In the meantime, someone informed me that these are Chinese MJ15022/23 transistors, manufacturer is INCHANGE SEMICONDUCTORS, so nothing of the sort. I don't take it.
Hi Nixie62.
I tell you for sure that it is not the manufacturer Inchange Semiconductors.
Their logo is: "isc" and not the one on your transistors.
The "isc" produces good copies of transistors no longer in production. Especially those of Japanese origin.
I have 2sc2238 and 2sa968 transistors from "isc" and they are very close to the Toshiba originals.
HI.
I tell you for sure that it is not the manufacturer Inchange Semiconductors.
Their logo is: "isc" and not the one on your transistors.
The "isc" produces good copies of transistors no longer in production. Especially those of Japanese origin.
I have 2sc2238 and 2sa968 transistors from "isc" and they are very close to the Toshiba originals.
HI.
It is possible, I am poorly informed. So I was told, who knows what it is. Seen others with that logo on ebay, but I don't know what's inside and who makes them. Maybe it's good, maybe it's not. Real fakes of these transistors are always ON or Motorola.
All I know is that old numbers with new manufacture are fakes. They do not behave like the originals. Whether they blow or not isn't the only factor in a good second source. I would hesitate to use the word "copy", because they aren't. They are at best, "like". Make no mistake, they are a different part but sport the wrong part number. In other words, a fake.
Yes, I know that. Only for these particular ones it seems that no one knows who the manufacturer is. And that's saying something, too.
The fact that they are not known bad at least gives them a chance of being “good”. I would test SOA before using in any application where it needs to be that “good”. It’s not that hard to do - just a DC operational test at 2.25A, 80V for a second or two. You’ll find out in that second or two, although it takes all afternoon to set up if you don’t already have a jig.
No, they are not ISC for sure. ISC (or these guys whoever they are) might make a passable MJ15022 - they are not that hard to make these days. Where ISC fails miserably is when the device requires the original secret sauce to do well. Those Sanken MT200’s being the most obvious example and most often cited. They blow up in the applications, pure and simple. Other less demanding types do well. Drivers such and those Toshibas aren’t that hard to make these days either, and second sources for those types, which are rapidly disappearing from original sources due to lower demand, are coming out of the woodwork. Are they as good as original? Sometimes, sometimes not. Most recent I saw was for a new C4793, whose data sheet to me looked more like an MJE(F)15032. One could slap it in most places the original was used, and have it “work” reliably. Only the proper lab equipment would be able to tell you if the amp still met spec. Some people swear by the devices made by UTC and KEC. So far I haven’t seen anything “awful” out of them, but it’s not like I’ve used them by the hundreds or thousands yet so the jury is definitely out.
No, they are not ISC for sure. ISC (or these guys whoever they are) might make a passable MJ15022 - they are not that hard to make these days. Where ISC fails miserably is when the device requires the original secret sauce to do well. Those Sanken MT200’s being the most obvious example and most often cited. They blow up in the applications, pure and simple. Other less demanding types do well. Drivers such and those Toshibas aren’t that hard to make these days either, and second sources for those types, which are rapidly disappearing from original sources due to lower demand, are coming out of the woodwork. Are they as good as original? Sometimes, sometimes not. Most recent I saw was for a new C4793, whose data sheet to me looked more like an MJE(F)15032. One could slap it in most places the original was used, and have it “work” reliably. Only the proper lab equipment would be able to tell you if the amp still met spec. Some people swear by the devices made by UTC and KEC. So far I haven’t seen anything “awful” out of them, but it’s not like I’ve used them by the hundreds or thousands yet so the jury is definitely out.
Curiosity would get the better of me, and I’d saw one open and have a look-see and put one or two through their paces electrically.
It’s just a CCS with a lot of degeneration, and a main supply you can’t kill with a short duration short circuit. Heat sink needs to be big enough that it doesn’t heat way up. If I want to leave it for a while I set the fins in an ice bath. Change the emitter resistor out for different current levels. I have a nice 6 ohm dog bone that works for MJ15024’s and a set of 4 4.3 ohm sand cast that give me 3A for a lot of other general testing (3A 50 V is common). Turn up the variac to get desired collector voltage, which is some 13-14V lower than the reading. Or tie it directly to emitter if you want to be precise. You don’t need to be.
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That's all well and good ... But often the "like" part with the incorrect part number may well have totally different beta vs collector current characteristics, and the high frequency performance isn't the same (or even close). In addition, there is how consistent they are. That's important. Then there is how quickly they can degrade due to ion migration and the like, or impurities.
