SAP15 Darlington Transistors

[NodeJunky]

My P's SAP15's have died in my A5 amp the N's seem ok, does anyone know a reliable source for these or is fleBay going to be filled with fakes?

 

[jan.didden]

There is an alternative type: Sanken STD03N and STD03P I believe. Functionally the same but without the build-in Re.

Edit: Blocked

Jan

 

[Nisbeth]

Obsolete but still stocked at Profusion? SAP15NY Darlington Transistor | Profusion

 

[Bigun]

I have used a different type of Sanken Darlington, maybe they can be used in your application?

TGM6 - modified Pioneer HT amplifier

2SD2390
2SB1560

 

[JMFahey]

Just thinking aloud: can´t you make a thumbnail sized miniboard and "build up" a functionally equivalent discrete replacement?

 

[davidsrsb]

No external diode is as well and rapidly coupled to die temperature as the built in one

 

[NodeJunky]

There is an alternative type: Sanken STD03N and STD03P I believe. Functionally the same but without the build-in Re.

Edit: Blocked

Jan

Thanks for the suggestion sorry for the silly question but what do you mean by Re?

Obsolete but still stocked at Profusion? SAP15NY Darlington Transistor | Profusion

Thanks bud but unfortunately they are the wrong channel I need PY's not NY's

I have used a different type of Sanken Darlington, maybe they can be used in your application?

TGM6 - modified Pioneer HT amplifier

2SD2390
2SB1560

Thanks bud I will have a look at your project!

Just thinking aloud: can´t you make a thumbnail sized miniboard and "build up" a functionally equivalent discrete replacement?

That could be a fun idea! I have the skills just not sure the brain to work it out XD

No external diode is as well and rapidly coupled to die temperature as the built in one

Sorry could you explain more?

 

[mjf]

........Re: emitter resistor (mostly 0,1.........1 ohms) is inside the case of the sap transistors (see data sheet), that is uncommon.
and the thermal tracking diodes are also inside the case - should give the fastest reaction if temperature changes........

 

[NodeJunky]

........Re: emitter resistor (mostly 0,1.........1 ohms) is inside the case of the sap transistors (see data sheet), that is uncommon.
and the thermal tracking diodes are also inside the case - should give the fastest reaction if temperature changes........

Ah I see thank you!

 

[jan.didden]

Yes. In the original transistors, the build-in Re used to break too easily on overload, way before transistor itself would break. So they came out with the STD series that is internally identical to the originals, including the clever sense diode arrangements, but without the Re.

So you can replace the originals with the STD but you would need to add the Re resistors externally between two of the pins. It will all be clear when you compare the internal circuitry from the data sheet.

Jan

 

[JMFahey]

There is an alternative type: Sanken STD03N and STD03P I believe. Functionally the same but without the build-in Re.

Edit: Blocked

Jan

That is the solution, even better than originals.

Adding external resistors is *relatively* easy, we need some closeup pictures to see what space you have available.
At least one from component side, one from copper/tracks side, you will need to cut one track and scratch soldermask (the typically green "paint" covering copper) to solder a couple wires to the added resistor.

As of:

No external diode is as well and rapidly coupled to die temperature as the built in one

Sure, nobody argues that.
That said, IF no internal diodes were available , external sensing would have to do.
A viable alternative used by most other amps.

 

[NodeJunky]

Yes. In the original transistors, the build-in Re used to break too easily on overload, way before transistor itself would break. So they came out with the STD series that is internally identical to the originals, including the clever sense diode arrangements, but without the Re.

So you can replace the originals with the STD but you would need to add the Re resistors externally between two of the pins. It will all be clear when you compare the internal circuitry from the data sheet.

Jan

I see that seems like a better than the original solution then thanks!

That is the solution, even better than originals.

Adding external resistors is *relatively* easy, we need some closeup pictures to see what space you have available.
At least one from component side, one from copper/tracks side, you will need to cut one track and scratch soldermask (the typically green "paint" covering copper) to solder a couple wires to the added resistor.

As of:
Sure, nobody argues that.
That said, IF no internal diodes were available , external sensing would have to do.
A viable alternative used by most other amps.

The re-work will be no issue I am an NPI Tech for a PSU company so everyday I'm putting components and laying tracks where they don't belong!

I will get some pics of the board up asap

Thanks everyone!

 

[NodeJunky]

Here is a couple pics of front and back of board, if you need closer shots let me know!

As you can see C242 blown aswell

 

[mayky]

Does anyone have such a 100% original transistor? Does it have a protective diode or not? According to the data sheet, it shouldn't be in it.

 

[RM]

I have several. PM if interested.

R

 

[mayky]

I have too, the question is has diode or not. Please meassure one, collector - emiter.

 

[RM]

Mine are 15-20 years old. That should answer your question.

Otherwise I can check in a few hours.

R

 

[mayky]

I bougth from Aliexpess, but mine are not new transistors, looks likes dissasembled.

 

[RM]

As I have worked on both Musical Fidelity and Arcam in Norway, I have both. New and used. With emitter resistor.

R

 

[Hans Polak]