I've just received some Toshiba SA1943's from my regular supplier.
Previously these have been in a geen package with "Toshiba 2SA1943" and other text written on them.
This recent batch are all in black packages, some with the usual text but some just have "A1943" written on them.
Has anyone else received these devices like this?
Could these be counterfeit/clone devices or have toshiba changed their packaging and labeling?
I also had 2SC5200's in this order but they were the same as usual.
Previously these have been in a geen package with "Toshiba 2SA1943" and other text written on them.
This recent batch are all in black packages, some with the usual text but some just have "A1943" written on them.
Has anyone else received these devices like this?
Could these be counterfeit/clone devices or have toshiba changed their packaging and labeling?
I also had 2SC5200's in this order but they were the same as usual.
If they are not marked Toshiba they could be clones that are perfectly fine, or they could be sub-standard devices. However, if not marked Toshiba, I don't think you would have any real argument that they were fake as the supplier could say, "well, company X 2SA1943 is supposed to only be 34W dissipation" or somesuch other rubbish comment. If they are advertising them as Toshiba, that's a different story.
I bought some counterfeit of 2sa1943/2sc5200. all marked
with toshiba logo and the outlook is nice too......however,
when I power up the amplifier and apply some test signal to it,
WoW......they brun !!! All die at once! So horrible!
after I replace those counterfeit with orginal, everything fine!
I may post the photos of them later 🙂
with toshiba logo and the outlook is nice too......however,
when I power up the amplifier and apply some test signal to it,
WoW......they brun !!! All die at once! So horrible!
after I replace those counterfeit with orginal, everything fine!
I may post the photos of them later 🙂
A simple way to distinguish fake devices from the originals is measuring zero-bias BE and BC capacitances
Original devices usually have higher capacitances due to higher die sizes. Each model tends to have typical capacitance values with little deviation from lot to lot
In the other hand, fake devices have lower capacitances due to smaller die sizes and each lot of fakes has different capacitance from the others due to different dies being used
Capacitance tends to be a good indicator of die size for bipolar transistors
Almost all fakes end blowing due excessive dissipation because of too small die size or too low Vce rating. Some may also oscillate when placed in an amplifier due to too low FT and excessively long switching times
Original devices usually have higher capacitances due to higher die sizes. Each model tends to have typical capacitance values with little deviation from lot to lot
In the other hand, fake devices have lower capacitances due to smaller die sizes and each lot of fakes has different capacitance from the others due to different dies being used
Capacitance tends to be a good indicator of die size for bipolar transistors
Almost all fakes end blowing due excessive dissipation because of too small die size or too low Vce rating. Some may also oscillate when placed in an amplifier due to too low FT and excessively long switching times
I thought once I had some counterfeits because the went up in smoke when powered up. Turned out it was me putting them into 400kHz oscillation through a form of klutzyness I'm too embarrassed to mention.
Toshiba's practice has been to package the PNP's in green epoxy, so those are probably fakes. Whether they are good parts is another issue. I don't know who else makes these, I've only seen the Toshiba catalog. Maybe Samsung??
If you can, return them for a credit. No sense risking other good parts if you are not comfortable with them.
If you can, return them for a credit. No sense risking other good parts if you are not comfortable with them.
I've seen clones labelled 'KSA1943' and 'KSC5200' used in some amplifiers. They are apparently made by Samsung, both NPN and PNP come in black case and appear to be reliable
From my experience the new Toshiba 2SA1943 is now black in Color.At first I was also curious on the change of color but I subjected the new transistors to a torture test.At +- 75 volts and a 4 ohm load with only 2 pcs. per side it passed with flying colors.The KSA14943 and KSA5200 is manufactured by Fairchild it also passed the torture test.Hope this helps.
MGR
MGR
I got some 2sc 5359 (5200's elder bro) and the complement 2sa1987, both have Toshiba markings and are black.
However there are 2 kinds of 2sc5359 with slightly different fonts... I broke it up and checked the die sized were a little different.... probably fake, but is there a chance that a later batch may have slightly smaller die's?
Also the dies are slightly smaller than the 2sa1302....
Something smells right? 😡
-K.
PS Malloryn got any pictures you can post?
However there are 2 kinds of 2sc5359 with slightly different fonts... I broke it up and checked the die sized were a little different.... probably fake, but is there a chance that a later batch may have slightly smaller die's?
