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Old 27th July 2012, 03:30 PM   #231
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Nice radio David!

I am afraid I have some bad news, but when I see the 2SA968's on your board I think they are not original Toshiba. Especially the right one seems to be fake because the Toshiba logo is printed on it. Original ones look different. Original ones with the T Toshiba logo should look like these: http://michaelq.home.xs4all.nl/Proje...a2sc%20(2).JPG
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Old 27th July 2012, 05:18 PM   #232
neychi is offline neychi  Croatia
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Yes David, I'm afraid Michael has right. The left one could be original KEC, but the right one is probably a fake. It will be a shame to spoil such a beautiful amp with a nasty components. It could work, but how...that is the question.
Btw Michael, genuine 2sa968/2sc2238 came with two Toshiba logos, old T and...
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Old 27th July 2012, 10:47 PM   #233
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Hmm, I hope David did not buy the MJ15003/4's from Ebay also. Buying trannies from Ebay is very risky. Best is to buy from official partners. Like Digikey which is a official partner from ONsemi.

Ahaa, I did not know that the 2SC968 / 2SC2238 came with the new logo too. I only knew the green and black version with the T-logo.

I've decoupled the KSA by the way. It is now time to wire GND in the cabinet. Will receive some nylon sleeves soon (company shipped wrong nylon sleeves, so had to wait for that). I promised to publish some pictures of the orientation of the boards. Now everything is disconnected I could make a photo easier. Here it is:

Click the image to open in full size.

I am proud of the results I've used some spacers to connect the cables to. Very strong and relieable connection that almost can't corrode.

And I have some other news, I finally have a Fluke multimeter!!! Although my other multimeter (Velleman DVM890) is very good and reliable (bought it back in 2006, never experienced any problems with it) I wanted to have a Fluke. But they are so expensive....... till today. Bought one for a very reasonable price second handed. It is a Fluke 175.

Little picture:
Click the image to open in full size.

It is in great condition. The original little plactic protection shield was even mounted to the display. It is unbelievable what kind of quality this meter has. What I really like about it is the ability to check capacitors. It has also all kinds of safety things build in, like when you measure resistance and there is lot of voltage across the resistor it it bleeps, when you want to measure at a capacitor which is still charged it bleeps and so on. So you always know you are doing something wrong (did not try these things btw, but the manual says it ).

Well I am going to watch the opening of the Olympic Games further , good night all

Last edited by Kaplaars; 27th July 2012 at 10:50 PM.
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Old 28th July 2012, 01:50 AM   #234
spurlte is offline spurlte  United States
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Quote:
Originally Posted by neychi View Post
Yes David, I'm afraid Michael has right. The left one could be original KEC, but the right one is probably a fake. It will be a shame to spoil such a beautiful amp with a nasty components. It could work, but how...that is the question.
Btw Michael, genuine 2sa968/2sc2238 came with two Toshiba logos, old T and...
I just remembered that I got these from Mouser Electronics, USA. So they should be legit. It was the 2SK2013/2SJ313 I purchased through ebay from Israel. Here is their store site on ebay:

4x 2SJ313 + 2SK2013 Original Toshiba MOSFET (2 + 2) | eBay
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Old 28th July 2012, 12:24 PM   #235
neychi is offline neychi  Croatia
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David, don't mess up with transistors of suspicious origin if you can't get the real mccoy. Get 2sa1011/2sc2344 like I told you. Mouser is no guarantee that these are the original transistors. A few years ago I ordered via RS Components Toshiba's 2sa968/2sc2238 and got Magnatec. They work fine but these were actually 2sa1011/2sc2344 transistors with polished front and re-printed logo and product labels. I've made a comparison. I even went well, but their price was pretty high and I could get a two original transistors for price of one. Just be careful.
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Last edited by neychi; 28th July 2012 at 12:31 PM.
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Old 28th July 2012, 12:30 PM   #236
spurlte is offline spurlte  United States
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What a 2012 Olympian opening show! I have here a post from AudioKarma
Toshiba 2SC2238 + 2SA968 counterfeits? [Archive] - AudioKarma.org Home Audio Stereo Discussion Forums
It talks about 2SA1837/2SC4793 as substitutes. I see that the only difference is that the Ic=1A. The 2sa968's Ic=1.5. Is this a big difference for the KSA 100?
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Old 28th July 2012, 12:34 PM   #237
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I could not agree with Dean more I have very bad experiences with cloned / fake transistors. Repaired a Denon PMA-920 once. Replaced the original Sanken outputs for ISC's. 5 seconds full power at the dummy and BOOM. Sliced the trannies open, and.... well see for yourself, compaire the dies (left ISC, right good ol' Sanken):

Click the image to open in full size.

That little joke made the repair even more costly, could replace the drivers again, and now the biastransistor and emitterresistors were broken also.
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Old 28th July 2012, 12:35 PM   #238
neychi is offline neychi  Croatia
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2SA1837/2SC4793 are not direct substitution, 2sa1011/2sc2344 are.

Semiconductor Substitution List



Edit: Michael, congratulation! Excellent Fluke
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Last edited by neychi; 28th July 2012 at 12:39 PM.
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Old 28th July 2012, 12:40 PM   #239
spurlte is offline spurlte  United States
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Quote:
Originally Posted by neychi View Post
David, don't mess up with transistors of suspicious origin if you can't get the real mccoy. Get 2sa1011/2sc2344 like I told you. Mouser is no guarantee that these are the original transistors. A few years ago I ordered via RS Components Toshiba's 2sa968/2sc2238 and got Magnatec. They work fine but these were actually 2sa1011/2sc2344 transistors with polished front and re-printed logo and product labels. I've made a comparison. I even went well, but their price was pretty high and I could get a two original transistors for price of one. Just be careful.
Thanks.
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Old 28th July 2012, 01:11 PM   #240
spurlte is offline spurlte  United States
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neychi, I talked to the owner of this electronic components store in New Jersey, USA
2SA1011 pdf 2SA1011 datasheet PNP Epitaxial Planar Silicon Transistor - High-voltag Switching - AF Power Amp - 100W Output Predriver Application 2.51735 Transistors Bipolar Silicon PNP Power Transistors American Microsemiconductor 2SA1011 available a as I found the 2SA1011 but not the the 2SC2344. I called and got the top man himself. He took all my information regarding the 2SA968/2SC2238 and the 2sa1011/2sc2344 and said he will get back to me shortly, at least by Monday. You guys are my guardian angels and I owe you a cold beer. And I also see the specs for the 2sa1011 where the Ic-1.5A. Nice
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