Sorry for the late answer.
I do not have any right now, but I can order some. I have a new set designed that works very nicely and is far more flexible in part selection.
PM me if you are still interested
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Sorry for the late answer.
I do not have any right now, but I can order some. I have a new set designed that works very nicely and is far more flexible in part selection.
PM me if you are still interested
Bump.
Anybody build a PSU from this thread lately?
I did, about a couple of months ago. I'm about to take it the rest of the way and build the voltage regulator.
I'm tidying up an external PS for a buddy, I've made the Cap board and regulator (all tested good), but have been searching all afternoon to see where it's connected :-(
Anyone got any pics of it completed?
I found a schematic that recommended removal of R3, R4 and C3. Cant find C3, so location would be helpful too.
Have you seen this post--? http://theartofsound.net/forum/showt...947#post459947
Hi Jim,
been through lots of posts, my confusion is taking over where Andy left.
He made the external TX mod. With my (slightly) better tech skills I've inherited the job to build and install your regulator and cap bank.
Found this, is it correct?
https://farm9.staticflickr.com/8715/...7c85305a_o.jpg1210input by levs the diver, on Flickr
The start of this thread the pictures show a different board lay out. D1 is an odd 4 legged component .https://farm8.staticflickr.com/7727/...96959f05_o.jpgIMG_1835 by levs the diver, on Flickr
I have an SL1200 MkII that I'm not ready to start tinkering with. It performs very well and looks good for its ago.
However I do have an SL1100 that I'm willing to play with even though it too is in good sonic and cosmetic condition.
Can a separate power supply work with the SL1100 also? Do you think it would benefit in a similar manner?
The PSU is somewhat similar, it certainly will make a difference to externalize things. Also, considering it's age, you might want to do a complete re-cap. They are 40+ yr old.
In my experience, getting the transformer off the plinth and away from everything is at least 75% of the mod, and completely worth the effort. Give that a go, you'll be very impressed by the improvement.
Anybody do this mod lately?
Just finished my 1200 today.
I used the LM series regs (individual and pre reg versions), some time ago and moved to the LT family last year, initially building a reg very similar in principle to the ccts shown here.
My recent version uses 4 regs, two main and two sub.
The main 2 regs feed the 1200 board.The board is divided ( electronically) into two sections one the Motor drive circuitry and the other the Control circuitry so the current hungry motor load is separated from the more sensitive Control circuits.
The two sub boards are not essentials but add some icing to the cake by supplying two sections of the control circuit where the original Technics regulation can be improved. (there is a little more detail in my last two or three post in the Ianmac bearing thread.)
It performs extremely well.
The LT family of regs have a few advantages over the older LM's, lower Dropout voltage (almost 1/2), 90 db ripple rejection, lower noise, smaller component count. Im using an 18 0 18 v transformer ,rating 80va, so have a good 3v headroom and well within the 1.5v needed by the LT so no hassle with transformer regulation, input mains voltage variation and supplying the peak current for the motor.
Unreg DC from the PSU / transformer box uses the old mains cable to get into the Techie, the dual regs are mounted on a small heatsink/mounting bracket in the old transformer recess. My two sub regs are mounted on a small PCB held on the two screws the held the original power transistor heatsink.
Again this performs well and lifts the techie to another level. Way beyond my LM pre reg /reg incarnation of a few years ago.
These are an easy build but some main PCB track cutting is involed ( two tracks). I used SMD versions of the LT regs for the sub reg boards but a conventional reg could be found if the soldering proves to be issue- it really isnt if you can hold the reg in place while you solder.
If there is enough interest and we have someone who could make PCB's I could sort out the circuits, basic layout and heatsinking. The two main regs barely get warm.
Ianmac
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.
Dimkasta
many thanks for the links.
Ill knock together a cct that will let me do this. The Cal output my Tek scope with a Low Z output driver might do.
Ian
You can do it with a generator signal. You jus tneed a resistor in series with the secondary. Check this link
http://www.diyaudio.com/forums/power...ml#post4206768
Sent from my HUAWEI NXT-L29 using Tapatalk
There's no question that the .22uF on the secondary is non-optimal. That said, it's better than nothing... :)
I love the work you are doing on this! Well done!