Also the dies are slightly smaller than the 2sa1302....
Something smells right? 😡
-K.
PS Malloryn got any pictures you can post?
Digi-Key is now offering Toshiba 1943s and 5200s, and the prices aren't too bad. If I weren't fixated on FETs, I'd try some...
This thread about counterfeits made me want to go back and look at what I have in stock. I have mucho stock for the amps I repair and occasionally design.
I found 10 pieces of Mj15222 and MJ15223 that may be fake. They are labelled in thin red ink that easily washes off with acetone. The labelling is "MEV / MJ15222 / '7E" in three lines, parallel to the long dimension of the TO-3 case. I was going to use these in an amp I am building, but now I want to open one or two up to see if the die is reasonable in size. I'll try the curve tracer too, but that does not load the parts and the fakes seem to be quasi functional, but small and unable to handle much power.
I will not be buying MEV brand again or using that source. But suddenly a problem that seemed remote is very close, and I wonder about all the parts I have now. Just what we don't need....
I found 10 pieces of Mj15222 and MJ15223 that may be fake. They are labelled in thin red ink that easily washes off with acetone. The labelling is "MEV / MJ15222 / '7E" in three lines, parallel to the long dimension of the TO-3 case. I was going to use these in an amp I am building, but now I want to open one or two up to see if the die is reasonable in size. I'll try the curve tracer too, but that does not load the parts and the fakes seem to be quasi functional, but small and unable to handle much power.
I will not be buying MEV brand again or using that source. But suddenly a problem that seemed remote is very close, and I wonder about all the parts I have now. Just what we don't need....
Since its is marked MEV and not Motorola, one would think it is not a fake but a genuine (but substandard) re-production by another company.... unless this was a fake based on an MEV original... LOL. 😀
I found 10 pieces of Mj15222 and MJ15223 that may be fake. They are labelled in thin red ink that easily washes off with acetone. The labelling is "MEV / MJ15222 / '7E" in three lines, parallel to the long dimension of the TO-3 case. I was going to use these in an amp I am building, but now I want to open one or two up to see if the die is reasonable in size. I'll try the curve tracer too, but that does not load the parts and the fakes seem to be quasi functional, but small and unable to handle much power.
I will not be buying MEV brand again or using that source. But suddenly a problem that seemed remote is very close, and I wonder about all the parts I have now. Just what we don't need.... [/B][/QUOTE]
MEV is a former hungarian company. They made some OEM works for Motorola in the 80's, and 90's. They made also Motorola labelled devices...
Sajti
I will not be buying MEV brand again or using that source. But suddenly a problem that seemed remote is very close, and I wonder about all the parts I have now. Just what we don't need.... [/B][/QUOTE]
MEV is a former hungarian company. They made some OEM works for Motorola in the 80's, and 90's. They made also Motorola labelled devices...
Sajti
Bitten by fake transistors
Hello guys, I too have been bitten by fake transistors myself, and to read about the 2SA1943/2SC5200 being faked just about brings tears to my eyes. That does not make me a happy pappy, that galls me to the core.
I bought a Carver amplifier off E-bay, the seller did say the left channel was bad. I figured, that's no problem, I can repair it. When the amp arrived, I saw that the middle pair of output transistors (2SA1302/2SC3281) were bad, plus a few resistors and a small transistor (2SC2241) and a melted speaker relay.
I figured no problem, the parts won't be expensive (I figure about $20.00 US) in parts, and the amp would be good again. However when I bought the 2SA1302/2SC3281 pair, they just didn't look right. I will try to post photos of the amp and the transistors.
I threw caution to the wind and went ahead and rebuilt the left channel of the amp, only to have it fail miserably (ever see sparks shoot out of the ventilation holes?).
I thought I'd done something wrong and went over the whole left channel again (with a fine toothed comb) and rebuilt it again. It failed again, with the same fireworks show.
Then at work, I ran across Rod Elliott's site (http://sound.westhost.com) and read his article about counterfiet transistors, and my blood just about boiled on the spot. I think the burn marks are still there on the ceiling!😡
Thank you Rod, if I ever meet you I would like to
with you and get 
.
