another user reported that he had seen this characteristic on many types of Adcoms and as much as 100% higher over the NPNs. Nelson even speculated on this, but it was just a quick comment that it was done intentionally by Adcom. So maybe this is just what to expect out of Sanyo and if I get a good NPN/PNP match, then leave happy knowing that I'm close.

Sorry folks - no more interruptions from me other than to display photos of what I have on hand as it relates to this thread.
 
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Sonidos if you really want to get beta matched pairs I suggest you contact a Rotel service dealer, tell them you have a rotel with blown output pair, theyll supply factory matched pairs, Ive done this plenty times. You might just have to get a seial numer from someone that has a rotel amp, the basic models all use this pair. When you purchase sanyo direct and ask for pairs they supply pairs that are matched within 3 percent, Ive never purchased direct this particular pair but thousands of to220 and to92 which were excellently matched.
 
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Hi homemodder,
if you really want to get beta matched pairs I suggest you contact a Rotel service dealer
That's rare and unheard of these days. The only company I can recall doing this (and the parts really were matched) was Marantz in the early days. There were others that matched gain with coloured paint dots too.

When we requested matched pairs (and I convinced the company we were serious about this), we were generally sent a bunch and told to match them ourselves. I'm more comfortable doing it that way anyhow, I know what we are installing for sure then. Adcom didn't need convincing, they just sent us a bunch to match ourselves.

Certain part types do match well. The 2SD424 and 2SB554 weren't too bad. Better than the MJ15015 and MJ15016 garbage (hFE commonly 55 vs 200). MJ15024 and MJ15025 matched far closer, but then again, they were not economy devices. I often found the average shops using junk like the MJ15015 types, because they were rated similarly to the much, much better MJ15024 types. They thought these devices were actually the same part!

Nelson even speculated on this, but it was just a quick comment that it was done intentionally by Adcom.
Really? I'm not going to dispute this, but I worked with Adcom for years and never ran into this type of thing. It was certainly never mentioned to me either, and you think they would have since we were rebuilding amplifiers. To the best of my knowledge, the intent was for both polarities to be matched for hFE. Mosfets would be a different animal though. It is possible that comment was related to Mosfets, rather than BJTs?

Hi sonidos,
you are saving me tons of sweat, time, and grief.
Cool! I'm glad about that. :cool:

-Chris
 
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Chris -

Thanks for responding...informative as usual! Also thanks to Homemodder for the suggestions.

I'm leaving now for Houston to help udailey with kitting the MyRefs. I've done this in my previous life at a computer manufacturer.

I will relocate that thread and link to Nelson's comment directly. Sometimes being a noob, I get confused re. the intent of someone's comments and I don't want to lead anyone astray.
 
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Hi sonidos,
No worries there. As I said, I don't know who said what, or to what the statement(s) may apply to. I really wouldn't worry about this too much. Remember, what I said was that this advice was not something I had heard from my usual sources, or from the manufacturer either. Nelson did (I believe) design the prototypes, and they were developed (changed) a bit further by the engineering staff at Adcom. At this point in time, I don't think there are any original employees left with the firm. Adcom was sold and relocated to a more southern state.

My only point is that a deliberate mis-match between the NPN and PNP devices does not make any sense to me. However, that doesn't mean that this is not true, or for what reason it may have been done.

-Chris
 
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Chris -

I'll keep this short so this thread doesn't get derailed by my beta questions.

I understand you and agree that a discussion on Adcom's decisions on their amps is pretty fruitless. And how many people have been hurt by finding a great match on their replacement transistors? Probably not one person. Yep, the objective is to make sure you have good parts (not counterfeit), then test them thoroughly, correctly, and efficiently for a good match so that the end result is a great listening experience. So once I get testing, if I have what I think are fakes, I'll be sure to contact the distributors and then let folks here know if I have true problems with fakes. Again, thanks for keeping me on the right road.
 
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Hi sonidos,
Don;t forget that with DIY, you have the opportunity to do fine tuning. You can do those little jobs that the factory can not afford to do. These jobs will result in a more stable amplifier, and one that should sound better as well.

This stuff is on target for this discussion as well.

-Chris
 
You guys should get a good laugh out of this. I bought 5 of these for $15 from an ebay seller well before I started my Adcom repair. I promptly forgot about them until I was cleaning up the bench and putting stuff away.

I didn't have to look very hard to determine they were likely fake. See if you can see what tipped me off. <grin>

Apparently, sometimes you don't have to saw a TR open to see if it's fake. I'll open one anyway out of curiosity and post a pic here when I do.
 

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I don't know what you're talking about fredlf, but I had some great Janpanese food tonight. :D

Chris - yeah, I'm having too much fun and this fine-turning should eventually put a big smile on my face. I'm going to check the capacitance on these bad boys and see what I get.
 
I just bought some 2SA1492's from audiolab.com and boy they sure look suspect. not at all like the old parts that came out. the date code is completely different and the printing is different. I will try and get some photos posted tomorrow. I sure would like to know how to read the dates codes as well.


Zc
 
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