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Old 18th January 2013, 05:43 AM   #1
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Default Need advice for Output Transistors

I have an Onkyo M504 with the complimentary pair 2SA1492, 2SC3856. I am looking for outputs that can take more abuse without losing too much speed. Any ideas? I upgraded the drivers to 2 amp devices.
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Old 18th January 2013, 02:38 PM   #2
Aniket is offline Aniket  India
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Hi,

for TO-3P devices go for NJW0281,0302(150W) from Onsemi, or 2SC6011,SA2151(160W) from Sanken for output devices.
for drivers go for 2SC4793, 2SC5171 from Toshiba or 2SC4832 from Sanken.
Just an advice.

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Aniket
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Old 18th January 2013, 02:42 PM   #3
mos57 is offline mos57  Italy
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(MT-100)2SC3281/2SA1302; 2SC3263/2SA1294;

(MT-200)2SC3858/2SA1494;2SC2921/2SA1215;2SC3264/2SA1295;

Francesco.
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Old 18th January 2013, 04:47 PM   #4
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Thanks Aniket. The On Semi's I can obtain easily. Does On Semi make any stout drivers in TO220 package that you know of?
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Old 18th January 2013, 05:10 PM   #5
Aniket is offline Aniket  India
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Onsemi's MJE15031/30(150V,50W), MJE15032/33(250V,50W) and MJE15034/35(350V,50W) should work well with NJW0281,0302. With +/-67V rails, better use MJE15032/33.

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Aniket
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Old 18th January 2013, 06:27 PM   #6
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The current substitute drivers I have are 2SA1606 which replaced 2SA1306. These are an insulated TO220 device meaning they are plastic/composite housing and are bolted to the heat sink. For the life of me what is the purpose of 2SA3419 in the circuit. Protection device??
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Old 19th January 2013, 08:26 AM   #7
Aniket is offline Aniket  India
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Maybe for thermal compensation

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Old 19th January 2013, 10:16 AM   #8
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The 2SC3856/1492 Sankens are actually my-t-tuff! The chips are similar to those in the larger 2SC3858/1494 pair and anyone who used those would know that the MJ_3281/1302 series parts are not rated up to that 200W level. Can you physically accommodate larger sized transistors? You only need the larger case size if dissipation is high enough to warrant it but then you need more heatsinking too. SANKEN ELECTRIC : Power Transistors : For Power Amplifier

Unless you are just trying to increase the output power rating of the amplifier, this is not the way to toughen it against mishandling, shorts or very low impedance speakers. In the latter case, you need to consider another amplifier design with multiple output devices. Otherwise, the amplifier needs an overhaul to get the overload protection working properly. You will blow any reasonable alternatives just as easily as the original parts, if this is going to be your strategy.

Adding insult, the excellent Sankens with their original drivers will eat most substitutes soundwise, unless some careful work goes into selection.
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Old 21st January 2013, 08:48 AM   #9
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My intentions was to replace all the output devices due to a a failed output transistor. The circuit board was cracked, this was the cause. I have obtained some On Semiconductor MJL4281A's with the complimentaries and On semis MJW0821G with it's complimentaries. Which pair would you recommend..One is rated for 150W and the others are rated for 230W. I chose to use On Semis cause the are Genuine non fakes. They are substitutes so what problems could I run into??? Is oscillation possible???
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Old 21st January 2013, 09:02 AM   #10
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Also I can accomodate TO264's... which are slightly longer than TO3P
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