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

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!

Reply to
KaLe
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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
Reply to
David Farber

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

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!

Reply to
KaLe

2SD669

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

NT

Reply to
meow2222

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

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.

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

200.

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
formatting link
and you will see that G8000 has as drivers 2SA968/2SC2238.

Regards!

Reply to
KaLe

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