SL-1200 DC Power Supply DIY

[6L6]

I suggest using the stock transformer. If you really don't want to, send it to me, I would love to have a spare, they are very nice, and with the mount and shield would be very useful for other projects. And yours will have the dual primaries... Mine is single 120V

The KAB supply is a SMPS and so in a matter of speaking, pre-regulated. (The KAB is quite nice by all accounts.) I'm not sure if having a 317 based pre-regulator would be all that beneficial in the outboard supply. I would try a shunt regulator or a simple capacitance multiplier in the outboard, (or just more capacitance or RC stages) and then some kind of modern regulator (317 or something more fancy) in the TT chassis.

That said, your ideas seem quite sound, and are worth a go.

IF you can wait a bit (I'm out all next week for Captain recurrent training) ((I sit in the pointy end of jets for a living)) I am working on an easy LM317 based reg for inside the chassis. (The KAB DC-1200 is a LM317 design) After that I will try another configuration for the internal reg. (A "Tracking pre-regulator")

I will make a layout, plan and BOM for the simple configuration to be assembled on a small piece of stripboard. I actually knocked it together point-to-point, but a board would make things much easier.

Stay tuned!

[Qwin]

I'm in no hurry Jim so I will wait and see what you develop for the regulation.

I have two decks and only one transformer, so I have to buy either a second hand Techie unit off fleabay, or a 22V r-core, which is a similar price due to the genuine Techie parts carrying a premium price. (used item £25/35 +P&P over here)

I will now go and research some of the things you mention to try and appreciate how they effect things.

As allways your input has been appreciated.

[Frankyc2003]

As mentioned in various threads here, in the context of the Sl12xx regulation should happen as close as possible to the load. Meaning your LM317 or LT317 should stay within the body of the TT close to the motor and various chips. (let me know if I am talking garbage, as I am in no way an expert in the field)

A wee while ago, there was a debate about the TimeStep external power supply having a LM317 inside and therefore being too far from the load. (again shoot me now if I am talking nonsense)

If you look at some of the regulation modules that Paul HYNES does, they all seem to live close to the main PCB, inside the body of the TT.
Unfortunately I can't explain why this is considered to be a benefit, but I am sure someone here will oblige... (again this could all be nonsense, I am just reading various posts here, and trying to learn)

As per a 'Tracking pre-regulator' I am very excited to read Jim's thread when it is published.


Finally if you are looking for bespoke regulator modules that can be implemented easily within SL12xx on a tight budget, I would suggest this module I used myself succesfully...

http://theartofsound.net/forum/showt...ics-SL1210-M3D

It's easy and fairly cheap, and Brent is very pleasant and helpful!

[6L6]

Read this - it's fantastic - http://www.acoustica.org.uk/t/3pin_reg_notes1.html (4 pages)

I'm going to try the configuration on page one, with the zener reference. This is the one I've already made, but haven't installed it yet.

The tracking pre-regulator is the 2nd one to try, found on page 4

[Andrei]

I take my hat off!

You don't have a hat!

[Firebottle]

So I declare the free vinyl is going to Alan in France!

Francois you're a star, the vinyl arrived this morning. An excellent choice you made, as it has filled a gap in my music collection.
Very enjoyable and on 180g

Alan

[Frankyc2003]

No worries Alan,

I hope you enjoy it!

[6L6]

I have installed the first LM317 based regulator in my SL-1200. There is not a specific schematic in the article, look at the one on page 1 of the off-piste article, and all you do is replace R2 with a Zener reference and make sure you include C2.

I did mine point-to-point (on air?... I think the Queen's English and American English are different in this regard.) and covered up all in heatshrink as I don't want anybody copying me directly, do as I say, not as I do and all that...

It works wonderfully, sounds great, and took about 15min to install.


Here it is... not particularly exciting.


Lift the motor PCB and remove the old pass transistor and wires. (You could just cut the old wires and splice if you desire)


It mounts in the same position as the old transistor.


Don't forget some kind of insulator under the regulator - the old transistor was a 'full-pack' and did not need an insulator.


The regulator need to be grounded here, at the turntable center ground.


Schematic

[6L6]

I'm corresponding with a member who is wanting to do this mod, and have put together the beginnings of a parts list from Farnell -

Big caps - http://uk.farnell.com/panasonic/ecos...63v/dp/1198722

Diode Bridge - http://uk.farnell.com/multicomp/gbpc...00v/dp/1621681

Bridge snubber - http://uk.farnell.com/vishay-bc-comp...ial/dp/1215473 (Note that 5 is the minimum quantity. No big deal, they are 19p each) ((use one of these as the film bypass on the big caps as well))

Bleeder resistor (I'm linking to a different value than the one I used, this is better. )
http://uk.farnell.com/te-connectivit...2k2/dp/1751857

Filter resistors - http://uk.farnell.com/te-connectivit...10r/dp/1751825

[Qwin]

Hi Jim

The Farnell part links are very usefull for us this side of the pond.

Any chance you could do the same for the regulator?
(Even if instructions on how to build come at a later date).

Farnell have a min £20 order, so its cheaper if you can buy as much in one hit as possible.