Marantz 2275 power supply question

[Steven Tate]

A hint from the John Kutzler bag of tricks: Watch the connections at the main filter caps while powering up with the lights off to see if any arcing occurs. This would indicate a poor connection. Better yet would be to have a scope probe on each power rail at the affected amp to see if they both come up similarly at power up.

I will check it in a dark room and if nothing there, I'll try that measurement. I'm new to that kind of thing, but I think I can figure it out. Thanks!

 

[mrki]

So... the question is, is that same transistor a good substitute for both the SD331 and the SD330??

You may substitute both of them with MJE but it's a overkill. TIP31A is a nearest preferred replacement for both of them. Factory replacements for 2SD331/330 are 2SB515/514.
Btw, 2SD331/330 (or 2SB515/514) are the same. 2SD330/2SB514 are the 331/515's succesors.

And would any of the experienced guys have an opinion whether I should replace them or not?

Why should you replace them, at all? If they are fault free that's complete unneccessary. It's better to disassemble and clean 331 than reapply a new thermal compound or a grease... whatever. 330 hasn't got a heatsink because it doesn't need it. But you can add to it a T220 heatsink, like this, anytime.

 

[Steven Tate]

You may substitute both of them with MJE but it's a overkill. TIP31A is a nearest preferred replacement for both of them. Factory replacements for 2SD331/330 are 2SB515/514.
Btw, 2SD331/330 (or 2SB515/514) are the same. 2SD330/2SB514 are the 331/515's succesors.

Why should you replace them, at all? If they are fault free that's complete unneccessary. It's better to disassemble and clean 331 than reapply a new thermal compound or a grease... whatever. 330 hasn't got a heatsink because it doesn't need it. But you can add to it a T220 heatsink, like this, anytime.

Great information. Thanks!

 

[catrafter]

I always replace them, the 2SD330,331 have a Vceo of 50V which leaves little headroom. The MJE15030 has a Vceo of 150V and four times the current capability. Overkill? Probably, but I still do it. It takes about the same amount of time to clean and apply new thermal compound to the old one as it does to install the new device and compound. The cost is less than a buck and a half.
My 2 cents.

Tom

 

[mrki]

...It takes about the same amount of time to clean and apply new thermal compound to the old one as it does to install the new device and compound. The cost is less than a buck and a half.

Mr. Catrafter, I agree with you but I have to admit that I was a bit hasty in my previous post so I have to correct myself and give some additional explanations (because english is not my native language I apologize in advance for all mistakes I'll make).

We all know that each transistor is described with lot of data which are called Product Specifications. Electrical characteristics are part of overall specificatons and consist of many parameters and conditions. The best known of these parameters are:

• Vcbo - collector-base breakdown voltage
• Vce0 - collector-emitter breakdown voltage
• Veb0 - emitter- base voltage
• Ic - collector continuos current
• Pc - collector power dissipation

Above parameters are not the only ones, there are more of them like saturation voltages, cutoff currents, capacitances, biases, safe working area, bandwidth... and DC current gain (Ic/Ib ratio, hfe).
Actual circuit gain depends on other components too, not only transistor. But if the original transistor has a high gain, we'll try to match it. Additionaly, current gain falls off at higher frequencies, so a high-gain transistor can deliver a wider frequency response than a low-gain transistor.

Let's take a look, for a moment, at the Marantz 2275 schematics, P800 board. Above the board's schematics states: H801 - 2SD330 (D.E); H804 - 2SD331 (C.D.E.F). What's the meaning of these letters?
They desribes DC current gain (hfe) as follows (min-max):

• C 40-80
• D 60-120
• E 100-200
• F 160-320

It's well known that these transistor are discontinued and hard (better says - unable) to find, even 2SB514/515, their substitutions, too. Then we do some web search and find a transistor cross-reference web page. Finally, we populate the web page form with above parameters, press Search and the result is about 800 - 1,000 transistors which are suggested as replacements! That's not true. Only one (if you are lucky enough) is a substitute, one or two are nearest preferred replacement and that's that. Again, if you are lucky enough.

