The ultimate DIY? A Stax SRM-T2!

[Whitigir]

@swampsong I bid you lucks on building the T2.  Not sure if those sands are authentic, but the T2 is as mind blowing as it is, and fake/bad sands, will just make somebody want to shoot their brain out by trouble shooting....I did buy my board off the guy, but turned out that @GeorgeP confirmed to me about the different variations of the boards, and what I could use.  I still can’t thanks George enough, as I almost travel down the path that you did....

[swampsong]

Yes I'm a bit worried about the sand as well, he said he tested them, but considering the source everything is suspect now.. I purchased the DY294 tester, was going to run through all of them before even attempting to solder... would that be a good way to be sure? I remember reading there was another way to test them with a much more expensive device, I'll be rereading those posts as well. Of course i was also going to visual inspect each of them, compare them to the pics I've seen on this thread and in this forum to make sure they are real...

Also, it seems my board is the smaller one with an error? GeorgeP mentioned it can be fixed, does anyone have a link to that or more info? If not i guess i should declare them a loss and see about getting in on GeorgeP next board run... i'm thinking more and more i'm going to do that no matter what... Yes its expensive but i'm stubborn and i won't stop until i have one working.. cost is always a concern but this project is about a lot more than just money... if that makes sense.... and why else do i work 12 hour days, if not to have expensive hobbies But before writing off all these parts, i need to be sure....

 

Edited August 22, 2018 by swampsong

[GeorgeP]

The Board error is an easy fix - a missing trace if I recall. There are some posts on it in this thread. I seem to recall G600 had this issue.

Why not post some pics of the sand (2sk216, 2sj79, 2sc3675 and 2sa1486) - sometimes it is easy to tell from a visual.

[swampsong]

I will i'll get some pics up later tonight, thank you all

[swampsong]

I shrunk the images so they would fit the limit here:

2sa1486

 

2sc3381

 

2sc375, looks like i have three different kinds?

 

2sj79

 

2sk216

2sk46

 

So what do you all think? did i get screwed, are the pics bad, i can look up how to link to the full res ones tomorrow if so... thanks for any help

[JoaMat]

I suggest you use the DY294 tester. It will give you a pretty good hint if the device is OK.

[Whitigir]

I think this is the first time I see bend legs SA1486.  I did collect the 3675 with bend legs from Japan source to keep on the preserve.  Very interesting 

[JoaMat]

The DY294 is of course only to check the breakdown voltage of a device. Additional to the DY294 I use MK-168 transistor tester (ebay from China) which seems to do quite well.

If difficulties sourcing original parts some of them could very well be replaced with now in production pieces.

[swampsong]

Thank you JoaMat i looked up that MK-168 going to order one its not very expensive...

Yes i wondered about sourcing some new parts, like for instance, the six 680uF/450v i need for the power supply, the part number on the original BOM is no longer available, could i substitute with these ones 594-MAL225957681E3: https://www.mouser.com/ProductDetail/594-MAL225957681E3

Also for the op27, i'm not sure which ones are the right ones to get... My BOM says allied electronics and has a part number of 630-0741 but i can't seem to find that? Is there a newer part number i can use on mouse or allied?

 

 

[brazilnut79]

On 8/21/2018 at 5:03 AM, kevin gilmore said:

I think I sold the complete chassis with angle brackets and board set for $1295, but I was not making any money. (No sand)

one more for posterity. Really like this one, definitely takes talent to do this.

I shall be sure to be (much) more careful

On 8/21/2018 at 5:03 AM, kevin gilmore said:

I think I sold the complete chassis with angle brackets and board set for $1295, but I was not making any money. (no sand)

one more for posterity. Really like this one, definitely takes talent to do this.

I shall be sure to be (much) more careful.

[Whitigir]

2 hours ago, swampsong said:

Thank you JoaMat i looked up that MK-168 going to order one its not very expensive...

Yes i wondered about sourcing some new parts, like for instance, the six 680uF/450v i need for the power supply, the part number on the original BOM is no longer available, could i substitute with these ones 594-MAL225957681E3: https://www.mouser.com/ProductDetail/594-MAL225957681E3

Also for the op27, i'm not sure which ones are the right ones to get... My BOM says allied electronics and has a part number of 630-0741 but i can't seem to find that? Is there a newer part number i can use on mouse or allied?

