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Sx-850 transistor components shortage options?...

T

Truetone

New Member
Hello to all AK members! I am a big fan but have never posted. I am a reader of old threads and try to educate myself the best I can...I have the ambition of tackling a restoration project for different reasons, first and foremost, diving in is I think the best way to focus on learning, second
I am someone who repairs(try) anything vintage as I am now also of the same era!
And lastly the sx850 is my dream amp because when I was a kid I was only allowed to look at it and listen but never to touch it!! Ha ha now that I have found one I feel it's my chance ;)
Sorry for that long intro ... I have summed up all necessary info and parts list and was getting ready to order a cart from Digikey but they would seem to be out of two prefered transistor replacement for my power supply board (awr-101)

Q1,Q8 & Q9 : sd313p >>mje15032g <<

Q5 : 2sc1318 >>ksc2690ays<<

I have found Dlucy's thread on choosing replacement transistors but feel I am turning in circles as each time I feel (half) confident I have found a candidate it turns out to be also out of stock...hence I turn to you AK'ers and to your bottomless pit of knowledge and experience ....

PS: please excuse my poor English as it is not my first language...I wish your cringes where semi-smiles
Thanks in advance for your consideration!
 
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Truetone said:
Hello to all AK members! I am a big fan but have never posted. I am a reader of old threads and try to educate myself the best I can...I have the ambition of tackling a restoration project for different reasons, first and foremost, diving in is I think the best way to focus on learning, second
I am someone who repairs(try) anything vintage as I am now also of the same era!
And lastly the sx850 is my dream amp because when I was a kid I was only allowed to look at it and listen but never to touch it!! Ha ha now that I have found one I feel it's my chance ;)
Sorry for that long intro ... I have summed up all necessary info and parts list and was getting ready to order a cart from Digikey but they would seem to be out of two prefered transistor replacement for my power supply board (awr-101)

Q1,Q8 & Q9 : sd313p >>mje15032g <<

Q5 : 2sc1318 >>ksc2690ays<<

I have found Dlucy's thread on choosing replacement transistors but feel I am turning in circles as each time I feel (half) confident I have found a candidate it turns out to be also out of stock...hence I turn to you AK'ers and to your bottomless pit of knowledge and experience ....

PS: please excuse my poor English as it is not my first language...I wish your cringes where semi-smiles
Thanks in advance for your consideration!
Click to expand...
Have you checked with AKer EastPoint?
 
Thank you Markthefixer(you're a legend in my book!) For confirming KSD526 the 8mhz seems to be closer to the 2sd313 ....(I remember you mentioning this in one of your old post )
As for the KSD2690AYSTU would it get your approval in Q5 (awr-101)?

And as for a last question if I may...
I see in my notes that ksc2383yta is suggested instead of ksc2690ay in replacement of 2sc1318 in Q7
What could be the reason of this...if any?

(Thank you all for helping me waking up tomorrow a little bit wiser)
 
Transistors are happier, work more predictably and live longer when they are run cool.

The KSC2690AYSTU gets my approval in Q5 (awr-101).
It was cooking the original 2sc1318...
Q5 is shedding 0.75 watt, the to-126 case can shed about a watt unaided. 10 watts heat sunk.
It will get warm UNLESS the case has a heat sink (which it is both able to accept
AND as a bonus it exposes NO voltages to the heat sink),
a ksc2383yta would still be swamped by the heat load.

The ksc2383yta is a larger package size than the 2sc1318.
The ksc2690ay is an even larger package size then the 2sc1318.

Q7 is the +28v regulator, which only powers the phono preamp (along with the -19v supply) ,
with a 0.0097 amp power draw (9.7mA) using a 7v drop, that's about 0.072 watt.
not a lot of heat. the ksc2690ay could be considered overkill.
The ksc2383yta is prudent, fault conditions could obliterate the 2sc1318.
 
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Wow mark! knowledge never rests!! (12.20am!!)Your answer really overwhelmed my expectations and so I wake up taller standing on shoulders of giants!

My order is processing at Digikey (I feel like a kid the week before Christmas ) I will post a picture of my operating table once the patient is ready for transplant
Keep on clutching!

Thanks
 
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