-
Feeling lucky? Check out the AK 24th Anniversary Giveaway thread and join in the fun!
transistors substitions
- Thread starter calman46
- Start date
Register to hide this ad
2SC1669 http://www.bdent.com/search/part.jsp?partnum=2SC1669 TIP47 SUBS
2SC1904 http://www.bdent.com/search/part.jsp?partnum=2SC1904
2SD608 http://www.bdent.com/search/part.jsp?partnum=2SD608 TIP47 SUBS
2SD761 http://www.bdent.com/search/part.jsp?partnum=2SD761 TIP47 SUBS
http://www.onsemi.com/PowerSolution...SD608&searchType=xref&tabbed=Y&clearFilters=Y
2SC2441 http://www.fairchildsemi.com/crossref/crossrefSearch.do KSC2310 SUBS
2SC1904 http://www.bdent.com/search/part.jsp?partnum=2SC1904
2SD608 http://www.bdent.com/search/part.jsp?partnum=2SD608 TIP47 SUBS
2SD761 http://www.bdent.com/search/part.jsp?partnum=2SD761 TIP47 SUBS
http://www.onsemi.com/PowerSolution...SD608&searchType=xref&tabbed=Y&clearFilters=Y
2SC2441 http://www.fairchildsemi.com/crossref/crossrefSearch.do KSC2310 SUBS
Last edited:
Drivers and pre-drivers?
2SC1904A (TO-126) >150Vceo, 50mA, 1W, B=150, ft=130MHz
2SA899A (TO-126) >150Vceo, 50mA, 1W, B=150, ft=100MHz
2SD608A (TO-220) >160Vceo, 1.5A, 20W, B=80, ft=45MHz
2SB628A (TO-220) >160Vceo, 1.5A, 20W, B=80, ft=40MHz
All of these are 'A' variants, so the voltage rating should be higher than the non-A part. Anyway, the TO-220 driver is easy...use the MJE15032 and 15033 for the drivers. Personally I think these are a better choice than the 15034/35, as the high-voltage capability is not needed.
The hard choice is replacing the C1904A & A899A. A lot of good TO-126 parts went away in the last year.
Best Choice - Fairchild KSA1142 & KSC2682. Since these are damn hard to find, the Sanyo 2SA1210 and the 2SC2912 are a couple of the last decent low-current wide-bandwidth TO-126 parts left. B&D has them.
2SC1669 is too slooooooowwwwwwwwwwwww.
2SC2441 (TO-126??) has nice specs, but what's its complement? If the amp blew, you change not just the NPN, but the PNP too.
2SC1904A (TO-126) >150Vceo, 50mA, 1W, B=150, ft=130MHz
2SA899A (TO-126) >150Vceo, 50mA, 1W, B=150, ft=100MHz
2SD608A (TO-220) >160Vceo, 1.5A, 20W, B=80, ft=45MHz
2SB628A (TO-220) >160Vceo, 1.5A, 20W, B=80, ft=40MHz
All of these are 'A' variants, so the voltage rating should be higher than the non-A part. Anyway, the TO-220 driver is easy...use the MJE15032 and 15033 for the drivers. Personally I think these are a better choice than the 15034/35, as the high-voltage capability is not needed.
The hard choice is replacing the C1904A & A899A. A lot of good TO-126 parts went away in the last year.
Best Choice - Fairchild KSA1142 & KSC2682. Since these are damn hard to find, the Sanyo 2SA1210 and the 2SC2912 are a couple of the last decent low-current wide-bandwidth TO-126 parts left. B&D has them.
2SC1669 is too slooooooowwwwwwwwwwwww.
2SC2441 (TO-126??) has nice specs, but what's its complement? If the amp blew, you change not just the NPN, but the PNP too.
That's a rather extreme position to take with parts that are very difficult to source. If you want to start replacing rare components 'just because', be sure to ship the old ones to me.
Calman, unless you break the leads off of them, these multijunction diodes rarely fail. You can test them with a multimeter diode test if yours happens to supply enough voltage to get the job done.
Calman, unless you break the leads off of them, these multijunction diodes rarely fail. You can test them with a multimeter diode test if yours happens to supply enough voltage to get the job done.
I believe I bought mine from encompass- STV4's were $4.99 a piece\
the STV3's were more expensive at around $10-$11.00 a piece.
But as you are aware, the leads on those are pretty fragile after all of these years. I guess it was $30.00, but for me, well worth it.
Actually, against all advice, I also replaced pretty much every component on both amp boards, including the resistors (did not replace one transistor).
Was it needed - no, but for the total cost (varistors were most expensive thing besides filter caps) , bias could not be better, runs really cool, and as all the components on the amp boards are new, I am hoping it will be another 20+ years before I take a soldering iron to it again.
While the resistors were all still in tolerance, you could see the effects of 30 years of heat on them. I hopefully vastly reduced the chance of a component failure on my amp boards.
Besides the varistors, was really cheap. The boards were already out so basically took no time and I understand that it probably makes no difference, but is nice knowing I have all 1% resistors in there.
But, I did preface all of this by saying, I am by no means an expert, in fact, as far from one as you could get as my forgetting the insulators on the heat sink can attribute.
I just like seeing it sitting there knowing she is full of brand new components.
Sure sounds good anyway.
