That all sounds really neat! I'd love to see some photos and schematics if you have any. :)
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That all sounds really neat! I'd love to see some photos and schematics if you have any. :)
Prototype.Quote:
Originally Posted by 6L6
just about to start a tidy up for the final version.
The two sub boards in the top right will be one board slightly smaller .
REgs on the left in the trf hole will be sitting horizontally with the regs vertical. I have to make a new base to hold them with enough aluminium on the vertical to mount the regs. I have to improve the input connection.
Parts are en route from farnel UK.
http://i824.photobucket.com/albums/z...m/XE2A4336.jpg
Main reg board on plate to fit into the transformer housing.[IMG]http://i824.photobucket.com/albums/z...m/FXT11670.jpg[/IMG]
Noise on Scope-- less than 1mv pkto pk [IMG]http://i824.photobucket.com/albums/z...m/FXT11668.jpg[/IMG]to Pk
noise spectrum to 3Mhz[IMG]http://i824.photobucket.com/albums/z...m/FXT11667.jpg[/IMG]
Is anyone interested in a DIY improvement to their Techie ??
Good on you Ian, impressive stuf you are doing :)
Are these with the motor running?Quote:
Originally Posted by Ianmac
No, both main regs on soak test loaded to 500ma and subs to 100ma.
Im trying to buy a damaged platter so I can machine it and weight load it to be a motor section only and scope the innards with the mini platter/motor running. Unfortunately Platters are being sold for silly money on Ebay.
Im away for a few days but when I get back ill try and get two wires out of my deck and give you some more figures. I will also be modifying a second deck to this spec when I get back.
My own earlier PSU was transformer rectifier box with unreg DC fed to my regulator fitted in the old transformer housing. Anyone with a similar set up need only build another reg and split feed the supply to Control and Motor.
The sonic improvement I am getting makes this mod well worth the effort.
Thanks for your pointer to the Cmos chip.
Why don't you pass the probes through the power cable holes? They should stay nicely under the platter with some duck tape.
OK 3 and a half years later, let's do some work on Jim's original design.
It's time to get rid of that semi-random 220nF snubber and replace it with a proper actually working snubber, measured for the actual stock SL1200 transformer.
To do that, I used the Quasimodo jig designed by Mark Johnson at diyaudio.
http://www.diyaudio.com/forums/power...-test-jig.html
Here is Mr Q banging the stock transformer like a salvation army drum :p
Attachment 18744
This one is with the snubbing circuit in place. Still not perfect, but looking good.
Attachment 18745
Here I have gone too far and overdamped the thing
Attachment 18746
And here it looks about right. No signs of ringing.
Attachment 18747
Zooming a bit to verify it. Again, no signs of ringing.
Attachment 18748
The juice/schematic/values on the next post because I cannot upload any more images on this one
The snubber schematic is this
Attachment 18749
Values are
Cx: 10nF
Cs: 150nF
Rs: 270R
Caps were red wimas, and R should be 0.5W non inductive.
This is for a primary wired for 230V.
For 110V the Rs should be a bit lower. I am too tired now to look for the wiring diagrams to rewire the transformer for 110V.
If someone can tell me how to rewire it, I will try to get some time tomorrow and get an accurate measurement for 110V too.
In the meantime, something like 250R should be a good starting value to help you evaluate this mod
Unfortunately the motor ICs are not yet here so I cannot test it myself and report any sound changes.
I promise I will report back as soon as I get the turntable up and running.
I believe Paul also discussed this subject in his posts on DC power supplies about 3 years ago.