Sorry if I sounded harsh or demeaning there. Not my intention :)Quote:
Originally Posted by 6L6
No insult taken. :)
I'm actually quite happy to see a real measurement taken, the beauty being that once the value is known, it's pretty safe to assume that most of the transformers over the production run are likely identical, or at least close enough that those snubber values will be able to be used by all. :D :D :D
Exactly my thoughts :)Quote:
Originally Posted by 6L6
Another interesting idea for those that do not want to fiddle very much with special chip regulators is just replace LM317 with its slightly bigger brother the LM350.
According to the datasheet, with the compensation cap in place it typically has ~22db better ripple rejection (64db vs 86db), and 3 times less RMS output noise (0.001 %Vo against 0.003 %Vo) up until 10KHz
Surprised there is no interest in this.
Dimmy has forwarded suggested improvements and my own regs, based on Linear Technology chips offer a similar performance, easy to build with low component count. (6/7 per regulator)
Splitting the supply to drive control electronics and motor drive electronics with separate regulators placed close to the Technics PCB is a very good upgrade.
This is not over engineered so very cost effective.
I'm quite interested! It seems to be a well thought out mod and I'd love to try it. :D :D :D
Modding my -1200 is about 5th on my current list of projects, I've got the Pass Sony Vfet guide to write, my SP-10 to complete, the ZenMod "Iron Preamp" to build and make a guide for, the subwoofers for the Linkwitz LXmini speakers to make, and build the Stuart Yaniger "Equal Opportunity" valve phonostage. So actually 5 things in front of it. :eyebrows:
Is this something worthwhile to do if I'm using the stock transformer? If so, I'd be interested.
Yes, absolutely!
There's nothing at all wrong with the stock transformer, the issue is that it's mounted IN the turntable... Mounting it outboard and moving some of the noisier electrical bits to an external chassis makes a huge difference in noise floor.
Externalizing your PSU is the single biggest mod you can do to the table. And if DIY, the bang-for-the-buck is totally off the scale. :D :D :D
I guess then it's time to mount my PS in a proper enclosure. The wooden box it's in now looks more like a beginner science fair project :D
After bying SL-1200MkII first of all I removed Q1 and created LM317 circuit and then, of course, moved transformer to external case. Both actions was absolutely necessary, but not enough and I decided to make some additional work with all power lines - first of all to split driver and control powers as described on this forum.
Attachment 18963
After that I found one more weak point in schematic. It's FG amplifier Q203 powered through simple RC filter from the same source as control IC's. Some strange fluctuations of FG output spectrum were observed under 10 Hz (NOT a 4.5 Hz @ 33 rpm). I can't understand (and still can't) how this mode appears but I observed it clearly until FG amplified power line separated.
So, now I have (see photo below):
- external primary stabilizer 26 V
- two secondary stabs (21 V each) which feed motor driver and control circuit separately.
- improved onboard stabilizers for IC's 6680, 6682 and 4011 ((typical LM317 and 78xx schematic, two left red circles)
- additional stab (78L09) for FG amplifier (right red circle). Btw, this amplifier is very simple and can/should be upgraded, my Tektronics shows very noisy and unstable sinusoidal figure coming to PLL circuit.
Attachment 18964
I made these changes in short time and of course they are not optimal, output voltages should be corrected for each stabilizer. But in general I'm sure it's correct way to improve Technics before any other electrical changes. Power is food for all Tech electronics!
Will further power supply improvements give us sound profit? Who knows... my opinion - no. No issues to make shunt regulator instead of series (I use shunt regulators in my DIY phonostage) or use some superstable schematics etc etc, but I think it's time to think about PLL parameters. Will be useful to find out some way(s) to observe in realtime platter speed fluctuations. I tried to analyze fg amp. signal spectrum as well as 3150 tone spectrum and although I'm not quite satisfied by my measurements, I can see real improvements.
Unfortunately I didn't read this topic earlier, this could save my time :)
Very nice. Do you mind sharing more info on how your extra onboard stabilizers are connected?
Yes, it's easy. The main goals was increase power stability, separate power for all sensitive schematic parts and to get regulators as close as possible to the end consumers.
