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i'm on a roll... the kgsshv

kevin gilmore

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I remember this had been how most people utilized the 1968s, but is it a given that that you cannot use a 500v PS with a 1968 build given the sanyo parts are good to 900v? I had thought Kevin or Birgir had posted on this previously but I am having trouble finding it now.


I got most of the info on that from the post below by Kevin. Is it the one you're talking about?



OK, the holdup for the last 5 weeks was trying to supply 2sa1968LS at a rational price. ($7.13 each is not rational)

I was told by the person that should know that they should be 70 cents each. So after contacting various

unsavory ic parts companies only to be told that my offer of $1.29 (mouser price on the ixtp compatible part)

was WAY too low, i just gave up and decided to modify the layout of the board to incorporate both current

sources. Literally 10 minutes after i uploaded the files below, i get an email with a quote from a british

distributor, and guess what... 70 cents each. (plus or minus due to exchange rate)

Since lots of things have been changed or moved around, lots of checking needs to be done.

also apparent discrepancies on the power supply schematic vs the amp board are due to the

differences in voltage. If you go with the 2sa1968ls which i think sounds ever so slightly sweeter,

the power supply rails have to be +/-450 volts. If you go with the ixtp01n100d, then you can

go with +/-500 volt rails.





The amp board is 8.25 x 6.25 inches with 240 holes. you need 2

The power supply board is 9 x 7.5 with 374 holes.

The single transformer is going to be 4.5 inches in diameter and about 2.5 inches high.

(if you go with the SumR)

If i do the board run and do 20 sets, because i'm in illinois and so is imagineering...

the price increases by 9.5% due to sales tax. Which would make a complete board set $71.46. plus shipping.

If someone else wants to do the board run that's ok too, gerber files will be posted once

people verify that there are no mistakes.

Digikey is the only one with the 2.5 inch version of the aavid heatsink, mouser only stocks the 2 inch version.

2.5 inch version highly recommended. BOM now needs serious work.

I'm not doing chassis on this one. (well except for my nelson pass style chassis which is for me only)

Put it in a hifi2000 box, or hammond box, or a wood box. But plenty of top and bottom holes.



@Kerry That really does look very compact! Really looking forward to seeing the completed project :)

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Yeah, high current needs meatier devices to blow off the heat. The Dynalo, however...


I'm just really surprised how easy it is to solder 0805 parts. I might say that it can be faster than through-hole. The electrolyte caps are a bit of a bitch to solder, but those are better in tth anyways.

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Hey guys, so a quick update.  I was looking over the boards again and I noticed that my 10k led resistor (R51) is a little charred.  You can clearly see marks on the resistor.  Was looking at the circuit but wasn't sure why the 10k would be charring up.  any ideas?  here are some pics.  http://imgur.com/2wNdVa2,vRrWyeM#0   


Looking at the schematic, i'm not sure why the resistor would burn up  as i'm getting a good 15v from the psu.  I also replaced the 2sc1815 for good measure but still smelling dat burn...  


So the resistor is indeed 10k and still measures well.  still experiencing same symptoms.  have ordered new parts to replace the section but still unsure as to what might be wrong.

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assuming Kerry's boards work, and i'm sure they will, this is going to be a great solution for the off board amp

especially as it has the servo on it. Not as flexible and 450v only. But you gotta give somewhere to get down

to this size. Probably can squeeze the whole thing into a srm727 size chassis. Very sweet.


all of these boards are getting harder and harder for many people to build.

goes with the territory I guess. perfect solder jobs are going to be required in the


Edited by kevin gilmore
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Thanks.  Very fun stuff.  If all goes well I will make the gerber files available.  I don't mind a few mods.


@StrawHat - The connector on the right is not .2 pitch.  I use them because they are rated at 600V.  The part no at mouser is: 571-1-770170-0.  You should be able to easily find the mating parts.  On the left side where the audio inputs are it is .2" pitch and I used a 5 pin gold plated connector and just pulled out the 2nd & 4th pins.  That part number is: 538-22-11-2052.


Kevin is very right about the soldering.  It is very easy to have issues given the high voltage and closely packed components.  I examined every SMD solder joint with a loop to make sure that they were good and there was no possibility of shorts.

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Only thing I'm concerned about with Kerry's boards are the STN9310 temp given what I'm seeing in the onboard amp.  Might need to add some more area for heatsinking but only actual tests will verify that. 


Terrific layouting! I wish all Gilmore boards got such modernized layouts with smd parts where possible.


Give me through hole parts anyday so I very much doubt this is going to happen.  :) 

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I'm just really surprised how easy it is to solder 0805 parts. I might say that it can be faster than through-hole. The electrolyte caps are a bit of a bitch to solder, but those are better in tth anyways.


Yeah, this SMT board is awesome.  0805 is easier and faster, IMO, as well.  It's also easier to probe, and you can get devices on both sides if needed or in some cases.  IIRC, Justin uses SMT on his amps.  There's a stigma with some DIYers about SMT.  I'm not sure why.

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Thanks.  I want to use the digital attenuators, but I have to see if I can fit another power supply for them (didn't want to tap into the existing 15V supply). 


I might be able to mount another transformer on top of the existing one, but also need to see if I can fit the 12V / 5V supply.  I think I can, but it will take some thinking. 


I can make a digital controller that could easily mount to the front with a digital display.  If I'm doing that I would add and IR remote control as well.


@Victor - Yes, the power supplies are split + one side - the other.  Had to do everything possible to get this down in size.

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