Hi, I have started restoration of my Yamaha MX-50 and looking for a good quality replacement for this transistors in reasonable price. Please note there should be minimum 140 hFE (S hFE range). Prefer shipping from europe to avoid weeks of waiting for parts.
Regards, Frogeon
Regards, Frogeon
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Something more generic like BD140/BD139 may work. Mouser has the -16 parts in stock (100-250 hFE range)
I had to look for the same pin out plus the same bias ( that's a major point ) , the same collector current and wattage .
2SC3902 fits the bill --don't worry about the much higher maximum voltage and its partner - 2SA1507 -
https://www.onsemi.com/pub/Collateral/EN2101-D.PDF
They will slot in -E-C-B- tab to the bottom .
And yes they are available online.
2SC3902 fits the bill --don't worry about the much higher maximum voltage and its partner - 2SA1507 -
https://www.onsemi.com/pub/Collateral/EN2101-D.PDF
They will slot in -E-C-B- tab to the bottom .
And yes they are available online.
My data book shows Hfe bias as 100ma for the 2SD1681S.
2SC3902 is showing the same Hfe bias of 100ma but its Hfe range can go up to 400 , the 2SD1681S can go up to 280.
Not a great different --if you were prepared to accept -B-C-E there is a much bigger range to chose from but they would not be a simple slot-in fit.
2SC3902 is showing the same Hfe bias of 100ma but its Hfe range can go up to 400 , the 2SD1681S can go up to 280.
Not a great different --if you were prepared to accept -B-C-E there is a much bigger range to chose from but they would not be a simple slot-in fit.
So you are talking about hFE at one single current (100mA), instead of comparing load lines and comparing hFE vs Ic vs Temperature graphs.
Right so your choice of BD140 has the same graphs as 2SD1681S ?
Your Ic max is 1 amp , 2SD1681S is higher than that , you don't go backwards in spec you go forwards as near to the original as you can .
Every semiconductor data book for selecting equivalents gives a fixed current that you work to , in any case the range of Hfe is shown to vary within a range of currents its just not published in public equivalent books .
For the 2SD1681 in UK types like the BD range its BD135 not BD140 both in the Mullard book and the German ECA highly respected book used by electronic / TV etc maintenance departments and that's where I bought the German books from a local ( large city ) electronic spares for the industry wholesaler.
Your Ic max is 1 amp , 2SD1681S is higher than that , you don't go backwards in spec you go forwards as near to the original as you can .
Every semiconductor data book for selecting equivalents gives a fixed current that you work to , in any case the range of Hfe is shown to vary within a range of currents its just not published in public equivalent books .
For the 2SD1681 in UK types like the BD range its BD135 not BD140 both in the Mullard book and the German ECA highly respected book used by electronic / TV etc maintenance departments and that's where I bought the German books from a local ( large city ) electronic spares for the industry wholesaler.
Because, shock horror, the graphs don’t need to be exact if you know what you are doing, but stating
“I had to look for the same pin out plus the same bias ( that's a major point )”
and
“2SC3902 is showing the same Hfe bias of 100ma but its Hfe range can go up to 400 , the 2SD1681S can go up to 280.”
is misleading, like you are trying to win an argument based on one single piece of misconstrued information without paying attention to the full picture. Seems to be so much of this going on on this forum – not fair to mislead people.
Over the past few months I have dug through many Yamaha amplifier schematics and built a clone of the 80’s era HCA amps – which works very well – the thread is on here with pics/info/schematics. My view (as a design engineer) you may find a 1A part is suitable, even if the hFE drops a little. If the amp relies solely on hFE then it is a bad design, and none of the Yamaha amps I have looked at are bad designs, most are very good, and use high current parts (using 100mA or less) for the power handling.
The higher grade BD140/139 -16 parts have a hFE spec of 100-250. They are cheap, available, you can always buy a bag and measure some for higher hFE – which I would do anyway to match them.
“I had to look for the same pin out plus the same bias ( that's a major point )”
and
“2SC3902 is showing the same Hfe bias of 100ma but its Hfe range can go up to 400 , the 2SD1681S can go up to 280.”
is misleading, like you are trying to win an argument based on one single piece of misconstrued information without paying attention to the full picture. Seems to be so much of this going on on this forum – not fair to mislead people.
