DIY power supply for Technics SL1200/1210

The KAB external power supply for the Technics provides a regulated 34V DC that goes to the internal diode bridge. The deck's own regulator on the main circuit board drops that down to 21V. I decided to make a regulated 21V supply and bypass the internal reg completely.
I downloaded the circuit diagrams from the Technics forum at Vinyl Engine, and saw that it would be possible, by cutting a wire link, to attach the new supply without having to remove the circuit board. (Referring to the page showing the Drive Control PCB, I cut the vertical link near the top of the board, just left of the word 'Technics', and connected the 21V DC to the lower part of that wire. The earthing point is at the bottom corner of the board. The page from the manual shows the underside of the board, but of course when you remove the platter and the plastic cover you will be looking down at the board from above.
Connecting the new supply in this way disables the strobe light and the cueing light. I've never had much use for either of them, so that was fine by me. If you want to keep them, it's not too difficult to find a different way of connecting it up. (See below - Post no.10). My way of connecting also in effect eliminated a supply bypass cap C3, so I attached another one.
My first impressions are positive. Not a dramatic difference, but more spacious and with a quieter background.

John

Interesting, John. Can we see some pictures of your work? :)

Marco.

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Originally Posted by Marco

Interesting, John. Can we see some pictures of your work? :)

Marco.

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Sorry, haven't got a working camera at present.

John

That's a shame, John. Perhaps you know someone who does? The D.I.Y threads tend to work best when there are accompanying pictures which show work completed or in progress.

Interesting that you thought the external PSU didn't make a dramatic difference. Adding the KAB one to a 1210 in my experience (and others) certainly does - it quite simply transforms the deck and moves its performance to another level :)

Marco.

Marco - My listening impressions are at an early stage - and I must say I find that sort of thing difficult unless I can do side by side comparisons. It would be possible to create of way of switching between the two supplies but I don't think I can be bothered - too busy listening. ;)

Regarding the possibility of pictures, I think that it's really preferable anyway for people to understand what they are doing, rather than follow a 'soldering by numbers' guide. After all, this project involves mains voltages and I wouldn't like anyone to frazzle themselves as a result of attempting to copy what I did.

Anyway, the wire link that I snipped can just be seen on the first picture in this sticky:http://theartofsound.net/forum/showthread.php?t=1020 It's on the side of the board that is nearest the back of the deck, near a white connector. The earth point can be seen in the next picture, at the corner of the board, below AC terminals 1 and 2.
John

As the new PS settles down my impressions are that the sound is improving further. I'm using the standard, unmodified Technics arm, by the way, with a Sumiko headshell and Denon DL110. Standard rubber mat, no other mods.

John

A bit of further info that may help anyone who is thinking of trying this: I measured the current drawn from the 21V dc supply. On starting and stopping the current peaks briefly at 400mA (450mA at 45rpm), and settles to a steady 170mA when the table is rotating.

I used an 18V AC (two 9V windings joined in series), 75VA mains transformer and a L200 regulator on a heat sink. A 1.5amp LM317 reg should be OK too.

John

Wish I had a TT, plenty to keep a tinkerer like me busy:lol:

Seriously though I'm surprised theres not a lot more of TT diy on the forums to say how popular they are

Sounds like your having fun John, keep us updated

Leo

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Originally Posted by leo

Wish I had a TT, plenty to keep a tinkerer like me busy:lol:


Leo

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Well better get one double quick! If you're like me you may start to wonder why you bought so many CDs. :scratch:

A few pictures coming up.

First, though, I very much now agree with Marco that the PS mod lifts the deck to another level. As I listened to a wider range of music and the new supply bedded in I was more and more impressed. Significantly more dynamic contrasts, more solid and deeper bass, more focus in the mid and treble.

Prior to taking the pictures, I briefly reverted to the original supply. (Yes, this mod is easily reversible.) It was like a blanket damping everything down and sucking some of the life out of the music. I won't be going back there again!

By the way, if the loss of the strobe troubles you, and you think you may lie awake at night wondering if your table still rotates at exactly 33.3333...rpm, fear not. The original supply still connects to the driver for the strobe leds, so you can have the tt rotating via the new supply and simply plug in the original supply and switch on as before to get the strobe working. So you get a free strobe disabler thrown in! ;)

The first picture shows the vertical wire link near C3, which has been snipped.
The -ve lead of the new decoupling cap is connected to one of the test points. It is marked G.
The new PS lead will enter near the original mains lead. There is a convenient hole in the metal plate, which I have enlarged.

