2SC3281 2SA1302 Schematic - Page 2 - diyAudio
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Old 9th April 2004, 01:33 PM   #11
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I have blown many pairs of the 2sc3281/2sa1302's recently. I purchased them from Parts Express which I assumed to be a reputable distributor. I have never had any parts fail as easily as these. Even with the slightest of circuit instabilities, wham... they're gone everytime. They're very sensitive to high frequency as well. But, when they run they sound great. ??

it's definitely time to move onto the other newer types (2sc5200/2sa1943).
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Old 9th April 2004, 07:26 PM   #12
tcpip is offline tcpip  India
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Quote:
Originally posted by Damon Hill
Recommend getting both Doug Self's and Randy Sloan's
books on audio power amplifier design to get an overview
of design possibilities.
I have three of Randy Slone's books, including the "High Power Audio Amp Construction Manual." Can't claim that I understand everything in them, but at least I know what he's talking about. It was from this book that I came to know of the "Figure 11.4" BJT amp.
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Old 9th April 2004, 07:41 PM   #13
Rimband is offline Rimband  United States
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Hi guys, you may want to check out this link;

counterfiet sa1943's ??
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Old 9th April 2004, 08:20 PM   #14
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Thanks for the link Rimband, we can't even trust the new ones.

I'll probably purchase some from digi-key in the next couple weeks, and bench test the first set I get(2sc5200/2sa1943). If there's a sure problem then i'll give them a call, but I think they'll be ok.
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Old 9th April 2004, 09:19 PM   #15
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Quote:
I have blown many pairs of the 2sc3281/2sa1302's recently. I purchased them from Parts Express which I assumed to be a reputable distributor. I have never had any parts fail as easily as these. Even with the slightest of circuit instabilities, wham... they're gone everytime. They're very sensitive to high frequency as well. But, when they run they sound great. ??
This doesn't sound at all good; as you say, time to move to
newer parts. On my next order to Parts Express, I might order
some of those transistors and test them, including cracking a
couple open to see what's on the inside. That makes me want
to stick strictly to OnSemi parts.

--Damon
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Old 11th April 2004, 04:01 AM   #16
Rimband is offline Rimband  United States
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No problem, cblakeslee, I just don't want you and others to go through the nightmare I went through. My best bet would be to forget the Japanese semiconductors and go for On Semi. Nothing against our Japanese friends, but it seems in this realm, they get faked more then On.

The Carver amp I rebuilt is the same as the one I bought in 1994, that one uses (back then) MJL3281A and MJL1302A transistors, and that amp is about indestructable. I use both amps, plus a smaller (TFM-6CB) amp in a tri-amp setup with an MTM speaker system(s), the amp I rebuilt drives my subwoofers. The amp with the MJL's drive my MTMs' midwoofers, and the small amp drives my Morel Tweeters. Tonight, I pushed the subwoofer amp into clipping (I'd rather hear an amp clip than have it blow up)!

Guys, this is no problem informing you about the fake semiconductors, but my credit should go to Rod Elliott. Please give him credit for pointing this out, I will try to spread the word the best I can about fake transistors and the problems they have caused!

Take care, and good luck with your amplifiers!

http://sound.westhost.com

P.S.>Not trying to advertise, but I need to pay back a favor to Rod, since he first posted this, I owe him one!
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Old 12th April 2004, 03:18 PM   #17
gmarsh is offline gmarsh  Canada
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Quote:
Originally posted by tcpip

Just curious.... which OPS devices are you using? Did you face any stability problems with them? I'm particularly keen to know whether anyone's used the 1943/5200 pair with this amp. This pair of devices is in production and can be safely purchased from Digikey etc, so it would be very good if one could use it with this amp. From all accounts, this is one hell of an amp.

Of course, there's always the alternative of using 15003/4 pair from OnSemi... Randy himself recommends them as an alternative in his book.
I'm using the MJL3281A / MJL1302A pair. I'm also using MJE344/MJE350 instead of the 2SB/2SD transistors.

I've heard of people running into stability issues with this amp, but I haven't had any problems myself. I used a 2-layer board (ExpressPCB 3.8x2.5" special) packed very tightly, so it could be layout issues that people are having. Who knows?
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Old 12th April 2004, 04:02 PM   #18
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I've used the On Semi versions, the MJL3281 and MJL1302 without problems, but Digikey is a very reliable distributor and they do have "genuine" Toshiba parts; though not a big selection, they have the main ones. MCM is good for older parts, including differential bipolar and JFET sets, but I've never bought the big power devices from them. Their re-packaging and handling, and general speed of service isn't quite up to the same standards as Digikey, which is a true world class disti in the US and Canada. Also, Digikey's prices are pretty low.

While you're browsing Digiky (download the current catalog PDF), don't over look their stock of Nichicon HE caps; very competitive prices on these low ESR types.

Regards,

Jon
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Old 16th June 2004, 07:47 PM   #19
K-amps is offline K-amps  United States
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Default Re: 2SA1302 2SC3281 usage

Quote:
Originally posted by Mrweenie
One amp that uses the 1302 and 3281 is luxman M02, looking for the drawings myself actually. Want to sell me a few pairs? I have been too greedy to feed the amp a 1kHz block wave to test its performance then an output pair was blown... then my replacement turned to be a bad one from Wingshing.
I sold My M-02, thats a sweet amp. (Good looker too). If I remember it has 2 pairs of the 1302/3281 and puts out 140w/ch.

Once came to me blown, I fixed it with the 1943/5200.

I now have a couple of Lux M-117's, another sweet amp. I plan to bridge them for my JBL 2226's



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