I rebuilt the amp again with the original transistors, and it works like a raped ape, I rattle the walls just about every weekend with the amp without fail. (I blew up a Cerwin-Vega woofer one weekend, tore the spider off the frame and burnt the voicecoil to a cinder).
I will try to post the pictures in order, the amp itself first, the bogus transistors, the bogus transistor's die, and the original transistors. (I wish I could post the blown originals' dies, but I couldn't, I tossed them.)
Sajti, if you can (and others), please post pictures of your transistors better yet if you can open them up without destroying the die. Don't take fakes for granted, check them out before you put them in an amp, it can save you a lot of grief.
Sorry about the long post, but this trend in faked semiconductors bothers me, and what bothers me more is the fact that I've seen this issue dismissed on this board.
Take care guys, good luck on your transistors!🙂
Hello guys, I too have been bitten by fake transistors myself, and to read about the 2SA1943/2SC5200 being faked just about brings tears to my eyes. That does not make me a happy pappy, that galls me to the core.
I bought a Carver amplifier off E-bay, the seller did say the left channel was bad. I figured, that's no problem, I can repair it. When the amp arrived, I saw that the middle pair of output transistors (2SA1302/2SC3281) were bad, plus a few resistors and a small transistor (2SC2241) and a melted speaker relay.
I figured no problem, the parts won't be expensive (I figure about $20.00 US) in parts, and the amp would be good again. However when I bought the 2SA1302/2SC3281 pair, they just didn't look right. I will try to post photos of the amp and the transistors.
I threw caution to the wind and went ahead and rebuilt the left channel of the amp, only to have it fail miserably (ever see sparks shoot out of the ventilation holes?).
I thought I'd done something wrong and went over the whole left channel again (with a fine toothed comb) and rebuilt it again. It failed again, with the same fireworks show.
Then at work, I ran across Rod Elliott's site (http://sound.westhost.com) and read his article about counterfiet transistors, and my blood just about boiled on the spot. I think the burn marks are still there on the ceiling!😡
Thank you Rod, if I ever meet you I would like to
with you and get .I rebuilt the amp again with the original transistors, and it works like a raped ape, I rattle the walls just about every weekend with the amp without fail. (I blew up a Cerwin-Vega woofer one weekend, tore the spider off the frame and burnt the voicecoil to a cinder).
I will try to post the pictures in order, the amp itself first, the bogus transistors, the bogus transistor's die, and the original transistors. (I wish I could post the blown originals' dies, but I couldn't, I tossed them.)
Sajti, if you can (and others), please post pictures of your transistors better yet if you can open them up without destroying the die. Don't take fakes for granted, check them out before you put them in an amp, it can save you a lot of grief.
Sorry about the long post, but this trend in faked semiconductors bothers me, and what bothers me more is the fact that I've seen this issue dismissed on this board.
Take care guys, good luck on your transistors!🙂
Could you measure zero-bias C-B and C-E capacitances of all these devices?
A simple capacitor tester should be more than enough to perform these measurements as long as it uses voltages low enough and no DC
For genuine devices you should get 5-10nF capacitance values, for counterfiet devices capacitances may be as low as 1-3nF [due to much smaller die sizes]
If somebody has some transistors known to be genuine , it would be a great idea to measure its capacitances and post the values here to help other people to know if their devices are genuine
A simple capacitor tester should be more than enough to perform these measurements as long as it uses voltages low enough and no DC
For genuine devices you should get 5-10nF capacitance values, for counterfiet devices capacitances may be as low as 1-3nF [due to much smaller die sizes]
If somebody has some transistors known to be genuine , it would be a great idea to measure its capacitances and post the values here to help other people to know if their devices are genuine
OK Eva decipher this 😀
I used a Elenco CM-1555 cap checker. (uses a 9v battery/psu) I do not beieve it passes any DC but sends an AC frequency to the device under test and measures the attenuation...anyway
I got different readings based on the polarity of the leads I used.
For the good pair (ones on left in the picture)
with Black probe on C, I got:
CE=403 pF
CB=12.63 nF
With red probe on C, I got:
CE=401pF
CB=441pF
For the bad part (which I think is fake, rt one in picture)
with black probe on C I got:
CE=390pF
CB=797pF
With red probe on C I got:
CE=407pF
CB=503pF
Looks like the good ones have larger die, but I cannot still say if even they are genuine.
