Please tell me, can I replace 2SC2071/2SA939 with 2SB649/2SD669?

Those 2SC2071/2SA939 are working as pre-driver transistors in one old
Sansui stereo receiver, and because I cant find it any more for buy (and
I have found non-working one 2SC2071 and two 2SA939), I wish to replace
all 2SC2071/2SA939 with this Hitachi 2SB649/2SD669. Can I do this, but
the most important to me is keeping original Sansui sound.

Comments are welcome!

Regards!

"KaLe" wrote in message
...
Please tell me, can I replace 2SC2071/2SA939 with 2SB649/2SD669?

Those 2SC2071/2SA939 are working as pre-driver transistors in one old
Sansui stereo receiver, and because I cant find it any more for buy (and
I have found non-working one 2SC2071 and two 2SA939), I wish to replace
all 2SC2071/2SA939 with this Hitachi 2SB649/2SD669. Can I do this, but
the most important to me is keeping original Sansui sound.

Comments are welcome!

Regards!

According to my 1986 Transistor manual these are the ratings.

2SC2071:

250V Vcbo
220V Vceo
50ma Ic
1 watt Pc
Beta 150

2SD669:

180V Vcbo
120V Vceo
1.5A Ic
20W* Pc
Beta 60-320

2SA939:

-250V Vcbo
-220V Vceo
-50ma Ic
1W Pc
Beta 150

2SB649:

-180V Vcbo
-120V Vceo
-1.5A Ic
1W Pc
Beta 60-320


* I'm not quite sure how the 2SB649 is only rated at 1 watt while the 2SD669
complement is rated at 20 watts. Also notice that these substitutes have a
lower breakdown voltage than the originals.

Good luck.
--
David Farber
David Farber's Service Center
L.A., CA

Dana Fri, 3 Aug 2007 14:33:57 -0700 na news grupi sci.electronics.repair
osoba pod imenom David Farber je napisala...

According to my 1986 Transistor manual these are the ratings.






* I'm not quite sure how the 2SB649 is only rated at 1 watt while the 2SD669
complement is rated at 20 watts. Also notice that these substitutes have a
lower breakdown voltage than the originals.

Good luck.


Thank you for that information David. About collector power dissipation
different between 2SB649 and the 2SD669; they are talking about two kind
of Pc, one is normal Pc and one is Pc with mark * and notice Tc = 25
degrees C, that Pc with * is 20 W, and Pc without * is 1 W.

I do not need that high breakdown voltage, 180 Volts is quite enough,
because they will work as predrivers in audio receiver Sansui G8000.
But I am wondering about that big difference between collector current,
2SC2071/2SA939 have only Ic 50mA and 2SB649/2SD669 have 1.5A, how big
difference?!? Is it really good value, did you checked?

Regards!

On 4 Aug, 08:36, KaLe wrote:
Dana Fri, 3 Aug 2007 14:33:57 -0700 na news grupi sci.electronics.repair
osoba pod imenom David Farber je napisala...

According to my 1986 Transistor manual these are the ratings.

* I'm not quite sure how the 2SB649 is only rated at 1 watt while the 2SD669
complement is rated at 20 watts. Also notice that these substitutes have a
lower breakdown voltage than the originals.

Good luck.

Thank you for that information David. About collector power dissipation
different between 2SB649 and the 2SD669; they are talking about two kind
of Pc, one is normal Pc and one is Pc with mark * and notice Tc = 25
degrees C, that Pc with * is 20 W, and Pc without * is 1 W.

Tamb=25C vs Tcase = 25C wont explain that much difference. You dont
use 20w trannies as drivers in a tr amp.

Also your betas are different, 60 may be not enough.


I do not need that high breakdown voltage, 180 Volts is quite enough,
because they will work as predrivers in audio receiver Sansui G8000.
But I am wondering about that big difference between collector current,
2SC2071/2SA939 have only Ic 50mA and 2SB649/2SD669 have 1.5A, how big
difference?!? Is it really good value, did you checked?

Regards!


I wouldnt choose a 20w tr as a driver. It may well work tho.


NT

Dana Sat, 04 Aug 2007 09:09:42 -0700 na news grupi
sci.electronics.repair
osoba pod imenom je napisala...

Tamb=25C vs Tcase = 25C wont explain that much difference. You dont
use 20w trannies as drivers in a tr amp.

But in datasheet you can read two different values for Pc (collector
power dissipation). First Pc data is really 1W and second Pc data has
notice "Value at Tc=25" and that second Pc has 20W.


Also your betas are different, 60 may be not enough.


No problem about that, beta is for my model with mark "C" from 100 -
200.



I wouldnt choose a 20w tr as a driver. It may well work tho.


I wil not use them as drivers, I will use them as pre-drivers instead
2SA818/2SC1628 or instead 2SA939/2SC2071.
Please take a look at http://tinyurl.com/2xgp3o and you will see that
G8000 has as drivers 2SA968/2SC2238.

Regards!