Question about transistor replacement

CKeeler · 12th December 2009, 01:04 AM

Hi, I'm new here so I hope this is in the correct forum, if not can it be moved? Anyway, back to my question, I am in need of some 2SA939 transistors but they do not seem to be availabe anymore. Can somebody recommend me a replacement part number that will work in place of the 2SA939 and be close enough in performance that there is no audible difference? Thanks for any help and suggestions.

djoffe · 12th December 2009, 03:01 AM

According to a "Bipolar Transistors Cross Reference" from SGS-Thomson, MJE350 should cross pretty well...check a few basic things...NPN vs. PNP, as a sanity check...some Japanese references I saw made the basic voltage ratings look plausible...good luck...

CKeeler · 12th December 2009, 03:12 AM

Thanks! You know, those are cheap enough, so I'll just order a dozen or so and give it a shot. Thanks for the suggestion!!

Mooly · 12th December 2009, 06:41 AM

Are they used as part of a complementary pair NPN/PNP driver stage ?
If they are might be worth looking to replace as a pair MJE340/350
Old Jap transistors often fail open circuit base emmiter for some unknown reason.

CKeeler · 12th December 2009, 07:56 AM

Quote:

Originally Posted by Mooly

Are they used as part of a complementary pair NPN/PNP driver stage ?
If they are might be worth looking to replace as a pair MJE340/350
Old Jap transistors often fail open circuit base emmiter for some unknown reason.

Good idea, they are actually. The other ones in the circuit are still good, but would it be a good idea to change them anyway so that I have complementary pairs that are more similar?

Mooly · 12th December 2009, 04:09 PM

These are more up to date, a list I keep for reference,

12th December 2009, 01:04 AM	#1
CKeeler diyAudio Member Join Date: Dec 2009	Question about transistor replacement Hi, I'm new here so I hope this is in the correct forum, if not can it be moved? Anyway, back to my question, I am in need of some 2SA939 transistors but they do not seem to be availabe anymore. Can somebody recommend me a replacement part number that will work in place of the 2SA939 and be close enough in performance that there is no audible difference? Thanks for any help and suggestions.

12th December 2009, 03:01 AM	#2
djoffe diyAudio Member Join Date: Oct 2008	SGS THomSON says... According to a "Bipolar Transistors Cross Reference" from SGS-Thomson, MJE350 should cross pretty well...check a few basic things...NPN vs. PNP, as a sanity check...some Japanese references I saw made the basic voltage ratings look plausible...good luck...

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12th December 2009, 03:12 AM	#3
CKeeler diyAudio Member Join Date: Dec 2009	Thanks! You know, those are cheap enough, so I'll just order a dozen or so and give it a shot. Thanks for the suggestion!!

12th December 2009, 06:41 AM	#4
Mooly diyAudio Member Join Date: Sep 2007	Are they used as part of a complementary pair NPN/PNP driver stage ? If they are might be worth looking to replace as a pair MJE340/350 Old Jap transistors often fail open circuit base emmiter for some unknown reason.

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