The second pic shows the +ve supply wire and the +ve lead of the decoupling cap soldered to the lower part of the snipped wire link. You need to make this joint fairly quickly, since you don't want the wire link coming unsoldered from the board.

The last pic shows the -ve supply lead connecting to the earth point at the bottom left corner of the main board. Abrading the surface of the metal lug slightly will help the solder stick. Blurry pic, but you get the idea...

It's fairly simple to do, but first do please check with the circuit diags. so you understand what you are doing.


John

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First, though, I very much now agree with Marco that the PS mod lifts the deck to another level. As I listened to a wider range of music and the new supply bedded in I was more and more impressed. Significantly more dynamic contrasts, more solid and deeper bass, more focus in the mid and treble.

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Excellent, John. I'm glad your PSU is doing the biz now it's running in. I was a little surprised at your earlier reticence ;)

The effect of power supplies is just *so* fundamental in all areas of hi-fi. As far as the 1200/1210 is concerned the fact is you haven't 'heard it' until you've added a decent off-board PSU!

Marco.

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Originally Posted by Marco

The effect of power supplies is just *so* fundamental in all areas of hi-fi.

Marco.

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It would be interesting to hear from someone with more circuit knowledge than I have, regarding the technical merits of the internal 3-transistor regulator in the Technics deck. Anyone?

John

genuine congrats to you jonners. I wish I had the brains/balls to take a soldering iron and a set of snips to my kit in the search for improvement. Alas I don't. The saving grace for me is that you have started to notice a real improvement with a psu. My ps1200 should clear customs soon and I'm glad to hear it wasn't £2mil wasted

Thanks, Muffinman. I've just heard that the Barking Audiophile Tax has been revoked so your final bill will be considerably less than £2m. :) Give the new supply a bit of time to settle in and I think you will be well pleased.

John

I see that Sound Hi Fi have recently posted details of their SL1200 power supply on their website. Interesting to see that they are critical of the internal regulator in the deck, and their approach is also to bypass it completely: http://www.soundhifi.com/sl1200/SL1200%20PSU.htm

John

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Originally Posted by jonners

I see that Sound Hi Fi have recently posted details of their SL1200 power supply on their website. Interesting to see that they are critical of the internal regulator in the deck, and their approach is also to bypass it completely: http://www.soundhifi.com/sl1200/SL1200%20PSU.htm

John

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Impressive.

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Originally Posted by jonners

I see that Sound Hi Fi have recently posted details of their SL1200 power supply on their website. Interesting to see that they are critical of the internal regulator in the deck, and their approach is also to bypass it completely: http://www.soundhifi.com/sl1200/SL1200%20PSU.htm

John

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It would be very interesting to compare it with the KAB PSU; I know how significant the effect of that is on a 1210. I think I might make a trip to Sound Hi-fi at some point and bring my KAB-modified deck along to compare with their modified version. I'm sure the exercise would be educational for both parties ;)

Their Jelco S-shaped detachable tonearm (shown in this month's HFW) also interests me.

Of course I would also do a full write-up of events on the forum :)

Marco.

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Originally Posted by Marco

It would be very interesting to compare it with the KAB PSU; I know how significant the effect of that is on a 1210. I think I might make a trip to Sound Hi-fi at some point and bring my KAB-modified deck along to compare with their modified version. I'm sure the exercise would be educational for both parties ;)

Their Jelco S-shaped detachable tonearm (shown in this month's HFW) also interests me.

Of course I would also do a full write-up of events on the forum :)

Marco.

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All the Jelco arms look interesting:

http://www.jelco-ichikawa.co.jp/e_tone_arm.htm
http://www.jelco-ichikawa.co.jp/img/...m-sa750_01.jpg

Yep, it looks a bit more 'substantial' than the Technics arm. I've no idea whether or not it would sound any better, though. I guess there's only one way to find out!

Marco.

is there a schematic for a DIY PS?

i'm wondering if there was something at DIYaudio on this?

i'm gonna check it out straight away

Anubisgrau,

Don't know about a D.I.Y PSU, but Sound Hi-fi do a rather nice one which I'll be checking out tomorrow along with the Jelco arm above :)

Marco.

yep nice, but a nice price too - it really makes me wonder is it all really worth it when you can buy a SP-10 with a decent arm (like AT 1012 i've seen recently) for around 1000E with an acceptable plinth....

or like this, with SME II in a funny board -cum- plinth:)

http://cgi.ebay.de/TECHNICS-SP-10-MK...1%7C240%3A1318

I'm very interested in hearing your reports on the new soundhifi psu marco. If it 'blows the ps1200 out of the water' please don't tell me - i've only had it in a couple of weeks :(
I thought i'd got my deck all pimped then someone comes along with the new black. whatever happens, i'll be sticking with my current setup for a long while yet. as good as the new improvemnets may prove to be, i have plenty of goodness in my 12 to keep me going for a while

