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2SC1000 BL, 2SA493 GR Modern replacements
Old 29th May 2017
  #1
2SC1000 BL, 2SA493 GR Modern replacements

2SC1000 BL, 2SA493 GR Modern replacements..
I've been scouring about , following the family tree of obsolete D sheets..
I hoping someone can help me out with a possible upto date drop in?
less noise is always better..
thanx for any info..
Old 31st May 2017
  #2
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From a quick googling of the original data for those, I'd be reaching for one of the higher-gain-grades of 2SC945/2SA733. I frequently use the Fairchild equivalents in design (KSC945/KSA733), as they're very consistent and have SMD equivalents (FJX945/FJX733). In TO-92, they're available in both the "American" pinout (EBC) as well as the "Japanese" pinout (ECB). So for your case a direct swap would be KSC945CG and KSA733CG.
Old 14th August 2020
  #3
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hnbcstudios's Avatar
 

Quote:
Originally Posted by kirkus View Post
From a quick googling of the original data for those, I'd be reaching for one of the higher-gain-grades of 2SC945/2SA733. I frequently use the Fairchild equivalents in design (KSC945/KSA733), as they're very consistent and have SMD equivalents (FJX945/FJX733). In TO-92, they're available in both the "American" pinout (EBC) as well as the "Japanese" pinout (ECB). So for your case a direct swap would be KSC945CG and KSA733CG.
Hi,
I'm working on an early Soundcraft mixer that uses these same exact two transistors. I have found some KSC945CG and KSA733CG replacements as suggested. I take it these are the ECB version as I have original Toshiba units in the board.
Two questions:
First dumb one: if I for whatever reason ended up with EBC versions I could just twist the legs, right?
Second: Any other pairings that are not terribly obscure that might be worth looking into?
These things are everywhere in this board from mic preamp to line amps. I think originally in the PS too.
Mainly I'm just looking for a little bit better noise spec and hopefully decent reliability.
JP
Old 14th August 2020
  #4
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analogguru's Avatar
 

2SC1000 is a very low-noise transistor which can't be replaced by an el cheapo 2SC945 - take a 2SC2240 (2SC2547 or 2SC3198) instead. For the 2SA493 take a 2SA970 (2SC1085 or 2SC1048).
Old 14th August 2020
  #5
For 2SC1000 I use Toshiba 2SC3329BL, much lower noise. For 2SA493 I use 2SA1084 made by Hitachi or Renesas.
Old 16th August 2020
  #6
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hnbcstudios's Avatar
 

hFE

Quote:
Originally Posted by Jim Williams View Post
For 2SC1000 I use Toshiba 2SC3329BL, much lower noise. For 2SA493 I use 2SA1084 made by Hitachi or Renesas.
I am listening!
Both of you.
Thank you for redirection and reiteration.

I'm forced back into contemplation of this right now because a couple of channels in the Cue section of the Soundcraft are getting 'snowy'.
Since I am going to work on that and the fact that I'm going back into all 16 channels to change out the input pots I figure I should at least try a few mods or upgrades on at least few channels while I'm in there.

In trying to get a grip on transistor specs and their symbols I noticed the hFE classifications: BL being the higher range for the 2SC3329(and 2SC2240) and E being the higher class of 2SA1085(and 2SA1085). These being the gain multiplier, I figure this is not to be ignored.
I noticed that the original PNP (2SA970) is not of the higher class of hFE. Would that be on purpose, or just...'that was what we had back then!'

My first question is, and it may be stupid, to what degree should I stress this factor in my application?
I found a large stash of NPN's that are in the middle range of hFE. Bad Idea?
I should stay at the upper range? Right? Or might I hurt a circuit that doesn't want to see that kind of gain? Just keep the PNP and NPN relatively in the same range?
There are roughly 180 NPN and PNP's in the board, so I don't want to start with a terrible move, although I'm sure I'll blow something up this month.
I understand it's likely going to be different depending on what and where in the circuit(s).

I also understand if the answer is too long to get into.
Or, "Just use what I said and shut up".
I'm learning, very slowly.
Thanks

Last edited by hnbcstudios; 16th August 2020 at 06:56 AM..
Old 16th August 2020
  #7
2SC2240 and 2SA970 are general purpose transistors, not the low noise stuff. Those parts are used in Soundcraft consoles in the power supply tracking and headphone driver stages.
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