The ultimate DIY? A Stax SRM-T2!

[livewire]

Thanks again chinsettawong. Got it!

[Kerry]

Thought you all might want to know that BDent has the 2SK216's back in stock.

[cobra_kai]

Thought you all might want to know that BDent has the 2SK216's back in stock.

They must not have had too many because they are all gone already.

[Kerry]

Wow... That was fast.

I asked to be notified via email from BDent. I got the email this morning and checked availability. They still had some available.

[ujamerstand]

posting pictures of the fake 2SA1486:

breakdown voltage: (real ones have Vbr at around 700V)

back side: (notice epoxy sloppily applied)

front side: (The dimples are rubbed out on some devices indicating the original print is scoffed off. In fact, the real device look completely different.)

all 70 of these things go in the garbage can. They were sourced from utsource.

[luvdunhill]

Those look like Toshiba devices.

[livewire]

MIne test at a Vbr of ~701 to 720V. Bought them at Bdent.

Where did you find the Vbr spec on these?

My NEC datasheet does not list it.

Sorry to hear you are sitting on so many trash parts....

[ujamerstand]

I'm sitting on so much trash parts it's trash parts kingdom around here.

You can find it in the datasheet under maximum voltage, which is rated at 600V.

[livewire]

I must be missing something, I see max voltage listed at 600V on the datasheet, but no reference to V(br).

Your results are believable though. Sorry to see it.

[kevin gilmore]

could be relabeled 2sa1413 which are 400 volt parts.

[justin]

this same problem exists with parts machined in China. pay for USA aluminum (like 5% of the part cost), get Chinese aluminum which cant anodize properly.

[spritzer]

I must be missing something, I see max voltage listed at 600V on the datasheet, but no reference to V(br).

Your results are believable though. Sorry to see it.

The Vbr should be a comfortable margin over the Vmax spec but there is no given limit for this and it varies from unit to unit.

[justin]

hmm..got my DY294 tester, i am guessing mine is defective?

- set V(BR) to 1000V PNP

- insert 2SA1486 that i know is good

- get a measurement around 70V

- tried a 2SA1968 that i believe is real and get around 150V

- tried a 2SA970 (definitely real) get about 25V

ok, how about switching it over to NPN and put in the complimentary 2SC2240

- hmm, 200V range is too low. switch it to 1000V range.

- 215V .....thats either really good as the datasheet says 120V, or the # is wrong too.

Edited September 17, 2011 by justin

[ujamerstand]

I just tested the stock of A970 and C2240 that I bought from bdent a year ago.

A970 on the PNP-V(BR)-1000V settings: 208V

C2240 on the NPN-V(BR)-1000V settings: 183V

[justin]

sounds like my PNP side is busted

[ujamerstand]

Yeah, 70V on the 2SA1486 is some wonky readings. That side is busted.

[justin]

wait a sec. i am now getting 745V, but i had to flip the part around. inserted into the tester with the leads reversed from what you show in your photo.

[ujamerstand]

which part? When I tested the real A1486, I inserted it into the tester with the back side of the transistor facing me. (The face that interfaces against the heatsink)

Edited September 17, 2011 by ujamerstand

[justin]

yes, when i do that i get the ~70V. when i flip it around so the labeled side of the A1486 faces me, i get the correct 700V. this is true of both batches of 2SA1486 that i have, ones from bdent (that have been used for BHSEs so far) and ones from dalbani that look slightly different.

Edited September 17, 2011 by justin

[Milosz]

These arrived from RichTech and look to be genuine- the logo looks like the Hitachi logo I've seen on other parts, and the date code looks sensible. Have to wait until my transistor characteristic checker arrives from China to see for sure if these are the real deal.

My transistor checker arrived. Measured the 2SK216's from RichTech and they have a breakdown voltage of 229 volts +/- 1 volt. So they SEEM OK.

[ujamerstand]

Folks, 2SC3675 is back in bdent. 150 left in stock.

[n3rdling]

Thanks!! I was worried I wouldn't be able to get a lot of this stuff. 2sk216 and 2sj79 also back in stock

The BOM says 2sk246GR but I was wondering if 2sk246 or 2sk246BL is a suitable substitute?

[blubliss]

yes

[Horio]

Thanks!! I was worried I wouldn't be able to get a lot of this stuff. 2sk216 and 2sj79 also back in stock

The BOM says 2sk246GR but I was wondering if 2sk246 or 2sk246BL is a suitable substitute?

N3rdling, I bought a (100) of these things from Zhou Fang of DIY Audio for a good price. I am planning to go through and test all of them, and do a rough match. Seeing that we only need (4) of them, I could probably send you a set. Just shoot me a PM if you are interested.

Edited September 23, 2011 by Horio

[Milosz]

How many DIY T2's have been built / are up and running? 8? 12? More?

There's a second wave being built now, about 15~18 units....

My PCB's just arrived. This amp board is large, for sure. You get an idea of the scale in this photo. I love it.

PS- that's the regulation "small part/small fastener" -pattern industrial carpet on the floor of my workshop that you see there. I've spent may lovely hours sharpening my cursing skills whilst kneeling on that floor looking for an SMD diode or a #2 washer.

Edited October 8, 2011 by Milosz