The "lump" type transistors made in the 1970's were easy to manufacture. They still weren't very consistent. Today's multi-emitter and whatever else you want to call them, along with much improved manufacturing means it is expensive to make a copy. That's if you pulled an original apart and got the artwork and metallurgy (chemistry or whatever you want to call it) correct. It is expensive to recreate the same thing. It would be less expensive for them to license the current part and make them properly. Now, what are the chances they are a licensed second source?
Today's new manufacture semiconductors from reputable firms are so much better than even an MJ1502x type (and I like these), it just doesn't pay to use junk. In servicing, you can't just drop a different part in for drivers or outputs either. Often you have to re-compensate the amplifier. You may end up with a radio station, or something that is a part time radio station if you don't. Even STK packs suffer from this (from Sanyo) at times. I did get replacement parts from a place that bought real parts from Japan directly and have run into this.
The "lump" type transistors made in the 1970's were easy to manufacture. They still weren't very consistent. Today's multi-emitter and whatever else you want to call them, along with much improved manufacturing means it is expensive to make a copy. That's if you pulled an original apart and got the artwork and metallurgy (chemistry or whatever you want to call it) correct. It is expensive to recreate the same thing. It would be less expensive for them to license the current part and make them properly. Now, what are the chances they are a licensed second source?
Today's new manufacture semiconductors from reputable firms are so much better than even an MJ1502x type (and I like these), it just doesn't pay to use junk. In servicing, you can't just drop a different part in for drivers or outputs either. Often you have to re-compensate the amplifier. You may end up with a radio station, or something that is a part time radio station if you don't. Even STK packs suffer from this (from Sanyo) at times. I did get replacement parts from a place that bought real parts from Japan directly and have run into this.
From my little experience as a simple enthusiast and self-builder for more than 30 years... I have come to the conclusion that, to find out if a component is 100% original, it is sometimes very difficult.
Especially when the fake is well imitated!
Carrying out a test on a component requires both a profound technical knowledge of the original component and the possibility of owning a laboratory with very expensive equipment to repeat all the tests indicated in the datasheet by the manufacturer.
I have been solving the fake problem for years by purchasing exclusively from official vendors.
For obsolete components, I prefer to replace them with other more modern equivalents that are as similar to the original as possible.
Especially when the fake is well imitated!
Carrying out a test on a component requires both a profound technical knowledge of the original component and the possibility of owning a laboratory with very expensive equipment to repeat all the tests indicated in the datasheet by the manufacturer.
I have been solving the fake problem for years by purchasing exclusively from official vendors.
For obsolete components, I prefer to replace them with other more modern equivalents that are as similar to the original as possible.
Fully agree. 100%
Not only that, but reading datasheets from these other vendors, they have no way to enforce quality control. They have no measured parameters that aren't loosely copied from a brief, nothing like real datasheets from Toshiba, or even ancient Motorola.
Why would you buy anything from a company that hasn't got a clue as to what they are making??? Warranty? How? They have no standards. By design.
Not only that, but reading datasheets from these other vendors, they have no way to enforce quality control. They have no measured parameters that aren't loosely copied from a brief, nothing like real datasheets from Toshiba, or even ancient Motorola.
Why would you buy anything from a company that hasn't got a clue as to what they are making??? Warranty? How? They have no standards. By design.
Use a modern sub. Otherwise, "one alternative" and "nothing" may well be the same thing exactly.
My point is, you have zero clue what the old number really is. It may take out other good parts. Doesn't sound like a great decision to me. Or, pay the high amount for a real old number, or a "pull". At least you know what they are.
Don't encourage purveyors of junk and lies.
My point is, you have zero clue what the old number really is. It may take out other good parts. Doesn't sound like a great decision to me. Or, pay the high amount for a real old number, or a "pull". At least you know what they are.
Don't encourage purveyors of junk and lies.
I dunno, I think it’s one place we fundamentally differ. I think it’s worthwhile to learn to separate the wheat from the chaff (things that are useable from those that are not) even if not 100% up to original spec. You just have to realize what you might be getting. It’s clear to me just from general discussion that not everyone has the means that you and I do. I still remember my lean years vividly, and simply doing nothing or limiting my horizons to 2 transistor 2N3904 preamps and 555 timers wasn’t an option either.
If you want to get technical or nit picky the Fairchild/ON BD139 everyone is so fond of isn’t up to the original Philips spec either. But it’s quite useable. I’m sure CDIL’s will work too. And no way on God’s green earth is it any 190 MHz.
