Which replacement transistor for Sanken C3856/A1492? - Page 3 - diyAudio
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Old 19th February 2007, 02:44 PM   #21
rkc7 is offline rkc7  United States
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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.
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Old 19th February 2007, 03:16 PM   #22
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Quote:
Originally posted by rkc7
The schematic is too large to attach to the board, so I uploaded it to a schematic website. You can get it here:

http://www.eserviceinfo.com/download...son_S1000.html

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?
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Old 19th February 2007, 04:40 PM   #23
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Quote:
Originally posted by rkc7
equivalents for the original output transistors
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.
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Old 20th February 2007, 05:33 AM   #24
rkc7 is offline rkc7  United States
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Quote:
Originally posted by MatchASM



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?
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.


Quote:
Originally posted by jacco vermeulen



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.
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.
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Old 20th February 2007, 09:15 AM   #25
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Originally posted by rkc7
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.
In that case, make it the SOURCE terminals (what was I thinking writing DRAIN?).
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Old 19th March 2007, 03:31 AM   #26
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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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Old 19th March 2007, 04:28 AM   #27
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Tell me at what points you want measured for what, I'm not sure what "idle settings" measurements are.
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Old 19th March 2007, 11:07 PM   #28
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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...
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Old 20th March 2007, 12:39 AM   #29
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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?
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Old 20th March 2007, 01:19 AM   #30
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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!
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