TO-236 muting transistor

[PsychoM]

Hi guys,
I'm looking for a replacement for a 2SC3326A muting transistor.
I cannot find the original transistor and I have no idea about a decent replacement. It should be TO-236.

Here's the datasheet: http://www.semicon.toshiba.co.jp/info/docget.jsp?type=datasheet&lang=en&pid=2SC3326

Can anybody help me? Thank you very much 🙂

 

[fpitas]

Digi-Key has them:

Invalid Request

 

[davidsrsb]

Some very unusual characteristics. Reverse Hfe is not normally specified like this, very low saturation voltage and low capacitance

This must be a special design die, not just a selection of a common type

 

[fpitas]

Yes, it's an oddball transistor.

 

[richie00boy]

Post up the schematic, it's possible it can be substituted with another BJT or even MOSFET.

 

[PsychoM]

Thanks for all the help. It's difficult for me to order at digikey, but if there is no other way I will try it. Farnell or RS components is much easier for me, but they don't have it. I will post the schematic tomorrow. It's for a Roland XV-3080 synthesizer, the transistor is only used to mute the outputs during startup

It's

Verstuurd vanaf mijn LT22i met Tapatalk

 

[fpitas]

I know that Behringer also uses them for muting the DCX2496.

 

[PsychoM]

Here's the schematic. See page 19 , Q17-Q22.
https://www.dropbox.com/s/1nxcc5a4qfimjzn/roland_xv-3080.pdf
One of those is broken and creates a distorted sound through one of the outputs. Maybe I could just remove it.

 

[cliffforrest]

We used to worry about reverse Hfe when transistors were used "upside down" as choppers. Extremely low saturation voltage. I can see this being relevant to a muting switch.

But how to get Vebo to > 25V !!

 

[cliffforrest]

I could not leave it alone:

Some answers here:

link

 

[PsychoM]

Thanks.
I think it's strange they used such special devices for such a non critical operation.
Shouldn't it be possible to change them for low saturation voltage fets with a low on-resistance?

Verstuurd vanaf mijn LT22i met Tapatalk

 

[davidsrsb]

Because n-jfets need a negative gate voltage for normal unmuted operation. P-jfets are rare and expensive

 

[cliffforrest]

"I think it's strange they used such special devices for such a non critical operation"

Roland made a LOT of different products. They MAY have had thousands of these on inventory and designers were encouraged to use them. It happens!

 

[JensH]

You could also use an 2SD2704K from Rohm. It is available from Mouser as well as Digi-Key. The specifications look very similar. And it is intended for the same application.

 

[PsychoM]

Hi, thanks again for the answers.
They also have the original 2SC3326 at Mouser.
Great news! But shipping is 20 euros and that's just a lot for 1 or 2 transistors... 🙁

I don't have to pay shipping when I order at RS components or Farnell.
But they don't seem to have anything similar. The closest one I can find is a BSR19, but it has only 6V Vbe.

I have found the original 2SC3326 at RS components, but only in some countries - 'On backorder' in Australia; in Cyprus it says 'Temporarily out of stock in the UK'; the UK site states it's 'Currently not available for sale' and in Belgium it doesn't exist.
Strange, I'll send them an e-mail for an explanation.

 

[JMFahey]

Just for kicks, try any regular low power transistor there.
Say a BC something which you probably have.
It might even be a TO92 case one just tack solder legs in proper pads.
It wight work reasonably well and save you time and money.
Worst case, you pull it out and "wasted" what ....10 minutes?
Post results here either way.

EDIT: just read datasheet and, yes, it *is* one weird specialized transistor. Ouch!!
Anyway I'd *still* waste 10 minutes trying a standard transistor there. 🙂

 

[PsychoM]

You know what, I'm just going to unsolder it and see what happens.
It can't get worse than it is right now. And if it doesn't work, I'll order one very expensive transistor from Mouser 😉