Wanted: Accuphase Transistors!!

[flemo]

Hi Everybody,

I recently had a mishap with my Accuphase E205 amp and as such I need to replace a couple of resistors still to be identified and 4 x transistors.

My main concern is obtaining replacement parts for a 25 year old amplifier.

The attached pic hopefully provides the info for the transistors which I'm chasing.

Any help greatly appreciated, cheers flemo.

[jaycee]

that looks like one output transistor, one driver, and two transistors from the VAS. I can bet there is more wrong with it than this.

The driver is a MOSFET, unusual...

Unfortunately pretty much all of these will be obsolete by now. You will be better finding more modern equivalents, but expect to have to adjust the circuit to suit.

[zeonrider]

Originally Posted by jaycee

The driver is a MOSFET, unusual...

Why not, that is Trade Mark of Accuphase co.



Regards zeoN_Rider

[anatech]

Hi Flemo,
The only thing that might be more difficult to find may be the 2SK2662. The TO-126 parts can still be found, and are not hard to substitute. The output (2SB863 and compliment) should be even easier to find a substitute for. If any of these are paired, you must find a sub for that as well if you can't get the original part. I don't have the schematic, so I can't be sure on that.

Hi Jaycee,

The driver is a MOSFET, unusual...

Not common, but Revox did something similar with the B-242 in case you wanted to have a look. I suspect this is an attempt to make the load on the Vas more constant with load.

There may be other examples of this design out there, but I can't think of any past Revox off-hand. Anyone else know of any?

-Chris

[jaycee]

Originally Posted by anatech

Hi Flemo,
The only thing that might be more difficult to find may be the 2SK2662. The TO-126 parts can still be found, and are not hard to substitute. The output (2SB863 and compliment) should be even easier to find a substitute for. If any of these are paired, you must find a sub for that as well if you can't get the original part. I don't have the schematic, so I can't be sure on that.

My thoughts were to recommend teh Fairchild devices KSA1220/KSC2690 for the TO-126 devices, and FJA4213/FJA4313 for the outputs. However these are all faster and may cause trouble. Onsemi's NJW21193/4 might be better in this regard.

Have just noticed Onsemi are taking over Sanyo Semiconductor! Let's hope this means some of Sanyo's excellent devices become part of Onsemi's stable and thus more readily available.

Originally Posted by anatech

Hi Flemo,
Hi Jaycee,

Not common, but Revox did something similar with the B-242 in case you wanted to have a look. I suspect this is an attempt to make the load on the Vas more constant with load.

There may be other examples of this design out there, but I can't think of any past Revox off-hand. Anyone else know of any?

-Chris

I believe Michael Chua tried this in his Ampslab Bi70Mk2 amp. I seem to recall an old Marantz design like this too in my archives, would have to check.

[mt490]

A large amount of Sanyo's catalogue is quite readily available through RS components. But they've been discontinuing quite a bit of their stuff.

As for the outputs, based on the minimal information around I would have chosen 2SB817P/2SD1047P, but you're not in luck because these were just discontinued a few months ago by Sanyo.

The FJA devices mentioned above are probably appropriate, as well as the 2STA1962/2STC5242. If you want slow, 2SA2031/2SC5669

[flemo]

Originally Posted by anatech

Hi Flemo,
The only thing that might be more difficult to find may be the 2SK2662. The TO-126 parts can still be found, and are not hard to substitute. The output (2SB863 and compliment) should be even easier to find a substitute for. If any of these are paired, you must find a sub for that as well if you can't get the original part. I don't have the schematic, so I can't be sure on that.

-Chris

Hi Guys,

Thanks for the input. I should have mentioned that somebody else is working on the amp for me and after their examination concluded 4 x transistors and 2 x resistors were unserviceable.

I don't have the technical ability to perform such work or understand some of what you're saying, so please bear with me and dumb it right down!

Chris, the TO-126 parts you mentioned which ones are they in the pic's and where do you think I may be able to obtain them, or what could I substitute them with?

Thanks again for your help and hopefully I'll be able to get this wonderful amp singing again.

Cheers, flemo.

[anatech]

Hi flemo,
2SA1360 and 2SC3419 in the picture, but they are not compliments anyhow. Off the top of my head, a 2SC3423 should be the proper pairing for a 2SA1360. Is it possible he hasn't pulled the complimentary device from the unit? The 2SC3419 may be a bias transistor. Anyone have a schematic for this one they can email to me?

Now, I just have to ask. This fellow who is working on this for you, not much experience? Is this person at least specializing in audio, or is most of their work along a different direction? I'm starting to get a familiar feeling about this. There are other factors involved here beyond a replacement of parts thing. Some expertise is required for even mounting the new parts. Notice I didn't say "to screw the new parts down".

Hi jaycee,

Onsemi's NJW21193/4 might be better in this regard.

Yes, I would think so. I think there is still a variant of the MJW0281A and MJW0302A somewhere. Of course, if Digikey or Newark still have these, they would be perfect! A definite upgrade in quality to the original parts.

Have just noticed Onsemi are taking over Sanyo Semiconductor! Let's hope this means some of Sanyo's excellent devices become part of Onsemi's stable and thus more readily available.

Now that is interesting! Where did you hear about this?

Having Sanyo parts may answer my lament that we don't have great signal and low power devices. The newer On Semi outputs are absolutely top quality! Still, I'd rather see the Toshiba signal devices in On Semi's stable. What will probably happen is that On Semi will take the better Sanyo parts and integrate them into the product line while changing the part numbers a bit. This would solve the counterfeiting issues we all face.

-Chris

[jaycee]

Originally Posted by anatech

Now that is interesting! Where did you hear about this?

Having Sanyo parts may answer my lament that we don't have great signal and low power devices. The newer On Semi outputs are absolutely top quality! Still, I'd rather see the Toshiba signal devices in On Semi's stable. What will probably happen is that On Semi will take the better Sanyo parts and integrate them into the product line while changing the part numbers a bit. This would solve the counterfeiting issues we all face.

-Chris

The announcement is on the front page of onsemi.com
My main beef with Onsemi is no good TO-126 sized devices other than BD139/140, MJE340/350, MJE243/253 - all of which are a bit long in the tooth

[anatech]

Hi jaycee,
Same beef I have, but they are no worse than any other US manufacturer of semiconductors. I'd like to see some linear small signal BJTs and especially J-FETs as well. Everything they have is long in the tooth - and that's an understatement!

You know what would be truly wonderful for transistors? Pre-grading like the Japanese do.

-Chris