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kevin gilmore
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Hello Guys

 

I have noticed some changes, on the silkscreen of the v0.41 (boards from the current group buy) compared to earlier versions. The BOM in this thread seems to have missed some changes.

 

1. on the amp board, there is a 1k and a 2k trimpot. current BOM says 2x 2k

2. On the PSU board the zeners are now 24V, BOM says 12V.

3. Can someone confirm which leds to use? I suppose its the same ones as in the KGSSHV (i.e. 859-LTL-307ELC) 1.7V, 2mA

4. Of course if you want to run at the recommended 350V instead of 400V you need to adjust the zenerstring to 2x100V and 1x150V

 

Happy building

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The balance pot should always be 2K but the offset needs to change with the voltage.  Last one I built used 1K pot and 1.37K resistors at 400V but 1.5K should be fine at 350V.  This resistor has to be 1/2W and higher wattage doesn't hurt as it gets hot. 

 

24V is better so use that. 

 

Those are the correct LED's. 

 

Yup, we forgot to change the zener string values.  :palm:

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The pcbs look good thanks Kevin and Birgir.

 

Have attached some images which will help builders.

 

The zener voltages have been mentioned, notice on the PS the 0.1microF/1000v caps have a pin spacing of 15mm.

 

Make sure the 24v zeners by the big caps are in the correct way as you'll not be able to get at them when it's assembled.

 

On the amps the 0.1microF caps by the servo are very small 2.5mm lead pitch.

 

Other than that it looks a very straightforward build.

 

Have fun.

 

 

post-3955-0-36649700-1408014413_thumb.jp

post-3955-0-68423100-1408014433_thumb.jp

post-3955-0-74756600-1408014471_thumb.pn

post-3955-0-36564300-1408014480_thumb.pn

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Some dumb questions here:

 

What voltage rating should the 1uF and 0.1uF capacitors be?  (On the right side of the amp board.)  I didn't see them marked on the silkscreen.  

 

For the LSK389, do I want the A, B, C, or D?  (2nd page on http://www.linearsystems.com/assets/media/file/datasheets/LSK389.pdf )

 

Also, does anyone have part numbers for the amp and PSU heat sinks (both the large and small ones)?

Edited by chiguy
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The 1uf cap has to be 25V+ so anything with 15mm lead spacing will work.  I use 250V Panasonic caps which fit perfectly into the footprint.  Kevin posted the part number either here or in the KGSSHV thread.

 

The 100nf caps should be rated to handle the B+/B- plus a bit of headroom.  We've normally used 1000V caps here but 630V also works. 

 

The rating of the input fets doesn't matter, just as long as they are the same grade on both channels.  I normally use LSK389 B series  and BL grade 2SK170's.  Now that the BL units are almost finished I'm moving to my GR stock. 

 

Here are the heatsinks, big one for the CCS and pass transistors:

 

532-530002B02500G

 

and the small one for the 10m90 CCS in the PSU:

 

532-581002B02500G

 

Remember to order the proper insulation pads, shoulder washers and you also need 6/32" screws (either nylon or peek) for the small sinks. 

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Waiting on some 1N914 diodes (my stash from 2004 finally ran out) but the KGDT if just about ready for testing:

 

1vkzhdbh.jpg

 

Shown next to the new KGST boards, a smaller version of the group buy boards.  The difference is not great but I had to shave off a few millimeters to get them into a chassis I bought. 

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Looks good :)

 

Shown next to the new KGST boards, a smaller version of the group buy boards.  The difference is not great but I had to shave off a few millimeters to get them into a chassis I bought. 

 

Stop doing this to us - you know we always want the latest and greatest :mikey2:

 

//UFN

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