About 2SC2071/2SA939 and 2SB649/2SD669

Discussion in 'Electronic Repair' started by KaLe, Aug 3, 2007.

  1. KaLe

    KaLe Guest

    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, Aug 3, 2007
    #1
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  2. KaLe

    David Farber Guest

    "KaLe" <> wrote in message
    news:-com.hr...
    > 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
    David Farber, Aug 3, 2007
    #2
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  3. KaLe

    KaLe Guest

    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!
    KaLe, Aug 4, 2007
    #3
  4. KaLe

    Guest

    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
    , Aug 4, 2007
    #4
  5. KaLe

    KaLe Guest

    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!
    KaLe, Aug 5, 2007
    #5
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