Hi doctormord,
The thread was originally intended to help people with transistors along with the poster maybe doing some measurements. Dual rectifiers might be known by some members, but they aren't the focus.
Yanking parts from built assemblies would most often come up as legit parts depending on the part type and the manufacturer. Parts most often checked here would be new parts from a store or Ebay source. Check first for known offenders by searching the thread for the vendor name and also search by part number.
The first steps you should take is to look at the data sheet from the manufacturer of that part. Then check the way the markings are applied, plus the date codes (most often wrong format for fakes). The next steps would be to check the beta (gain) and capacitance between the device junctions. You can check capacitance for diodes as well. Check other things like dimensions and lead lengths (can't on pulls). Once you have these basic things figured out, try again. That will give us something to work with.
-Chris
The thread was originally intended to help people with transistors along with the poster maybe doing some measurements. Dual rectifiers might be known by some members, but they aren't the focus.
Yanking parts from built assemblies would most often come up as legit parts depending on the part type and the manufacturer. Parts most often checked here would be new parts from a store or Ebay source. Check first for known offenders by searching the thread for the vendor name and also search by part number.
The first steps you should take is to look at the data sheet from the manufacturer of that part. Then check the way the markings are applied, plus the date codes (most often wrong format for fakes). The next steps would be to check the beta (gain) and capacitance between the device junctions. You can check capacitance for diodes as well. Check other things like dimensions and lead lengths (can't on pulls). Once you have these basic things figured out, try again. That will give us something to work with.
-Chris
just little bit of 2N3055
I bought these in four different stores , The 2 Toshiba are looking like false, the last right ST looks like fake too, you can see the ink...
The only one that can be real is the ST beside the toshiba and the fake ink ST
Any opinion ?
I bought these in four different stores , The 2 Toshiba are looking like false, the last right ST looks like fake too, you can see the ink...
The only one that can be real is the ST beside the toshiba and the fake ink ST
Any opinion ?
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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In the same order
I didn't open the other two, because I'll measure beta, but the last 2N3055 at right is a fake, look the small die..
The other toshiba opened is better, even if it is counterfeit, it's a little bit better, the die is larger..
Both had white silicone on top of die..
I didn't open the other two, because I'll measure beta, but the last 2N3055 at right is a fake, look the small die..
The other toshiba opened is better, even if it is counterfeit, it's a little bit better, the die is larger..
Both had white silicone on top of die..
An externally hosted image should be here but it was not working when we last tested it.
Your guess that those two looked like fakes seems well founded.
The dies seem especially small.
The underside view of all four looked identical. maybe indicating they were made in the same factory.
But the side view showed the caps to be rather different. So final assembly was at least using different caps.
I am always surprised to see that the inside is substantially empty.
Do any get filled with inert gas, or some heat conducting compound, or ?
The dies seem especially small.
The underside view of all four looked identical. maybe indicating they were made in the same factory.
But the side view showed the caps to be rather different. So final assembly was at least using different caps.
I am always surprised to see that the inside is substantially empty.
Do any get filled with inert gas, or some heat conducting compound, or ?
Hi,
The Toshiba devices are fine. They look right from a marking point of view (although older), and Toshiba did make them. The 2N3055 was made by multiple manufacturers. JEDEC numbers are not manufacturer specific, whereas JIS devices specify both the transistor type and characteristics and also the manufacturer. So a 2SB600
would only be made by one semiconductor company (Toshiba in this case).
It looks like you had fun taking them apart! A non-destructive test could have been done by measuring the capacitance between any two elements and comparing that to a known good sample. This wouldn't be exact, but it would tell you something about the active die size. Older JEDEC transistor manuals used to show photographs of the actual die pattern - so you could compare them as long as you had the technical information for that point in time (they can improve the process at any point).
-Chris
The Toshiba devices are fine. They look right from a marking point of view (although older), and Toshiba did make them. The 2N3055 was made by multiple manufacturers. JEDEC numbers are not manufacturer specific, whereas JIS devices specify both the transistor type and characteristics and also the manufacturer. So a 2SB600
would only be made by one semiconductor company (Toshiba in this case).
It looks like you had fun taking them apart! A non-destructive test could have been done by measuring the capacitance between any two elements and comparing that to a known good sample. This wouldn't be exact, but it would tell you something about the active die size. Older JEDEC transistor manuals used to show photographs of the actual die pattern - so you could compare them as long as you had the technical information for that point in time (they can improve the process at any point).
-Chris
Well, that's the result of my tests
For the Toshiba that I don't opened yesterday (the first at left at the picture):
For the ST:
So I conclued that the ST 2N3055 was original.. but I decided see the die.. and for my surprise..
The ST have lower beta and a thicker tab.. I belived for some minutes that he was original, but look at he die, it's very small.
