Substitute for 2SC458?

RosserClark

Active Member
In my quest to fix my 2000x, I am replacing the 2SC458s. The 2SC2240 was recommended, and I was going to get them, but Mouser is the only place I could find them, and they won't get any in stock for 6 weeks. They recommended another replacement type, but they were over $2 each, where the 2240s were 17 cents. Is there another replacement for the 458s? Or another place to get the 2240s? Thanks
 
I found this quote from a thread by jpdylon, a really good tech.

"While you're in here, look at the initial audio amp transistor near the input leads of the board. if its a 2sc458 REPLACE IT. These transistors are notorious for becoming noisy and opening. This will cause all sorts of pink noise and crackling. Replace it with a 2sc631 or 2sc2240. I prefer the later for its low noise and low leakage characteristics"


Hope this helps.

Not the same gear you're working on, but the thread is here.
 
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Don't worry, virtually every transistors are better than the 2SC458.

The KSC1845 previously suggested is perfect too.

I don't know why they called the 2SC458 a low noise transistor since the noise contour map of the 2SC458 shows that it is much noisier than many transistors. For example, the common 2SC945 is much better.
 
I went to a local Electronic store in order to change my 2sc458 trans... They told me that the 2240 are not longer available and that a good replacement is the japanese 2sc1313... What do you think? Is that a good replacement? What about noise performances?
 
I went to a local Electronic store in order to change my 2sc458 trans... They told me that the 2240 are not longer available and that a good replacement is the japanese 2sc1313... What do you think? Is that a good replacement? What about noise performances?

The 2SC2240, from the link above:

 
In the units where I've replaced the 2sc458's, (2-2000A, 2000X, 3 different AKAI R2R) I took one of the AKAI's and replaced one side with 1845's and one with 2240's. The noise floor on the 2240 is a bit better (I don't have any test gear) than the 1845. Having said that, the 1845 is easier to find and is available most everywhere. The 2240 has been discontinued by the manufacturer, so if you DO find them, stock up. But for general repairs and something that is for background listening the 1845 is fine.

Larry
 
Another question about replacing these: My Sony TC-K96R has 8 of them and the service manual states,"for replacement use semiconductors except in ( )" and the darn 2sc458's (bottom) are in the parentheses? Are they candidates to be replaced with 2sc2240's, BC549's or KSC1845's?

semi.jpg
 
I have been using 2SC1815's for many years, and they always work well. They are specifically a "low noise audio transistor" with similar specifications to the 2SC458.

Be aware the pinout is backward from most 2SC458's


They actually come in different HFE ranges. I use the 2SC1815 GR which has an HFE range between 200 and 400. I buy them by the 100 lot, and spot checking HFE they all come out around 300 (+- 10 or 20)

https://alltransistors.com/transistor.php?transistor=12413
 
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Interesting, I just pulled the Qx08-x09's (4, both channels) out of a Sony TC-K96R and they are actually 2SC945's! They are spec'd as 2SC1364 (2SC458) in schematic Were these replaced already? They look about as old as everything else in here.....running change? 3 of the '945's measured HFE of 289 and one measured low at 230.....1 of the 6 2SC1345's had a low HFE of 421 while the rest were 455-465 range. Time for a buy.....
 
Check the specs on the KSC1815Y, you will find they exceed the specs of the original 2SC485. Currently they are only made (best I could locate) with the Y - hFE range (120-240). I recently used them on a 777A upgrade. Ditg-Key sells the ON Semiconductor version (part # KSC1815YTACT). On the issue of gain, my parts tested out with a gain of 210 which exceeds the 2SC485 B level (100-200) and is in the C level (160-320). Best part is the noise level at 1dB vs 4-10dB for the 485. In general a better replacement than the 1845.

BTW - would be interested in a source for the GR level - but for this upgrade the Y's worked fine and were in spec to the originals
 

I don't feel especially qualified to comment on whether it can be a sub for 2SC458, but it's an interesting part - thanks for pointing it out. It might go without saying, but watch out for the Zetex part's center-base pinout. It's interesting that the Vceo is only 40V (which is more than the 2SC458's, so no problem there with regard to substitution). But the Vcbo is 150V!
 
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