1. 78L06 regulator feeds 4011 IC. R304 and Zener D301 removed, 78L06 ground pin inserted instead of D301 anode, IN and OUT pins inserted instead of R304.
2, 3. 78L05 (not 78L09 as stated in my previous post) regulator feeds FG Amp. R221 removed, 7805 GND pin inserted into new drilled hole. 3rd screenshot captured from SL-1200 datasheet and shows exact place for drilling because of hole should de drilled througn PC board ground wire.
Additionally I reduced R216 resistance from 150k to 100k, because of FG Amp. supply decreased from approx. 9V to 5V and Q203 mode should be returned to linear amplifying. I plan to increase power back to 9 V in future.
4, 5. LM317 regulator feeds both 6680 and 6682 IC's. Q201 replaced by LM317 with datasheet's schematic, several unused components removed. Output voltage adjusted to 9.5 V. So, now 6680 makes only his main work - speed control.
As you see, I used enough simple solutions. LM317 with resistors will be better to place on separate small vertical subboard, maybe it will my task in future. I'm not sure whether more complicated schematic give effect or not, maybe I will replace some regulators to improved ones. But now I have significantly better sound and Technics makes me happy.
Thanks. I'll have a closer look when I'm back from my vacations
Folks,
Refering to modifications of the main PCB
Khom: says: "Yes, it's easy. The main goals was increase power stability, separate power for all sensitive schematic parts and to get regulators as close as possible to the end consumers."
It may be easy for those of us who are experienced in electronics and circuit work!
However if you are not familiar with doing this type of work then get someone who is, to do it for you.
We have been around this loop before.
A simple mistake can cascade into a lot of trouble and a badly damaged PCB.
Good point MikeQuote:
Originally Posted by Mike_New
Khom
Thanks for your info.
Im just back from the New Year Break and need a little more time to study your tweaks.
Initially I sorted out an alternative mains transformer with a higher VA rating(I run 240v 50Hz mains here in the UK) with an LM regulator. I upgraded this to a floating pre reg circuit then last year changed completely to Linear Technology regulators.
Im currently running with an 18-0 -18 80VA Torroidial transformer separate from the Techie feeding unreg DC to two LT301 regs fitted into the Techie old transformer hole . These separately drive the signal electronics and the control electronics. I have two sub regulators used as a replacement for the Zener D301 and Q201. These use LT302, a 200ma version of the 301 famility
I need to mod a platter so I can run the deck with various loads and scope the electronics freely.
I have more work to do, just need more time.
Agreed. I'm certainly not comfortable doing these kinds of modifications yet. Well said on this one, Mike.Quote:
Originally Posted by RobbieGong
For myself, not at the level that Khom is working at :stalks:Quote:
Originally Posted by Packgrog
Don't you all laugh at once :DQuote:
Originally Posted by RickeyM
https://photos.smugmug.com/Component...104_1391-L.jpghttps://photos.smugmug.com/Component...O/104_1389.jpg
Of course, I do NOT recommend to make any changes in Technics PCB without some experience in electronic devices upgrade (it's well, when everything is going well, but what if not?). Moreover, because of my mod based on idea described by Leo here Technics 1210 internal regulation mods, my improvements can't be realized without his power supply splitting.
Really my description is enough to replace and upgrade onboard regulators. But I'm ready to get answers to any questions, add photos etc. etc. I didn't used some secrets or know-how.
I think that separating power supply is absolutely necessary but not enough because of FG amplifier remains powered from the same source as control IC's. That's why I did made my mod.
Khom
Ive now finished building my phono pre so I can concentrate on the PSU for a few days before I start another batch of bearings.
I am working along the same lines as you with IC302, IC301 and AN6680 so will turn my attention towards the FG Amp. Im interested in the spectrum you noted from the FG, it must be telling something about a rotational issue.
If you get a chance, try a deliberate unbalance of the platter and see what spectrum appears. Im still looking for a platter, at the right price, to mod so I can freely scope the electronics with the motor running.
My initial reaction is to simply remove R221 and replace the C216 end with a 9v reg supplied from my clean 21 v supply driving the control electronics. It is also my intention to reduce the physical size of my sub regs to make them all on board additions with, where possible, pin outs that match the holes vacated by redundant components. 1mm and 1.2mm vero pins are usefull to help achieve this.
