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The ultimate DIY? A Stax SRM-T2!


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Finished...   Back plates before I mounted them...

I finally got the last plate machined.  I had to replace the spindle on my CNC and also made a mistake on the CAD so had to redo this plate, but it's looking great now.  

So here's a progress update on my T2 mini build. I started off with the a golden reference version of the T2 supply.  Had a couple of issues.  There was some 60Hz noise I was hearing (I'm guessin

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Actually it was more like 650 volts where they blew thru on the
Original t2 power supply. Pictures were posted. Unreg primary
On the anode of the current limiters. The same would be true
For the bias current source.

 

The Polyphenylene Sulfide ones are the only ones actually rated for the voltage

and they are an impossible fit for the 2sc3675.

 

This, but like I said, a very tight fit

http://www.futureelectronics.com/en/technologies/electromechanical/thermal-management/thermal-tapes/Pages/1303239-7721-3PPSG.aspx?IM=0

 

The cap head version of the peek screws are just about impossible to overtighten.

I have tried. Also a fair amount less capacitance to ground. For the 2sk216 and 2sj79

definitely a good idea.

Edited by kevin gilmore
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I agree with previous posts that they don't provide enough torque.

 

what are you using instead? a metal screw?  i havent personally had problems with a metal screw and a nylon shoulder washer, though i havent done anything with unregulated voltages as high as Kevin mentions.

 

though from outsourcing assembly on things like this i cant trust them to properly use a shoulder washer. then again i also cant trust them to properly torque the plastic screws..

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That's the wrong part number and those are not rated for 500v. I had one punch

Thru. There are versions that are rated for the voltage but they don't fit the

Required transistors for the t2.

 

Yes, that was wrong part number. I’m sorry - it was late and I mixed up the numbers. I use the insulating washer # 7721-3PPSG and I use a tool to press the washer in place. So far it works without problems for me. I have two working T2 and some other stuff.

 

But I can see the advantages using PEEK screws and it seems that the torque they provide is good enough.

Edited by JoaMat
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i think thats the same one i used to use.  the one that is thicker than the TO-220 so the washer extends into the aluminum oxide insulator. getting the washer to line up with the hole in the insulator was annoying. i just found that overall the PEEK screws were more idiot proof for contract assembly.  how many cracked washers would i get and never know about? 

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When I started to press them into place I avoided the cracking. But my concern now is what happens with the washers after a long time (years) and the heat. Will they become hard and therefore crack or fell apart? Time will tell.

I think I better get some PEEKs.

Justin, I'm in for 200 pcs.

Thank you.

With the PEEK screws the question is whether you need to use loktite. I think Inu did. If this is the case this presents a another issue other than the fact that you will get decreased device life from improper torque. I dont see it an obvious choice.

Justin may have a point given his situation. Others not sure.

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2sa1486 has exposed collector on the back side. and extra capacitance from metal screw on t2 definitely an issue

in all of the current sources where they are used. also capacitance is an very important issue for the 2sc3675 in the battery.

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