Marantz Output Transistors

[Glenz75]

Hi Guys,

I'm servicing a Marantz 1150 amp which has blown output transistors, this model has some oddball type of TO3 package with the numbers S40443 and S40442 one being PNP and the other being NPN.

I can't find any reference to these in my databooks etc, and it seems to me these were made especially for Marantz.... A bit like the AU919 outputs...

If anyone can give me some info on these or some modern equivalents, that would be much appreciated!

Cheers!
Glen

 

[Fred Longworth]

In general, the output pairs I prefer are:

2SD555/2SB600 -- maker NEC
MJ15024/MJ15023 -- maker Motorola

Best,

Fred Longworth
http://www.repairaudio.com

 

[phidauex]

Are you saying the MJ15024s are equivalent to the Marantz outputs? They are definately good transistors, and are better spec'd than many older transistors. But because of this, I've heard they can cause oscillation in unstable amps, when I replaced my XPL909 outputs devices in my Phase Linear with MJ15024s, I had to add slowdown capacitors on the line drivers to prevent oscillation. Maybe the Marantz is designed differently though.

They are nice transistors though, and are a lot more available than the 2SD555s. They are very closely matched, and spec'd very nicely. A bit spendy to replace 24 of them on the Phase Linear though...

peace,
sam

 

[jblmar]

I agree with Fred. I replaced original Marantz output transistors with Motorola MJ series. Don't forget that the replacement tr's have 30 years on the originals. I checked them on my oscilloscope with a component tester connected. Much better isolation compared to the originals.

Ron

 

[EchoWars]

In general, the output pairs I prefer are:

2SD555/2SB600 -- maker NEC
MJ15024/MJ15023 -- maker Motorola

If you have a source for those NEC's, please share...

Those are the most counterfeited transistors on earth, and I'd love to get my hands on some originals...

 

[phidauex]

Yeah, I was just going to note, the MJ15024 is also very commonly counterfeited. Get a good source. If the price seems too good to be true, its probably a fake. There are a few folks here who may have some, I got a bunch from d3imlay, and they are definately good ones.

The 2SD555's are gone. Someone may have a few in a box somewhere, but they are gone, give up. I've got a full set of 10 of them on one of my Phase Linear's channels, if you want them, I'll trade for MJ15024 (real ones).

peace,
sam

 

[jblmar]

I buy transistors from my neighbor who owns a supply store. They sell to the trade and therefore make certain that all their semiconductors are not fakes. Very reliable.

Ron