Hello,
On my audio amplifier one channel doesn't work. Pair of power TO3 NEC
transistors were damaged (NEC 2SD188A and a NEC 2SB545A).
I can buy these transistors but model 2SD188 is without "A" and 2SB545
is with "A". I try to find some information or data sheet of those
transistors but without any results.
Can I use 2SD188 without "A" and 2SB545 with "A" on the left channel and
2SD188A and 2SB545A on the right channel? Is it OK?
Any help is greatly appreciated!
Best regards!
Zeljko

"François Yves Le Gal" wrote in message
...
On Mon, 29 Aug 2005 09:19:10 +0200, Zeljko wrote:

Can I use 2SD188 without "A" and 2SB545 with "A" on the left channel and
2SD188A and 2SB545A on the right channel?

Suffixed versions are usually high gain versions. I would suggest that you
measure the -A transistors, then try to find standard versions with
similar
characteristics.



It's likely that the replacements you found aren't NEC product, but made by
God-Knows-Who. And trust me on this - you want to be able to trust the parts
you use. Inferior replacements may not just cause a re-do, they may cause
much more damage than the amp originally had.

Quality TO-3 package transistors are a bit hard to find these days - I
recommend using replacements from Onsemi, the former Motorola semiconductor
company.
Hard to beat MJ15024 and MJ15025's. Over-rated for your application, but
that's not a problem.

Mark Z.

Dana Tue, 30 Aug 2005 15:18:36 +0200 na news grupi rec.audio.tech=20
osoba pod imenom Fran=E7ois Yves Le Gal je napisala...
=20
Hmmm. The MJ15024 / -5 are quite different. For instance their Hfe is
spec'ed at 15 / 60 while the NEC are spec'ed at 30 /120.
=20
=20
=20

Do you Fran=E7ois Yves Le Gal maybe knows what is mean letter "A" of NEC=20
transistors, or can you send me datasheet of those NEC transistors. My=20
e-mail is new.lineATmail.inet.hr.
Regards!
Zeljko

Dana Tue, 30 Aug 2005 12:17:19 GMT na news grupi rec.audio.tech
osoba pod imenom Mark D. Zacharias je napisala...

Hard to beat MJ15024 and MJ15025's. Over-rated for your application, but
that's not a problem.


Now I am using Motorola Onsemi TO3 transistors MJ15003 and MJ15004, but
in original there was NEC 2SD188A and 2SB545A. I wish to use original
transistors because now I don't know is sound different than when I use
original transistors.

Regards!

Zeljko

"François Yves Le Gal" wrote in message
...
On Tue, 30 Aug 2005 12:17:19 GMT, "Mark D. Zacharias"
wrote:

It's likely that the replacements you found aren't NEC product, but made
by
God-Knows-Who.

You can still find the original NEC transistors.

And trust me on this - you want to be able to trust the parts
you use. Inferior replacements may not just cause a re-do, they may cause
much more damage than the amp originally had.

Agreed. There are many regadged inferior parts in circulation, not to
forget
numerous Chinese fakes.

Quality TO-3 package transistors are a bit hard to find these days - I
recommend using replacements from Onsemi, the former Motorola
semiconductor
company.

If similar devices are available... Or if you're ready to modify the amp.

Hard to beat MJ15024 and MJ15025's. Over-rated for your application, but
that's not a problem.

Hmmm. The MJ15024 / -5 are quite different. For instance their Hfe is
spec'ed at 15 / 60 while the NEC are spec'ed at 30 /120.



Sounds as if you're more knowledgeable than I regarding technical specs of
transistors - but isn't the hFe group (such as O,P,Y) marked on the case of
the device?

In practice I've never had a problem with this, though I have heard horror
stories, like using NTE outputs on a McIntosh MC-2300 for example -
something I would never do anyway.

BTW - B & D Enterprises is an Onsemi distributor.

I'm pretty sure the old NEC product is no longer available from NEC.
Toshiba, for example, hasn't nade the 2SD 424 and B554 for many years now,
even though they were quite popular in their day. I think the 2SD188 etc go
back to the '70's.

Mark Z.