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Originally Posted by anubisgrau

is there a schematic for a DIY PS?

i'm wondering if there was something at DIYaudio on this?

i'm gonna check it out straight away

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You can simply use a standard 1.5A variable voltage reg. IC such as LM317. This is what the Sound Hi-fi unit apparently uses. Schematics are everywhere - look at the data sheet for starters. Also see post no. 7 in this thread.
John

What is the advantage of working around the existing regulator-couldn't you plug in an outboard 34 v dc at, say, C1, thereby maintaining the strobe and light? It seems this would be better than keeping the stock ps for the lights only, since you've then eliminated the advantage of moving the transformer out of the chassis.

not questioning your methods-I don't know much, just here to learn.

frogspit -

Yes you could certainly connect a 34V DC supply as you suggest, or at the rectifier diodes as KAB do.

The advantage of bypassing the internal reg is that its performance is not considered to be all that great - evidence of that can be seen here:http://www.soundhifi.com/sl1200/SL1200%20PSU.htm
I haven't compared the sound performance of these two approaches, though.

I never use the light or the strobe so I don't connect the stock power supply at all. But if you want to keep the light and strobe and still bypass the internal supply including the regulator you could connect a 21V DC regulated supply in a different way: Just remove the wire that leads from the emitter of Q1 to J3, and connect the 21V at J3.

John

The strobe still works with the Sound Hi Fi mod. The best of all worlds?

Dave

Fast, too!

I'm working on my own SL-1200 MKII mods-I'd noticed that the specs matched the SP-10 MKII, so I'd thought I'd give a try at building a 'poor boy SP-12'. To that end, I bought a used and (relatively) inexpensive deck, and I'm giving it a go. My objectives:

*new plinth

*ability to use two arms, including a 12"

*outboard ps

*ability to turn strobe on and off (I'm using a toggle on the rear of the ps for main power, and converted the switch on the strobe to turn the strobe on and, yes, off)

*eliminate pitch slider

I'll be veneering it with maple to match the solid maple ps case.

BTW, the walnut plug above the strobe hides access to the 'VR301' which I moved off the pcb-this will allow me to tune the speed while the platter is turning, or even with the stylus in a groove.

Question: before I veneer, does the stylus light actually work? i.e., does it illuminate the outside grooves well enough to drop needle to record in a darkened room? I'm rethinking it's implementation here, but if it's useful, I'll probably maintain it.

Dave, I'm sure your ps is wonderful, but I'm seeing what I can do here with as much diy as possible. So far, since I had the materials around, cash out of pocket has only been the price of the tt-150.00US. With IEC and umbilical connectors, footers, new ps parts, etc., I'll probably be around 250-300. Not counting tonearms, of course.:)

i actively use my cueing light (i'm not scared of it degrading sound) and it does the trick.
your project looks great - can i put my name on the list for one?

Thanks 'muffinman'-

The light shall stay.

I like the resemblance between your pooch and my 'Mack' record weight.:)

Hi Mr Frog

There are fundamental differences between the SP-10 and SL-1200, in fact there is actually no similarity at all. However with a new platter, a modified main bearing and new control electronics they could get close.

Putting the SL-1200 into a new plinth is a splendid DIY project, well done! Is this the first time?

I would suggest that you fully screen all the wires from the motor, I assume you are remote mounting the electronics too? There is a lot of hash that your cartridge could pick up from unshielded wires.

In my other life in Weather Satellites www.time-step.com I encourage DIY's and help them. They in return often provide the inspiration of wood and trees. You can see on www.SL-1200-MK2.com that I explain in great detail how I do things, this can make it easy for a DIY'er to copy, and I'm not against that.

In a few months I will release the motor dynamic mod for all to have for free.

But it must be remembered that some people struggle to solder a single joint, and that I need to pay my mortgage just like everyone else. And that works well!

Keep up the good work!

Regards

Dave

Very nice, frogspit. Put me down for one too - ;) I look forward to seeing how it turns out.
The cueing light certainly works after a fashion, but I've never had much use for it myself. I agree with muffinman that it's very unlikely that it could affect the sound.

John

Dave,

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There are fundamental differences between the SP-10 and SL-1200, in fact there is actually no similarity at all. However with a new platter, a modified main bearing and new control electronics they could get close.