The reg I need for the FG amp is almost identical to the one I use for IC 301(9.6v). I am using LT3082's for all my sub regs. This is in an SOT223 package and can easily be fitted and soldered onto 0.1" Vero board with the track removed under the 223 to stop P1 (set) and P3 ( In) shorting onto the output tab (also P2 Out) which is 3.2mm wide. Dependant on the techie components I can reuse I should get down to one or two resistors and one small C + the 3082, so the size could be quite small.
I'll keep you posted as to progress.[IMG]http://i824.photobucket.com/albums/z...FXT11673_1.jpg[/IMG][IMG] Underside of sub reg board with two 3082 regulatorshttp://i824.photobucket.com/albums/z...FXT11672_1.jpg[/IMG] Topside of sub reg board for two regulators.
To help those not too confident with electronics, if I can find time, Ill revist the possibility of an updated version of - 1.replacing the stock transformer with an external transformer rectifier box,- 2. Replace the Techie regulator , -3 adding a second regulator to split feed the Control and Power electronics (which will involve cutting one track on the PCB). Beyond that, using the sub regs Khom and I are talking about you will need to be happy with what you were attempting.
This raises the question as to whether anyone has tried using an SMPS supply which, using an off the shelf unit, makes replacing the stock Transformer a relatively simple task.
I am wary of noise/ transients etc emanating from some SMPS designs and how difficult these are to get rid off as they pass right through most regulators. It would need a carefull choice of supply.
Ill have a look at what Farnell and RS have to offer. I say SMPS since last I looked, off the shelf linear supplies were thin on the ground.
Any one tried an SMPS ( Switched mode Power Supply)
I have just received some new pcbs, testing a new layout with the snubber and some extra things for other low current applications. I also wanted to try a new fab.
So far so good. There are some minor issues but no functional problems so far.
I am still waiting for some stuff before I can fully test them though.
Sorry for the low quality. My phone is terrible at low light and I cba to get my proper camera out right now
https://uploads.tapatalk-cdn.com/201...94340de267.jpg
Looks great.
Makes using an external transformer +rectifier to supply an unregulated DC to the Techie a much simpler job.
Could use two of these myself for another project.
How are you going to make these available ?
Could you do a PCB for the LT 3081 regs if I supply the cct and layout Im using.
This would help make the PSU upgrade start to get easy.
If I find no issues on my testing, I can spare 8 boards from the ones I have now, for 5 euros a piece plus shipping. Just send me a pm.
Dimensions are 45x95mm (final ones will be 5x10cm) and caps are 25mm max diameter with 10mm or 8mm grid. Diodes can be TO220 or axial, and the snubber network is the one I posted a few pages back.
I also added an smd common mode choke placeholder, but it is rather irrelevant for our application.
The boards are leaded HASL, FR4, 1.6mm and 1oz copper.
If there is enough interest I will make more.
I am waiting for some more samples from another fab, so I might decide to go with a different color and 2oz copper for the final ones. ENIG is pretty much a waste of money if you are not doing robot-assembled SMDs.
I am also working on various versions of the 317 regulator. My latest board includes the 3 regs I am using currently, designed to be fitted right on the screws of the power entry hole, and on the nearby heatsink area. But I am postponing this for now until we decide what works best and is easiest.
Here's a preview.
Attachment 19053
Sure, if you send your circuit I can work something out
Looks great,
Ill get the info on the ccts I'm using to you as soon as I can via PM.
With PCB's available the whole job will be much easier and within the reach of more members.
Khom
Ive finished my new phono pre and and putting it to good use working with 2 decks to evaluate one with a bearing fitted with silicon rubber between the bearing and the bearing well wall and one without, add to that different oils so my head was nipping.
To get back to earth I spent this afternoon making two sub regulators for the FG amp.
I got the size down to about 14mm sq and have fitted it onto the main PCB with two plastic stand offs.
I have just fitted one and am listening to it now.
I have got to say +++.
Sonically it is a bigger individual improvement than the sub regs I fitted to the other control chips. I think with your feedback on the FG amp and the the combination of tweaks we have been discussing with Dimkasta we must be close to getting the rotating parameters of the platter as good as is possible ? ( wishfull thinging?)