If I ever happen to stumble on another Spec 2, i will do the same thing to it, and I will go ahead and send you the old varistors.
the STV3's were more expensive at around $10-$11.00 a piece.
But as you are aware, the leads on those are pretty fragile after all of these years. I guess it was $30.00, but for me, well worth it.
Actually, against all advice, I also replaced pretty much every component on both amp boards, including the resistors (did not replace one transistor).
Was it needed - no, but for the total cost (varistors were most expensive thing besides filter caps) , bias could not be better, runs really cool, and as all the components on the amp boards are new, I am hoping it will be another 20+ years before I take a soldering iron to it again.
While the resistors were all still in tolerance, you could see the effects of 30 years of heat on them. I hopefully vastly reduced the chance of a component failure on my amp boards.
Besides the varistors, was really cheap. The boards were already out so basically took no time and I understand that it probably makes no difference, but is nice knowing I have all 1% resistors in there.
But, I did preface all of this by saying, I am by no means an expert, in fact, as far from one as you could get as my forgetting the insulators on the heat sink can attribute.
I just like seeing it sitting there knowing she is full of brand new components.
Sure sounds good anyway.
If I ever happen to stumble on another Spec 2, i will do the same thing to it, and I will go ahead and send you the old varistors.
I've repaired two dozen or more blown Spec 2's and probably a dozen blown Spec 4's, and have yet to see a dead mj-diode. So unless you think yours blew in some new and novel fashion, they are probably just fine.
Donberry, if you have a part number for the device, I'd love to have it. Encompass is a huge conglomerate of various companies, so a url to where you found them would be cool too.
I bought the STV3's from partstore.com. Actually, if I am not mistaken, you are the one who pointed me there.
When I bought mine, they were the Kenwood STV3H-Y. I just looked on their site tho and they no longer have those, but they do have the JVC STV3 - is the only one left.
I can not remember where I got the STV4's from. I only paid $4.95 a piece for those. Partstore has them, but cheapest ones they have are $9.95 a piece.
But, now this is just me and as you well know, I am like a blind man leading his guide dog - even at $45-$50.00 , if I ever lucj into another Spec 2 and the wires on the old ones are fragile as they are apt to be after 30 years of heat - I would still go ahead and replace them at that price (i would search around and see if I could find those $4.95 ones tho).
i understand that the old ones are probably fine but for me, this is a keeper amp that i will probably have until I die or am committed , so as long as I have the amp boards out, I would go ahead and spend the $50.00 just for piece of mind.
I would imagine it probably would have been the same whether I replaced all that stuff or not, but I am no longer that worried about a component failure on the amp board (famous last words) and , again, may have been the same if I did not do it, but with all new components and your RL1 repair procedure, the adjustments are spot on, runs surprisingly cool when I run the maggies at loud volume (the amp gets a good workout on those) , meters no longer jump when powered off and I have nothing else to really compare it to, but it sure sounds good to me.
Basically i just scoured every post you ever wrote about it and did everything you have ever mentioned with the only difference being I replaced all the transistors (except one) and resistors with 1% tolerance whether they were in spec or not.
I am sure that there are extra little tweaks that you do that would make it even better then it is,and mine is not nearly as "pretty" as an echo amp would have been, but thanks to all of the information that you have so kindly shared, all things considered, I am pretty happy with it.
If only I did not forget those stupid insulators it would have actually been a pretty straight forward repair job. Not only did it really throw me as I was thinking I put a NPN in where i should have used a PNP, something about watching my amp boards resemble a Tesla coil was kind of scary.
When I bought mine, they were the Kenwood STV3H-Y. I just looked on their site tho and they no longer have those, but they do have the JVC STV3 - is the only one left.
I can not remember where I got the STV4's from. I only paid $4.95 a piece for those. Partstore has them, but cheapest ones they have are $9.95 a piece.
But, now this is just me and as you well know, I am like a blind man leading his guide dog - even at $45-$50.00 , if I ever lucj into another Spec 2 and the wires on the old ones are fragile as they are apt to be after 30 years of heat - I would still go ahead and replace them at that price (i would search around and see if I could find those $4.95 ones tho).
i understand that the old ones are probably fine but for me, this is a keeper amp that i will probably have until I die or am committed , so as long as I have the amp boards out, I would go ahead and spend the $50.00 just for piece of mind.
I would imagine it probably would have been the same whether I replaced all that stuff or not, but I am no longer that worried about a component failure on the amp board (famous last words) and , again, may have been the same if I did not do it, but with all new components and your RL1 repair procedure, the adjustments are spot on, runs surprisingly cool when I run the maggies at loud volume (the amp gets a good workout on those) , meters no longer jump when powered off and I have nothing else to really compare it to, but it sure sounds good to me.
Basically i just scoured every post you ever wrote about it and did everything you have ever mentioned with the only difference being I replaced all the transistors (except one) and resistors with 1% tolerance whether they were in spec or not.
I am sure that there are extra little tweaks that you do that would make it even better then it is,and mine is not nearly as "pretty" as an echo amp would have been, but thanks to all of the information that you have so kindly shared, all things considered, I am pretty happy with it.
If only I did not forget those stupid insulators it would have actually been a pretty straight forward repair job. Not only did it really throw me as I was thinking I put a NPN in where i should have used a PNP, something about watching my amp boards resemble a Tesla coil was kind of scary.
