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Old 1st October 2006, 06:34 AM   #11
wayle45 is offline wayle45  United States
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Unhappy Threshold S300 ll

This amp seems to lack smoothness or ease of delivery. While checking the bias, I noticed a number of power transistor replacements. They read MJ15011. 10 amp, npn, bipolar. This bank shows lower output than the other. Is this the correct substitution for the S300 "stasis" ? Could this cause nonlinearities in the amplifier output? I think the amp is worth a fix. Thanks, Wayne
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Old 3rd November 2006, 06:29 PM   #12
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Location: Sofia
Default S300 Series II

I wonder if anyone still remembers ( ) what type the 1ohm emitter resistors are. Carbon composition? Brand? Some of them are cracked on mine.

Initial audition was not too promising but there is plenty of good metal to be reused Very tempted to replace the PS Mallory with something civilised...
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Old 3rd November 2006, 08:06 PM   #13
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They were IRC wire-wounds. You can sub the Panasonic
3W metal films without problems.

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Old 3rd November 2006, 08:09 PM   #14
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Default Re: Threshold S300 ll

Quote:
Originally posted by wayle45
They read MJ15011. 10 amp, npn, bipolar. This bank shows lower output than the other. Is this the correct substitution for the S300 "stasis" ? Could this cause nonlinearities in the amplifier output? I think the amp is worth a fix. Thanks, Wayne
While these will function, you want the MJ15024 - 27 series
which work better.
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Old 4th November 2006, 04:36 AM   #15
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Quote:
Originally posted by Nelson Pass
They were IRC wire-wounds. You can sub the Panasonic
3W metal films without problems.


Many thanks Mr Pass. If they are indeed wirewound i may just live with the cracks.
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Old 13th December 2009, 08:16 AM   #16
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Default SA/12e and S/550e

Hi,
Does anyone know parts different between SA/12e and S/550e ?

I try to reduce S/550e bias but I still can't do it ! (now 125mA/transistor and I need only 25mA/transistor)

P.S. I don't have S/550e schamatic but I have only SA/12e schematic on hand :-)

Thanks
Anadigit
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Old 30th August 2010, 05:57 PM   #17
nhojaji is offline nhojaji  United States
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Hello, can someone send me the s300-II power supply and the main board schematic?
Is there a part list with detail information available for this amp?
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