If you want to get technical or nit picky the Fairchild/ON BD139 everyone is so fond of isn’t up to the original Philips spec either. But it’s quite useable. I’m sure CDIL’s will work too. And no way on God’s green earth is it any 190 MHz.
Hi wg_ski,
No, we are close to agreeing.
Most folks do not care to know, they won't test even if they have the means.
I grew up with no money. I pulled parts from TVs and traded between people I knew to get what I needed. I had to test those to make sure they were good. That was before fakes existed, but parts were pretty poor back then. A 5% resistor was precision. I even used wire for TVs and other devices.
I have to make the points I did only to show the truth. If a person elects to use unknown parts, that's on them entirely. However, some are repairing for others, or building projects for others. When you make the decision to use a mystery part, you should know what the factors are. That's all.
My message is simple and clear. A newly manufactured part marked with an old number made by a different manufacturer without license is a fake. Pure and simple. The lack of complete data is a giveaway too. Any expectation it will perform the same is wishful thinking. As long as people understand this, they can choose whatever they want.
So yeah. I made choices when I had no money. Back then a signal transistor was $10 each, but available.
No, we are close to agreeing.
Most folks do not care to know, they won't test even if they have the means.
I grew up with no money. I pulled parts from TVs and traded between people I knew to get what I needed. I had to test those to make sure they were good. That was before fakes existed, but parts were pretty poor back then. A 5% resistor was precision. I even used wire for TVs and other devices.
I have to make the points I did only to show the truth. If a person elects to use unknown parts, that's on them entirely. However, some are repairing for others, or building projects for others. When you make the decision to use a mystery part, you should know what the factors are. That's all.
My message is simple and clear. A newly manufactured part marked with an old number made by a different manufacturer without license is a fake. Pure and simple. The lack of complete data is a giveaway too. Any expectation it will perform the same is wishful thinking. As long as people understand this, they can choose whatever they want.
So yeah. I made choices when I had no money. Back then a signal transistor was $10 each, but available.
That is the reason why I buy locally from shops, or ask them to procure, as a regular purchaser their suppliers are less likely to cheat.
Case in point: one of them said BEL 2N3055 in the market were fake, offered CDIL and ST, 40 and 45 Rupees respectively.
Also offered were 2N3153 (Chinese, good enough) for 45, and original Japan for 60.
At least I am better off in the sense that the seller tells me if it is good for repair use, or junk, which is not possible in other locations.
I have used Chinese substitutes for AN1238 and TDA series 5 leg chip amps, they are reliable for that application, again got them locally.
Both the NEC and ST types are obsolete.
Case in point: one of them said BEL 2N3055 in the market were fake, offered CDIL and ST, 40 and 45 Rupees respectively.
Also offered were 2N3153 (Chinese, good enough) for 45, and original Japan for 60.
At least I am better off in the sense that the seller tells me if it is good for repair use, or junk, which is not possible in other locations.
I have used Chinese substitutes for AN1238 and TDA series 5 leg chip amps, they are reliable for that application, again got them locally.
Both the NEC and ST types are obsolete.
Well ST isn’t making TO-3 cased 3055’s anymore. Still putting it in the plastic packages as the MJE and TIP. There may be stock left in the world, but it will eventually run out. I’ve already run into my fair share of fake ST metal 2N3055’s. The “lasermarking” comes off by rubbing with your finger, and the top hats pop off with ease.
So what is the prospect of getting OnSemi 2N3055’s there? Just prohibitively expensive, or downright impossible? Some governments can get really touchy about importing…..
So what is the prospect of getting OnSemi 2N3055’s there? Just prohibitively expensive, or downright impossible? Some governments can get really touchy about importing…..
I have to ask ... why would you want a 2N3055 to begin with?
Parts go extinct for a reason. True, we can't get germanium transistors easily, but the silicon animals are replaceable with new parts. The old numbers were never laser marked to the best of my knowledge either. Nice, neat lettering on old parts screams FAKE!!!
Did Motorola discontinue 2N3055 before they became OnSemi? I'm not sure since I don't use those parts. The only thing they were good for were linear regulators, and that was the original intent of that part.
Parts go extinct for a reason. True, we can't get germanium transistors easily, but the silicon animals are replaceable with new parts. The old numbers were never laser marked to the best of my knowledge either. Nice, neat lettering on old parts screams FAKE!!!
Did Motorola discontinue 2N3055 before they became OnSemi? I'm not sure since I don't use those parts. The only thing they were good for were linear regulators, and that was the original intent of that part.