DIY Sony VFET pt 1

[chromenuts]

Edit: Thank you ZM. This is the second time you've saved my tail.

This is in ZM’s DIYAudio contract…saving of tails is a necessity that is directly related to ZM’s relentless presentation of amplifier projects one after another which leaves all of us chasing our tails 🙃😂🤪

 

[Zen Mod]

it was Dennis, not ZM

anyhow, just look at schm, see which cap end is looking at speaker and orientate same way on pcb - to look at speaker pad

 

[ranshdow]

Well, happy to report the patients are out of surgery and look to have recovered well. In the process I discovered that a hot air pencil is the perfect tool for heating and removing multi-legged fuses & friends. It took only 15-20sec of heating on the back side of the PCB before the little Toshibas popped right out. It also worked well for something else I'd been ignoring, flipping an ALPS pot I'd mis-installed, so a happy lesson learned.

 

[Dennis Hui]

ranshdow, happy your Toshiba surgery went well.

I believe those jfets have symmetric drain/source pins (certainly the case when I curve traced samples at working voltages) so even if you hadn't catch that, you would have been fine.

 

[ranshdow]

Dennis, were you referring to the Toshiba K370/J108 pairs? These are what came in my kit. I believe these have the same internals as the larger packaged 2SK170/2SJ74 but I'm not certain. Would love knowing if the ones I have are Drain-Source symmetrical or not, I couldn't tell from the online partial spec sheet I found.

 

[Dennis Hui]

I was thinking of 2sk170/2sj74. But I have also curve traced 2sj108 samples and found them symmetric wrt drain and source.

I have not curve traced 2sk370 however.

 

[Zen Mod]

Pa confirmed plenty of times that they're identical to 170/74, just smaller case thus smaller dissipation figure

 

[6L6]

^^ Our esteemed Zen mod beat me to the answer.

 

[Dennis Hui]

From what I can tell, the datasheets differ only in the package/dissipation.

 

[Nelson Pass]

That is the case. I don't know why, but looks like someone wanted that package.

Anyways they were available at a slight discount through distribution years ago, direct from Toshiba.

And yes, they ,like quite a few Jfets are symmetrical, Drain for Source.

 

[Zen Mod]

conclusion - Toshiba JFets are having small Gyroscope inside

whichever way you turn them, they orientate

 

[Mooly]

The late great Bob Pease once told me that its easy to tell which is the drain and which is the source. He said

'You talk to it, you say to the pins, you are the source, and you are the drain'

It works every time.

 

[Marcopolo]

Hello

I would like if possible to have one or two Sony 2SK82 Vfet in order to reassemble my second CSX1.

If necessary, I can give you in exchange two 2SJ28 KF-33, KE-33 that I have left in my stock.

Ready to pay any price to find my second CSX1.

Best Regards,

Marcopolo

 

[ranshdow]

One of the last of the P-channel DIY Sony VFETs is built up now & singing. Done just in time for Christmas too. How cool is that?

(Eternally grateful not only to Papa for the lottery gift of the OS, FE and PSFILT kits at BAF2022, but to Gianluca for re-opening the chassis production, to 6L6 for the build guide, and to ZM for his modifications- note this one has M4 studs holding the T-bars to the heat sinks.)

 

[6L6]

Absolutely fantastic!! Well done, and what a great Christmas treat!

 

[Lewisknox]

Beautiful job. Merry Christmas

 

[Zen Mod]

 

[planet10]

BK10M?

dave

 

[ranshdow]

Yep. They're the garage test speakers. They're still shouty but also have that distinctive resonant horn effect in the midbass.

 

[planet10]

There are things you candy to the driver to sooth them out somewhat.

dave