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I suspect that the SL-1200 shares more genes with the SP-10 than you may think. I'd be very surprised if when National Panasonic launched the first SL-1200 in its full 'audiophile guise' that the SP-10 wasn't in their thoughts when implementing the design.

Anyway, a fully-modifed SL-1210 (like mine, for example) certainly gets very, very close, sonically - no "could" about it! :)

You yourself said that the 1200/1210 got 95% of the way there... Based on what I've heard, I'm not sure that last 5% is terribly significant ;)

Marco.

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Originally Posted by Dave Cawley

I encourage DIY's and help them.
In a few months I will release the motor dynamic mod for all to have for free.

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What a gentleman you are Dave :youtheman: May you pay your mortgage and much more! I will certainly be buying stuff from you in the not too distant future.

John

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Originally Posted by Dave Cawley

In a few months I will release the motor dynamic mod for all to have for free.

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Jolly decent of you Dave :clap:

Thanks for the encouragement everyone-this seems like a great site. I'll be looking for more advice vis-a-vis the electronic stuff at some point-right now, I just want to finish the deck, and have the platter spin at the correct speed. There'll be plenty of time for me to fry resistors down the road.:)

Not my first project-below is my 'reference' VPI (I made everything you see that's wood), a Papst-motored, three-arm belt drive deck, a Rek-O-Cut idler that, so far, I've stripped and polished, and will drop into a high-mass plinth, and a G301 that will receive a plinth made from a material that should be interesting-or, perhaps, "interesting".

Dave, I appreciate the sometimes disparate realities of helping the diyers, and trying to make a living!. So, any help you give is not expected, but much appreciated. Frank Schroeder of the famous Schroeder tonearms likewise provides help to diy-ers attempting to copy his arms-another great guy. I'm not sure what that 'motor dynamic mod' is all about, but I'm looking forward to it.

Oh, and I'm under no illusion that the SL-12XX series are anywhere near the SP-10s in any way other then the published specs (and even there, the 10 MKIII is in a class by itself). I just wanted to try a DD deck, and have a little fun at the same time. So far-mission accomplished. At least the 'fun' part.

I'm amazed that you would provide that information to be honest, and very pleased so a big thankyou to dave cawley!!

Fraser -

My offer of help was made to you personally via a PM, so I would prefer you to use that method if you want to communicate further about this, thanks.

John

Whoops sorry mate, taken to PM..

So nobody else tried a diy PSU yet?
I'm going to treat myself to one of these SL-1210's at some point, theres way too much fiddling for a diy bodger like me to resist:lol:
If a linear regulated psu is good enough you can try out a few variations, their p**s cheap and easy to knock up

Hi Frogspit (what's your proper first name?),

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Oh, and I'm under no illusion that the SL-12XX series are anywhere near the SP-10s in any way other then the published specs (and even there, the 10 MKIII is in a class by itself).

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Oh you'd be surprised, once it's been suitably modified ;) Have a read here:

http://theartofsound.net/forum/showthread.php?t=1023

Good luck with your project! :)

Marco.

just joined and came across this thread. Fantastic work frogspit! Can you give us an update? How does the new plinth and PS sound? What material did you use for the laminates - MDF? Any more pics?

Hello everybody,
This my first post here. I have been kicking around the idea of doing this for several years.
http://www.vinylengine.com/phpBB2/vi...248&highlight=
http://www.diyaudio.com/forums/showt...threadid=67240

Well I finally done it pretty much as I hinted in diyaudio, using tangents STEPS
psu. http://tangentsoft.net/elec/teps/

Its a shame he no longer stocks the circuit boards, but anyhow the the slightly more humble tread is very similar.http://tangentsoft.net/elec/tread/

tangent publishes ripple test values. http://tangentsoft.net/elec/psu-tests/

Here are some pics,
http://img10.imageshack.us/img10/9082/dsc01091n.th.jpg
testing.

almost final with old power supply taken out,
http://img31.imageshack.us/img31/1614/dsc01092p.th.jpg

I still need to rewire the on off switch but its not a priority. everything works
connecting j3 and gnd, like was suggested earlier on in this thread.

Great project Blueworm. Let us know how it goes.

I also built a DIY power supply for my Technics 1200 and to be honest I'm AMAZED at just how good it sounds!! I was scepticle at first because I really don't understand how powering the motor from an outside source can have an effect on sound quality but it does and the difference is HUGE!

I mean you could spin the record by hand and you would get sound so if it's already quartz locked on speed why the big improvement?

If anyone is on the fence about building or buying a commercial external power supply do it! It's probably the biggest improvement I've done to date and now I can't imagine listening to this turntable without it.

Now this is what analogue audio should sound like;)