For the Toshiba that I don't opened yesterday (the first at left at the picture):
Code:
Vce = 4V
Ic Beta
1,00 149
1,80 121
2,04 112
2,55 97,7
3,05 80,5
3,64 59,1
4,00 46,8
4,30 39,6
4,70 27,9
Tab thickness: 1,43 mmFor the ST:
Code:
Vce = 4V
Ic Beta
1,00 282
1,64 101
1,81 62,1
2,00 47,4
2,10 37,1
2,30 27,6
3,00 9,1
Tab thickness: 1,51 mmSo I conclued that the ST 2N3055 was original.. but I decided see the die.. and for my surprise..
An externally hosted image should be here but it was not working when we last tested it.
The ST have lower beta and a thicker tab.. I belived for some minutes that he was original, but look at he die, it's very small.
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That and the Toshiba has a heat spreader (the extra metal under the die). The difference in die size could be that the Toshiba is a tougher part while the ST may meet the specs for a 2N3055.
The 2N3055 isn't a great transistor for audio use. It was designed for power supplies and sold in high numbers for that purpose. Later on someone decided to use it for cheap audio outputs, but the original ones were only good for 60 Vce and were slow devices. Perfect for the 24 volt industrial power supplies, maybe even 48 VDC supplies. So today we have the 2955 and the same die in different packages.
If you want good audio output devices, consider the MJ15022 / 23 or MJ15003 / 04. At least they were designed for the job and give excellent performance. Buy them from the normal distributor - dealer sales network and you will make ever $ count - 'cause they are all real.
If you want to experiment with various suppliers, but the real deal to start. Then you have something to compare those devices to. Between measuring capacitance and beta (DC gain), you should have a high confidence you have the right parts. Of course, having the correct case style and lettering should be your first checks. Datasheets tend to lay out the exact format of any printing on the case. Check it.
-Chris
The 2N3055 isn't a great transistor for audio use. It was designed for power supplies and sold in high numbers for that purpose. Later on someone decided to use it for cheap audio outputs, but the original ones were only good for 60 Vce and were slow devices. Perfect for the 24 volt industrial power supplies, maybe even 48 VDC supplies. So today we have the 2955 and the same die in different packages.
If you want good audio output devices, consider the MJ15022 / 23 or MJ15003 / 04. At least they were designed for the job and give excellent performance. Buy them from the normal distributor - dealer sales network and you will make ever $ count - 'cause they are all real.
If you want to experiment with various suppliers, but the real deal to start. Then you have something to compare those devices to. Between measuring capacitance and beta (DC gain), you should have a high confidence you have the right parts. Of course, having the correct case style and lettering should be your first checks. Datasheets tend to lay out the exact format of any printing on the case. Check it.
-Chris
That looks like a file photo of the real thing.
You know how much these are worth, and they are not inexpensive at all. How much are you trying to buy them for, or how much did that one cost you?
Step number 1. Examine the data sheet to see if the markings look right.
Sanity check, try another op amp in that socket. Even a 1458 or 4558 should tell you if the circuit is in fact working properly.
-Chris
You know how much these are worth, and they are not inexpensive at all. How much are you trying to buy them for, or how much did that one cost you?
Step number 1. Examine the data sheet to see if the markings look right.
Sanity check, try another op amp in that socket. Even a 1458 or 4558 should tell you if the circuit is in fact working properly.
-Chris
I have to say that picture has from ebay, not the ones I have. My chip has not a dot on pin 1 like this one have.
I have no 4458 or tl072 chip, otherwise I had already now if it did work, have order some others.
regards
Hi,
Well these chips will normally run in the $10 US range depending on authorized supplier. Not a chip you would use everywhere. I have used them, and they perform extremely well. If you don't have normal dual and single op amps on hand, perhaps you should pick a few up just to have them if needed? The basics would be things like the TL071 / TL072 (J-Fet input types), 4558 (standard bipolar input) and maybe some NE5532 and NE5534 chips (higher performance and very good for audio). Buy a few from authorized dealers first. This will allow you to compare your Ebay finds with the real deal. You could then test different parameters and compare that to your unknown chips.
Can you post a photo of the chip you actually received?
-Chris
Well these chips will normally run in the $10 US range depending on authorized supplier. Not a chip you would use everywhere. I have used them, and they perform extremely well. If you don't have normal dual and single op amps on hand, perhaps you should pick a few up just to have them if needed? The basics would be things like the TL071 / TL072 (J-Fet input types), 4558 (standard bipolar input) and maybe some NE5532 and NE5534 chips (higher performance and very good for audio). Buy a few from authorized dealers first. This will allow you to compare your Ebay finds with the real deal. You could then test different parameters and compare that to your unknown chips.
Can you post a photo of the chip you actually received?
-Chris
I did found the error, I had the pol caps on input in wrong polarity, so thing go wrong, now it do work with the chips I have ordered.
As mother always say, the simple things are the most difficult.
regards