Over the past few months I have dug through many Yamaha amplifier schematics and built a clone of the 80’s era HCA amps – which works very well – the thread is on here with pics/info/schematics. My view (as a design engineer) you may find a 1A part is suitable, even if the hFE drops a little. If the amp relies solely on hFE then it is a bad design, and none of the Yamaha amps I have looked at are bad designs, most are very good, and use high current parts (using 100mA or less) for the power handling.
The higher grade BD140/139 -16 parts have a hFE spec of 100-250. They are cheap, available, you can always buy a bag and measure some for higher hFE – which I would do anyway to match them.
In the repair business where I worked for a while we did not sit down with a load of graphs to decide what equivalent part would do , near/nearest was good enough .
What you are getting at is designing equipment where--yes that would apply but I have yet to either go into and electronic workshop in the past or work in one where graphs were looked at .
Thats why wholesalers sold those equivalent books which were used by at least 100,s I know of personally .
Just because in today's easy access to download 1000,s of virtual apps relating to electronic design it gives the ability to criticize it makes me wonder how millions of repair shops were able to repair customers equipment ---but they did --amazing eh ?
What you are getting at is designing equipment where--yes that would apply but I have yet to either go into and electronic workshop in the past or work in one where graphs were looked at .
Thats why wholesalers sold those equivalent books which were used by at least 100,s I know of personally .
Just because in today's easy access to download 1000,s of virtual apps relating to electronic design it gives the ability to criticize it makes me wonder how millions of repair shops were able to repair customers equipment ---but they did --amazing eh ?
No, not amazing at all, it used to work very well.
But try searching for the 2SC3902 and find stock. Mouser shows the 2SC3902S and 2SA1507T parts as obsolete.
Since the component shortage issues several years back old parts are disappearing quickly, even ones that should have still been active based on manufacturer supplied info (virtually disappearing from the market overnight).
Using equivalent books just won't cut it.
Recently I have been using 2SB649A-C and 2SD669A from the supplier LCSC - they are manufactured by Foshan Blue Rocket Elec - whoever they are. But I couldn't find anything else that would do the job I wanted.
However genreally the hFE is lower than the 2SD1681S/2SB1141S, and you have to import from China. The BD140/BD139 would seem easier to get.
Only other "similar" parts are the KSC2960 and KSA1220, but I can't find stock, and I don't trust KSC fairchild parts having had issues with stability and noise, even where the design specs look similar or even identical to older parts, and so wouldn't recommend them to others if there is another option.
But try searching for the 2SC3902 and find stock. Mouser shows the 2SC3902S and 2SA1507T parts as obsolete.
Since the component shortage issues several years back old parts are disappearing quickly, even ones that should have still been active based on manufacturer supplied info (virtually disappearing from the market overnight).
Using equivalent books just won't cut it.
Recently I have been using 2SB649A-C and 2SD669A from the supplier LCSC - they are manufactured by Foshan Blue Rocket Elec - whoever they are. But I couldn't find anything else that would do the job I wanted.
However genreally the hFE is lower than the 2SD1681S/2SB1141S, and you have to import from China. The BD140/BD139 would seem easier to get.
Only other "similar" parts are the KSC2960 and KSA1220, but I can't find stock, and I don't trust KSC fairchild parts having had issues with stability and noise, even where the design specs look similar or even identical to older parts, and so wouldn't recommend them to others if there is another option.
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If that is the case I am obviously out of touch and will check up on the web for whats available .
Like you I don't trust many sellers as I spent years helping UK citizens who had been ripped off or sold substandard equipment .
China has 1000,s of electronic part suppliers but I got access to their government website and as far as equipment is concerned their laws state once sold to exporters its their responsibility not the manufacture if a fault occurs and they wont take back faulty goods .
The BD range will now be sold by companies I also do not trust,-- modern suppliers for quality long gone are Mullard and other manufacturers who sold by reputation.
I will keep in mind what you said.
Like you I don't trust many sellers as I spent years helping UK citizens who had been ripped off or sold substandard equipment .
China has 1000,s of electronic part suppliers but I got access to their government website and as far as equipment is concerned their laws state once sold to exporters its their responsibility not the manufacture if a fault occurs and they wont take back faulty goods .
The BD range will now be sold by companies I also do not trust,-- modern suppliers for quality long gone are Mullard and other manufacturers who sold by reputation.
I will keep in mind what you said.