Haha, this amp is very frustrating!
The main output transistors are the 2SA1492 and 2SC3856, which are made by Sanken and are the original parts. For the drivers, I couldn't find the original parts, but I found equivalents which seem to work no problem, they are 2SA968 (replaces 2SA1659A) and 2SC2238 (replaces 2sc4370a), both made by KEC, which is the manufacturer of the original drivers. I believe Toshiba also made them, and there may be a newer equivalent from them if you can't find them either.
I don't know if there are any equivalents for the original output transistors, but it's possible. If you can't find any of these, you may have to buy the parts from another country. Not sure if they ship overseas, but the company I bought some from www.bdent.com (in the US), had fair prices and seems to sell legitimate parts.
The main output transistors are the 2SA1492 and 2SC3856, which are made by Sanken and are the original parts. For the drivers, I couldn't find the original parts, but I found equivalents which seem to work no problem, they are 2SA968 (replaces 2SA1659A) and 2SC2238 (replaces 2sc4370a), both made by KEC, which is the manufacturer of the original drivers. I believe Toshiba also made them, and there may be a newer equivalent from them if you can't find them either.
I don't know if there are any equivalents for the original output transistors, but it's possible. If you can't find any of these, you may have to buy the parts from another country. Not sure if they ship overseas, but the company I bought some from www.bdent.com (in the US), had fair prices and seems to sell legitimate parts.
rkc7 said:
Looks to me like a fairly (and unnecessarily) complicated class-AB amplifier. Have you ever tried to reduce distortion by placing an electrolyte in parallel with an MKT-cap between the drains of Q109 and Q110?
rkc7 said:
2SA1294/2SC3263, affordable and can be bought in any corner of the big peanut.
They're actually twice as good as the originals: SOAR has 2 times higher current for DC and 5 times higher for 100mS.
1 Dollar the Watt is value for money, imo.
MatchASM said:
Can't say I'm familiar enough with amplifier circuit operation to have even thought of that, haha. If I'm ever feeling adventurous, I'll give it a try.
jacco vermeulen said:
Can't really find many places that carry them using Google... only Profusionplc.com has it listed as a Sanken part, but shipping charges would be kinda high for me being in the US ($50, almost doubling the cost of replacing all outputs!) but good for those in Europe, I suppose.
After a hard fight with both channels my Samson S1000 works. I've got the best results with 2SA1516 and 2SC3907 powertransistors. But now i need to re-adjust the idle settings for each channel. RKC7, do you got these? Or is it possible that you can measure this with you're own amplifier? Thank you anyway! (And still this is a crappy amp!😀 😀 
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Tell me at what points you want measured for what, I'm not sure what "idle settings" measurements are.
You can measure this with a voltmeter. You put the multimeter pins on the emitters (outputs) from one PNP and one NPN output powertransistors. The measured unit is in mV (milliVolt). But be carefull, if you contact 2 pins of one transistor your amplifier will be fried...
Do you want it run for any amount of time?
The values seemed to drop after turning it off and on a few times.
The last reading for my first channel was 10.6mV, second channel was 9.6mV. That was across the outputs of the pair nearest to the front of the amp on both channels. Seems ch 2 was consistently lower than ch 1, does that suggest the amp needs bias set or is that an acceptable difference?
The values seemed to drop after turning it off and on a few times.
The last reading for my first channel was 10.6mV, second channel was 9.6mV. That was across the outputs of the pair nearest to the front of the amp on both channels. Seems ch 2 was consistently lower than ch 1, does that suggest the amp needs bias set or is that an acceptable difference?
That diffrence is really acceptable. But i think that you get better measure results if the amp has been warmed up for a 15 minuts or more? Anyway, i would like to thank you that youre measure it for me! Thsnk you very much!
I let it idle for about 15-20min, measured on channel one 10.2-10.3mV, ch 2, 9.3-9.4mV.
If I adjust VR101 on one of the channels, I should be able to adjust that voltage to match the other, correct? Mostly I just want it to be OK when bridged.
If I adjust VR101 on one of the channels, I should be able to adjust that voltage to match the other, correct? Mostly I just want it to be OK when bridged.
Hi,
is this amp designed to be bridged?
Why was it in need of new transistors?
The bridging rule is; double the power into double the load impedance.
If you don't double the load impedance you will end up with another dead amplifier.
is this amp designed to be bridged?
Why was it in need of new transistors?
The bridging rule is; double the power into double the load impedance.
If you don't double the load impedance you will end up with another dead amplifier.
yes, it has a bridging switch on back. It had blown some output transistors before, but I have fixed it and had it running at a moderate volume for about 30 min no problem and overnight with pink noise no problem.
I also fried my output devices on both channels. I recieved an email from my Samson dealer here in Holland, and he tells me that the BIAS must set to 10mV between the collectors (Indicated with TP1 and TP2 on the PCB).
Hirkc7 said:
I have a DENON POA 6600 A that needs output transistor replacement.
The original parts are Sanken 2SC3856 and 2SA1492.
After reading all the posts, I believe that in the DENON case I should not try any replacement and stick to the original ones (This amp has a optical bias setup circuit based on very tight tolerances).
Can you help me find some ?
Best Regards
Ricardo
Hirkc7 said:
I have a similar problem trying to find alternatives to 2SA1492 / 2SC3856.
Fortunatelly and thanks to you I now know of two possible alternatives:
Alternative 1 - 2SA1294 / 2SC3263
Alternative 2 - 2SA1386 / 2SC3519/A
Can you please advise as I am not at ease with the datashhets ?
I want the maximum speed even if I loose some power (that I do not need).
Best Regards
Ricardo
I have also a Samson S1000 amplifier, and I need the same components. Where can I get these in Holland? I would like to contact AudioJohny but unfortunately I am not able to mail, because I am new on this forum.
Greetings,
Rob
Greetings,
Rob
Hello Rob. You are the next victim! When will the pain stop??!! 😉
The answer on your question:
I didn't know for sure, but i thought i used the 2SA1294 and 2SC3263. The 2SC3856 and 2SA1492 where also used in my Yamaha P1600 amplifier, i replaced this with the 1294 and 3263 and this works fine! If you need, i've got an service manual of this amplifier.
The answer on your question:
I didn't know for sure, but i thought i used the 2SA1294 and 2SC3263. The 2SC3856 and 2SA1492 where also used in my Yamaha P1600 amplifier, i replaced this with the 1294 and 3263 and this works fine! If you need, i've got an service manual of this amplifier.
For real genuine Sansui parts, also 2SC3856 look here:
http://stores.ebay.de/Incredible-Pins-and-Parts
http://stores.ebay.de/Incredible-Pins-and-Parts
Hey im also looking for this Transistor C3856 03Y Sankin. I need them for a sony stereo receiver. I want to replace all four and a couple of resistors. If you already found them let me know where so i can get them. Thanks in advance!
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