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2SA847 substitution info

xoaphexox

xoaphexox

Supernatural Anesthetist
Looking for info on the TO-92 2SA847 transistor being used as a differential input in a friends Mitsubishi DA-A10DC. Can't find any info here on this forum about people using subs but here is the info I pulled from the datasheet word docs EW shared with us:

Type
p-n-p

Vceo
90V

Ic
50mA

Pc
200mW

B
250

Ft
150

I am wondering if the KSA992 will work here - it looks like it may, but its 50MHz slower concerns me: http://www.fairchildsemi.com/ds/KS/KSA992.pdf

Does anyone know of a more suitable replacement?

Thanks!
 
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Here ya go brutal, had to dig this up recently myself looking for subs:

http://www.audiokarma.org/forums/showthread.php?p=1655960

And xoaphexox, I wish I could help. I've been looking for subs for almost every transistor on the amplifier boards in my Optonica SA-5151, all of them obsolete. B&D had all of them except a couple, for which they had some suggested substitutes. Your 2SA847 is nowhere to be found though... What I would like to know is, what values can you fudge on when it comes to finding a good replacement? We ubiquitously substitute caps with higher voltages all the time, and sometimes higher capacitance like in power supplies. I'm sure it depends on the application, but I would think there is at least a spec or two where it is probably OK to go a little higher (or lower), but I'm not sure about frequency.
 
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xoaphexox said:
Looking for info on the TO-92 2SA847 transistor being used as a differential input in a friends Mitsubishi DA-A10DC. Can't find any info here on this forum about people using subs but here is the info I pulled from the datasheet word docs EW shared with us:

Type
p-n-p

Vceo
90V

Ic
50mA

Pc
200mW

B
250

Ft
150

I am wondering if the KSA992 will work here - it looks like it may, but its 50MHz slower concerns me: http://www.fairchildsemi.com/ds/KS/KSA992.pdf

Does anyone know of a more suitable replacement?

Thanks!
Click to expand...
Identical specs..And bdent's got'm----a little pricey though. @ $2 apiece.
http://www.bdent.com/specifications/2SA904.PDF
 
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You'll find complete specs here.

Here's a table which gives the MPS-8799 as closest sub.

Some other page give other references:
On this page you'll find that 2SA847 = 2SA872(a), 2SA941, 2SA942, 2SA970, BF435, BF491, BF493, BFP 23, BFP 26, MPSA 92, MPSA 93

Also 2SA1124 on this page.


Hope this helps !
 
:lmao: That sounds awfully familiar... My first order, I ordered 4 2SC971's because that's what got me to the magic number, and I figured I might as well grab some spares. Luckily (or unluckily) my last order was passed the figure by quite a bit.
 
avionic said:
Identical specs..And bdent's got'm----a little pricey though. @ $2 apiece.
http://www.bdent.com/specifications/2SA904.PDF
Click to expand...

Great - I will bookmark that. Not sure whether to buy them or not - this is for the Mitsubishi thread that you commented in yesterday. I still haven't found the source of the issue. I replaced two failure-prone diodes and it hasn't helped.

I may try to find a few more subs for other transistors in the amp and place an order. If I replace all the transistors I assume the problem will be solved, lol.
 
I ordered 10 of those transistors too.

le greque said:
:lmao: That sounds awfully familiar... My first order, I ordered 4 2SC971's because that's what got me to the magic number, and I figured I might as well grab some spares. Luckily (or unluckily) my last order was passed the figure by quite a bit.
Click to expand...
 
laatsch55 said:
Bad assumption, xoaphexox.
Click to expand...

'Lol' implies a joke, but in seriousness I replaced all the caps and the diodes and resistors test good. There aren't any other parts in this unit but transistors (and relays which were also replaced). Can you share with me what you believe will fix my problem?
 
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