What about MJE15030? If we take a look into characteristics, we'll see that it may barely replace 2SD331 (because of low hfe) while it cann't replace 2SD330 because of insufficient hfe.
In my previous post I wrote that TIP31A is nearest preferred replacement for both of them. That's partially correct. With hfe from min. 25 to max. 50 it may barely replace 2SD331, not 330.

Luckily, there is a manufacturer which has a compatible part. The manufacturer is NTE and the name of the part is NTE152. It's a power amplifier silicon complementary transistor which will perfectly substitute both of 330/331. With hfe from 40 - 200, Vce0=90 V; Ic=4 A, Pc=40 W... and other parameters, it's better then genuine ones.

Mr. Catrafter, that's why I'm thinking that MJE15030 is not enough good replacement for both 330/331.
The post is a bit large, but I hope that this will help. Regards...

 

[Hipocrates]

 

[catrafter]

Thank you for your well though out comments. Your grasp of English is very good!
While I agree with your assessment on paper, my recommendation was based on my actual experience.

Here are some room temperature (25°C) measurements of DC current gain of actual On-Semi MJE15030, Sanyo 2SD330 and Sanyo 2SD331 devices.
.....................................Ib 10uA.......................Ib 1mA......................Ib 10mA
MJE15030........................93..............................120...........................71
2SD330(D)......................80..............................112............................63
2SD331(C)......................90..............................119............................70

Tom

 

[Steven Tate]

Very informative posts by both of you. It's all a little addition to the body of knowledge for relative newcomers like me.

 

[rBuckner]

If we're talking about a power supply still, Hfe has nothing to do with it in considering a replacement, it's all dc voltage.

 

[Briant8]

Lord.....
Why do I feel like whenever I get my head above water doing this, someone throws me another brick!
Definitely informative. Definitely overwhelming.
Kudos to those who think in these lofty realms!

 

[catrafter]

The original poster referenced DC current gain in his post so I addressed DC current gain in my post.
DC current gain - sometimes called hFE (although he erroneously called it hfe), is not AC current gain - sometimes called hfe.

Tom

 

[mrki]

Mr. Tom, thanks for usefull informations. I didn't supose that 2SD... can be substituted with MJE... I'll give it a chance in the next project, especially as readily available in my area and inexpensive.

 

[catrafter]

Mr. Tom, thanks for usefull informations. I didn't supose that 2SD... can be substituted with MJE... I'll give it a chance in the next project, especially as readily available in my area and inexpensive.

You are welcome!

Tom

 

[Steven Tate]

Just thought I would complete this thread with a couple of pics of the final product. I replaced all electrolytic caps on all boards plus filter caps, a few transistors and diodes, and replaced all of the lights with LED's. All of the adjustments centered up properly, and measured output at clipping with 1 khz signal on an o-scope. Both channels were right at 27V which translates roughly to 91 wpc with THD not known. The unit sounds great, so it's time for a little listening and burning in to see how it settles out. This one was a challenge, but with all of the great help on AK, I think it's going to be a good one. Thanks!

 

[MBuras]

Looks nice!

 

[EchoWars]

Thank you for your well though out comments. Your grasp of English is very good!
While I agree with your assessment on paper, my recommendation was based on my actual experience.

Here are some room temperature (25°C) measurements of DC current gain of actual On-Semi MJE15030, Sanyo 2SD330 and Sanyo 2SD331 devices.
.....................................Ib 10uA.......................Ib 1mA......................Ib 10mA
MJE15030........................93..............................120...........................71
2SD330(D)......................80..............................112............................63
2SD331(C)......................90..............................119............................70

Tom

On-Semi likes to quote 'minimum hFE' in the data sheet, which is just about always terribly pessimistic. Even if it were not, in most cases it won't matter much.

So yeah, good examples Tom.

 

[Fenix479]

So..... it isn’t clear to me sorry guys.
What would be the best substitute for
2sb514 (Pnp)
2sd330 (npn)
???????????
Thanks