I am having problems finding genuine 2SA992/2SC1845, 2SA1145/2SC2705, 2SA1306/2SC3298 , and some other ones. I trust ebay as much as a tuna sandwich from a gas station vending machine when it comes to authenticity of merchandise. Unless someone knows a reliable source and would be kind and point me in the right direction.
What do I look for in finding replacements? What is important? What should be prioritized? Ft, Cc, Ic, Vcb, Vce, hFE are some of the perimeters besides that the transistor has to fit on the PCB. I am trying to bring life back to a Sansui B2102 if it matters.
I've spent some time on this now and I don't feel confident in the replacements suggested that I find as most of those are now obsolete as well.
What do I look for in finding replacements? What is important? What should be prioritized? Ft, Cc, Ic, Vcb, Vce, hFE are some of the perimeters besides that the transistor has to fit on the PCB. I am trying to bring life back to a Sansui B2102 if it matters.
I've spent some time on this now and I don't feel confident in the replacements suggested that I find as most of those are now obsolete as well.
I must admit to using ebay once for obsolete stuff but I never drove the amp hard to find out if it was reliable or not.
My experiences with Chinese suppliers has been mostly very poor.
I think you need to sit down with transistor data sheets and work out some modern replacements.
Even this can be a minefield as I have replaced old 2n3055 with modern 2n3055's and the amp has oscillated due to higher ft of modern version.
The fix was to increase VAS capacitor until oscillation went.
On a different amp this didnt work and I had to put in 10R base stopper on output transistors.
Its certainly a game.
My experiences with Chinese suppliers has been mostly very poor.
I think you need to sit down with transistor data sheets and work out some modern replacements.
Even this can be a minefield as I have replaced old 2n3055 with modern 2n3055's and the amp has oscillated due to higher ft of modern version.
The fix was to increase VAS capacitor until oscillation went.
On a different amp this didnt work and I had to put in 10R base stopper on output transistors.
Its certainly a game.
KSA992 and KSC1845 from Mouser or Digikey are modern On Semi replacements for the Toshiba 2SA992 and 2SC1845.
2SA1145 Toshiba is available from B&D Enterprises in your country.
2SC2705 is just about unobtainable - but the 2N5551C is an equivalent, should be found at Mouser or Digikey.
2SA1306 is replaced by the 2SA1606 Sanyo at B&D.
2SC3296 is replaced by the 2SC4159 Sanyo at B&D.
Hope that helps.
2SA1145 Toshiba is available from B&D Enterprises in your country.
2SC2705 is just about unobtainable - but the 2N5551C is an equivalent, should be found at Mouser or Digikey.
2SA1306 is replaced by the 2SA1606 Sanyo at B&D.
2SC3296 is replaced by the 2SC4159 Sanyo at B&D.
Hope that helps.
Nigel, how modern is modern? I am asking as I have a load of those from PSU. I think there are 3 in each PSU and I have like 20 PSUs on the shelf that I saved when replacing some equipment at Target stores here in the US.
Thanks, Gary. It took me a while to find B&D's website.
I guess I ventured into a mine field with this amp.
Thanks, Gary. It took me a while to find B&D's website.
I guess I ventured into a mine field with this amp.
A majority of the transistors are shot. All Sankens are toast. Some resistors, well they are more than a resistor now as there is no continuity whatsoever. All caps are on order; Silmic, as nothing else would fit on the PCB. I don't know the history of it so I don't know what happened to it. I have its mate as well, C2102, and I hope it is in better condition.
As far as to fT, how important is that? I would imagine both NPN and PNP should be matching.
As far as to fT, how important is that? I would imagine both NPN and PNP should be matching.
Nigel made a good point and a practical one as regards ft , posters keep on being advised here ---uprate that old amp !! fit this 600beta / 1Ghz latest active device into your --70,s/80,s ( or earlier ) audio amplifier forgetting it was DESIGNED in those eras to use existing active devices .
The result ??-- that familiar smell and smoke of the output devices frying due to HF oscillation --"how important is ft BearWolf ??-- VERY important when working on OLD audio designs .
As Gary says a Sansui amplifier is well worth repairing .
25 years ago I bought a Sansui -AU-317-11 it was old then at a car-boot sale ( trunk sale ) ,I fitted into my flatscreen Philips TV --25 years later its STILL working well ( and so is the 42 inch TV ) - no parts replaced --try that with some modern slim .flashy amp ?
The result ??-- that familiar smell and smoke of the output devices frying due to HF oscillation --"how important is ft BearWolf ??-- VERY important when working on OLD audio designs .
As Gary says a Sansui amplifier is well worth repairing .
25 years ago I bought a Sansui -AU-317-11 it was old then at a car-boot sale ( trunk sale ) ,I fitted into my flatscreen Philips TV --25 years later its STILL working well ( and so is the 42 inch TV ) - no parts replaced --try that with some modern slim .flashy amp ?
Duncan, all the Sankens are toast as it is and I am not interested in getting oscillation and do it over again. The one suggested, 2N5551, and its mate 2N5401, are 300MHz and just going up 50% is making me nervous. I found some other that is 100MHz, KSC2310, but that one is just as hard to come by as originals. From what I read as long as the specs aren't lower than originals then it is a go. I am doubtful of this tho, and especially after another post that said these little devices work as fuses as well and getting something "too good" will bypass the safety margin.
One way or another I will get life back into this little thingy, but there is so much I don't know. Thanks for all help and suggestions.
One way or another I will get life back into this little thingy, but there is so much I don't know. Thanks for all help and suggestions.
I am not saying its impossible to fit more modern active devices but then you have to delve into the circuit and make changes to the compensation after seeing what type of compensation that particular designer has made .
Not all designers use D.Self,s version of 100pf and many use "distributed compensation " ( various active devices having small capacitors applied in feedback in different parts of the design) .
But you are simply looking for a "shoe-in " replacement and I find it hard to believe that manufacturers have stopped manufacturing low ft BJT,s in small to medium current designs .
Not all designers use D.Self,s version of 100pf and many use "distributed compensation " ( various active devices having small capacitors applied in feedback in different parts of the design) .
But you are simply looking for a "shoe-in " replacement and I find it hard to believe that manufacturers have stopped manufacturing low ft BJT,s in small to medium current designs .
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