View Single Post
  #5   Report Post  
Mark D. Zacharias
 
Posts: n/a
Default


"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.