K- 😡
I used a Elenco CM-1555 cap checker. (uses a 9v battery/psu) I do not beieve it passes any DC but sends an AC frequency to the device under test and measures the attenuation...anyway
I got different readings based on the polarity of the leads I used.
For the good pair (ones on left in the picture)
with Black probe on C, I got:
CE=403 pF
CB=12.63 nF
With red probe on C, I got:
CE=401pF
CB=441pF
For the bad part (which I think is fake, rt one in picture)
with black probe on C I got:
CE=390pF
CB=797pF
With red probe on C I got:
CE=407pF
CB=503pF
Looks like the good ones have larger die, but I cannot still say if even they are genuine.
K- 😡
Obtaining different capacitance values depending on the polarity means that your capacitor tester is applying some DC
Try to filter out the DC using something 10uF in series with the capacitor tester a 1Megohm in paralell to the junction of the transistor
The other problem may be your capacitor tester using a too high test voltage [>500mVpp]. This is harder to circumvent but placing 1nF or 2.2nF in series with the juction to attenuate te measuring signal may work, but then you have to calculate the effective capacitance of the juction based on the measurement [for series capacitors : 1/C_measured = 1/C1 + 1/C2]
My capacitor tester [Monacor LCR-4000] works fine for transistors and diodes because it uses no DC [internally AC coupled] and the test signal is a 600mV p-p sine wave [not enough to turn on the juction diodes]
EDIT : You made a little mistake when measuring, the capacitances you have to measure are C-B and E-B, not C-E
Try to filter out the DC using something 10uF in series with the capacitor tester a 1Megohm in paralell to the junction of the transistor
The other problem may be your capacitor tester using a too high test voltage [>500mVpp]. This is harder to circumvent but placing 1nF or 2.2nF in series with the juction to attenuate te measuring signal may work, but then you have to calculate the effective capacitance of the juction based on the measurement [for series capacitors : 1/C_measured = 1/C1 + 1/C2]
My capacitor tester [Monacor LCR-4000] works fine for transistors and diodes because it uses no DC [internally AC coupled] and the test signal is a 600mV p-p sine wave [not enough to turn on the juction diodes]
EDIT : You made a little mistake when measuring, the capacitances you have to measure are C-B and E-B, not C-E
Eva said:
I got the CB/CE from your previous post.... 😀
Anyway, I measured my cap checker, lo and behold is spews out 1004mV AC and about 1.2v dc.
I am not sure I can perform the readings you want because placing a 10uF in series will make the reading high enough i.e. I will have to step toa lower sensitivity setting that will make me lose the decimals to measure the smaller values
... based on what I had previously... can any inference be made?
-K
Oops, the mistake was mine when typing, sorry
Placing a 10uF capacitor in series won't affect the measurement since it will appear as a short circuit in series with the junction, but it will filter all the DC
For example, I have here some genuine Sanken transistors that measure :
2SC3264 : C-B = 1nF, E-B = 10nF
2SA1295 : C-B = 1.7n, E-B = 8.4nF
I also got some fake 2SC3264 that measured C-B = 0.5nF and E-B = 2.7nF
I opened a fake device and a genuine device and found that capacitance figures were a very good indicator of die size
You can take it as a reference since these devices are rated at 230V, 17A, 200W, 2A@100V S.O.A. and Ft>40Mhz
Your devices may be all fake since the 12nF C-B figure is clearly due to junction diode turn-on [measuring in the other direction may work] and is not real, and the rest of measurements are almost equal
Knowing E-B capacitances would help to decide
Placing a 10uF capacitor in series won't affect the measurement since it will appear as a short circuit in series with the junction, but it will filter all the DC
For example, I have here some genuine Sanken transistors that measure :
2SC3264 : C-B = 1nF, E-B = 10nF
2SA1295 : C-B = 1.7n, E-B = 8.4nF
I also got some fake 2SC3264 that measured C-B = 0.5nF and E-B = 2.7nF
I opened a fake device and a genuine device and found that capacitance figures were a very good indicator of die size
You can take it as a reference since these devices are rated at 230V, 17A, 200W, 2A@100V S.O.A. and Ft>40Mhz
Your devices may be all fake since the 12nF C-B figure is clearly due to junction diode turn-on [measuring in the other direction may work] and is not real, and the rest of measurements are almost equal
Knowing E-B capacitances would help to decide
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