 

 

Capacitors, this is what I am using and it is available here

https://www.mouser.com/ProductDetail/647-LGM2W681MELC40

Op27, this is what I used in mine, and you can find it here

https://www.mouser.com/ProductDetail/584-OP27EZ

Edited August 22, 2018 by Whitigir

[swampsong]

Thank you Whitigir, much appreciated, there is one other part i was having track down:

I need 4 Bridge rectifier, part number 512-kbu4m but it appears to be obsolete as well, would part number 512-GBU4M be okay?

The specs are pretty similar... But i didn't want to assume...

After that i just need to find the screws and wait for a few backorder items on mouser and i think that is it...

 

 

[Whitigir]

32 minutes ago, swampsong said:

Thank you Whitigir, much appreciated, there is one other part i was having track down:

I need 4 Bridge rectifier, part number 512-kbu4m but it appears to be obsolete as well, would part number 512-GBU4M be okay?

The specs are pretty similar... But i didn't want to assume...

After that i just need to find the screws and wait for a few backorder items on mouser and i think that is it...

 

 

Yes, that is fine, and is what I used in mine

[swampsong]

Okay ordered thank you again

[kevin gilmore]

updated shrunk board files with missing trace fixed and rounded corners

staxt2powershrunk.ZIP

t2shrunk.ZIP

Edited August 24, 2018 by kevin gilmore

[JoaMat]

In April I reduced the 500 V and 560 V sections by a 100 volts. I’m satisfied with the results so from now on 400 V will be my first choice. Today I’ve reduced the positive 250 V to 220 V. It shouldn’t effect the quality of sound at all.

[swampsong]

FYI: The guy on headfi (kytuphicanh) that bought my chassis and board set from just sent me this: 

I’ve just finalized a 2018 version of the T2 boards with Kevin Gilmore. Some small errors fixed, silkscreen edited here and there, a bit easier to work on (slimmer, less copper thickness), rounded corners. Going to order a small batch soon, if you are interested in for back up, let me know, I will squeeze in for you. They come in red this time though.

I was already going to order a new set with GeorgeP, are these the same ones you will be doing? And i'm assuming he is talking about the board layouts Kevin posted a few posts above?

Anyways hopefully Sunday i can start getting all of my parts layed out and begin my plan of attack.  Thanks to everyone for all of their help.

-James

[kevin gilmore]

The latest gerber files posted above are the same as I sent to kytuphicanh

missing trace fixed, rounded corners and gerber v2.

It would take a whole bunch of time to netlist the board which would allow filleting. Current board works, so I will leave it alone.

[spritzer]

Netlisting one of these is an epic pain. 

[JoaMat]

2 hours ago, swampsong said:

Anyways hopefully Sunday i can start getting all of my parts layed out and begin my plan of attack.

 

I made those three tools when building my first T2. Bending resistors and diodes...a piece of cake.

[swampsong]

I like it, i'll make something similar, thank you JoaMatt

[kevin gilmore]

I did the same thing machining from aluminum, the 2 bends for all the heatsink mounted transistors. impossible otherwise.

here is a version of the shrunk amplifier board that has been netlisted and teardrop'd.  someone would have to check this carefully before making boards.

updated file, I think I got them all.

 

 

t2shrunknet - CADCAM.ZIP

staxt2powershrunknet - CADCAM.ZIP

Edited August 25, 2018 by kevin gilmore

[bui501]

Kevin, I have the original t2hvandlvpsukgsshv2 board you posted a few years back... do I just need one of those boards for the T2 or 2 of them? I noticed the new power supply board you posted yesterday is significantly different from the t2hvandlvpsukgsshv2 combination power supply.

[JoaMat]

t2hvandlvpsukgsshv2 is one of two power supply boards for T2. It has +/-500V, BIAS (580V), +/-12V and Stax version of delay flashing LED during pre-heat and then steady. The second board is t2250kgsshv and has +250V, -560V and a 300V section to achieve -260V.

I build a PSU with this boards some years ago to meet my preferences.

[kevin gilmore]

the power board I posted is the original board designed to fit into the vertical fin chassis. my original design for the t2.

the other boards were done by joamat. sure looks like they will fit into that chassis.