2SC3281 2SA1302 Schematic

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Does any one have a simple schematic for these transisters i have about 20 of each from some old inkel amps. im looking for a small amp desight to mabey use these devices im sick of them sitting on the boards and taking up room in my room ill sell the amps to any one that wants the parts it has a 1kv power transformer in them 1 per amp so i have 2 if you need specs please let me know. i also have 4 of 2SA1494 - 2SC3858 matched pairs

the 2sc3281 and 2sa1302 work with each other..any one... : O ) Jason
 
2SA1302 2SC3281 usage

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.
 
2SA1302 2SC3281 usage

The SA one sold as Toshiba equivalent (I paid €6 at my local dealer's), same package only black instead of green, was manufactured by Wingshing as the stamp says. They do not publish their component's data as far as I know. After blowing it up instantly I cracked both cases and saw a dye size four times smaller than the original. 15 amps? I don't think so. Some people talk about new producing techniques but I think original chip = original chip so => fake transistor. Any more experiences?
 
The Randy Slone "11.4" (from his amp construction manual book) uses these parts, and sounds extremely good. It's fairly simple in design too, but that depends on what your definition of a "simple" circuit is.

I use this amp design for most of my listening, although I'm using different BJTs on the output. From what I've read, the 3281/1302 are difficult to buy without running into fakes, so I went with newer On Semi parts instead.

If these are genuine parts, you'll have no trouble selling 'em.
 
gmarsh said:
I use this amp design for most of my listening, although I'm using different BJTs on the output. From what I've read, the 3281/1302 are difficult to buy without running into fakes, so I went with newer On Semi parts instead.
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.
 
Using OnSemi MJ21193/94s in my Leach amp and appears
to work just fine.

OnSemi has the same silicon in plastic packages; not as
much dissipation or SOA but there are a number of choices.

I would expect most any amplifier designed for bipolar
transistors would work with the transistors we've discussed
so far. Just watch out for bogus parts! Less likely to
have that problem with the more recent devices on the
market.

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 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).
 
Damon Hill said:
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.
 
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
 
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)!:bawling:

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!;)
 
tcpip said:

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?
 
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
 
Re: 2SA1302 2SC3281 usage

Mrweenie said:
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



:devilr:
 
I picked up a SAE A205 - a near unheard of SAE power amp that is built rather well and you can actually get to stuff without taking off 300 screws.
It has 4 SA1302 and 4 SC3281 per channel.
Mine came to me with no sound in both channels, no idea if someone replaced the transistors. The transistors are green and black. Maybe they were replaced and the new ones didn't work.
Anyway just wanted to post and see if someone had any ideas.
Thanks.
Srinath.
 
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