I am running with an external transformer 18-0-18v, rectifier and resevoir Caps feeding unreg DC to the technics. This feeds two LT 3081 regulators, one feeding the Drive electronics , the second feeding the Control electronics. Three sub regs using LT3082's come from this feeding IC 302, IC301 and the FG amp.
AN6680 is still fed from the LT3081 via Q201, but Q201 is freed from supplying IC301 and the FG amp.
I have not replaced Q201 yet as I could not find a data sheet on the AN6680 , I wanted to know the current consumption to ensure the LT3082 was up to the job and a bit more about its internal stabilizer on P9 and P10. P9 looks like it has some control on the base of Q201.
I note on your photos that you had removed R202. Do you have any data on the AN6680 ?
Ill fit the second deck with its FG sub reg to morrow and report my progress- to date its very positive.
Hi, Ian.
I'm really wonder why Technics engineers missed that very important thing (pure power for FG amplifier). My solution has minor weakness - low output voltage (FG Amp. powered by 5V instead of 9). I think will be better to make further improvement: remove R221, put some 9V regulator (for example 78L09) and feed it from +19V regulator, which feeds also control IC201 (AN6680). See attached picture.
Attachment 19086
I haven't any doc's for AN6680 (maybe ask them from Matsushita :) ? I'm not sure to get positive answer), but as I see, LT3082 output current (200 mA) should be enough and it will work perfect (I love LTxxxx regulators). Of course external small PCB should be created. R202 is no more necessary becase of I don't use internal regulator circuits, see second attachment.
Attachment 19087
Measurements... I still can't find good solution. FG signal spectrum has wide peak and sidebands are almost invisible. I have Adjust+ test disk from Dr. Feickert but not satisfied them. And trial period for my spectrum meter software is finished. I'm looking for suitable tools but unfortunately my vacations are ended this week and I can't pay much attention to hobby.
To all. Gentlemen, I'm very sorry for such technical post but I don't see any other possibililty to discuss that important Technics SL-12xx things. I hope later we will make detailed "how to" description based on our common work and ideas. From my side I can promise do not keep any secrets.
Hi all,
What a great thread this! I've been visiting as a lurker over the years and was surprised to see it still running when I was looking to renew my faith in the sl-1200. I'm especially pleased and impressed by the neat work and continuous digging for more gold out of this magic machine.
I started my journey long long ago with an external supply. This evolved into a half wave choke input supply (two STTA-02 diodes) and elaborate filtering and regulation in the deck. The sound was devoid of stress and I enjoyed it a lot whilst ruining three expensive carts and decided that the cost of ownership for digital is lower and relayed my focus.
This summer I undid most of the electronic mods but this was too much of a step back. Recently I started again. To give you an impression of where I am now with the mods:
- mike new bearing
- SDS isoplatmat
- isonoe feet
- external transformer (2x24V, 50 VA)
- 1N4007 graetz bridge
- serious recapping: Black Gate NX on filter positions, STD on psu positions
- pulled the strobe light (brown) wire
- main regulator disconnected by pulling component pins
- LM 317 as 25mA CCS replacing R304
- LM 317 as 33.7mA CCS replacing R201
- LM317 generic 21V regulator with zener and LEDs at adj pin
- LM 317AH 8.7V regulator for the FG amp
- [EDIT] replaced the 4011 with a more modern version out of necessity
In the past I did loads of different stuff like power supply routing, regulator configurations and removing components. All adds up (or subtracts when not properly implemented) but I would say the externalization of the transformer and FG amp stabilization are the most fundamental electrical changes. Credits to this thread I have finally executed my long term plan to address the FG amp supply.
On the mechanical side the isoplatmat gets the honors.
some stuff I've encountered:
- the SL-1200 is super, super, super sensitive to power supply changes. Not everything works out for the better. Measuring is "inconvenient' and difficult. This makes component and topology selection somewhat of an art.
- LM 317 adjust pins are best lead to ground with zener and leds. A resistor may work but do NOT decouple with a capacitor.
- some components get really hot. I placed some chip coolers on them.
- my deck needs some warming up and sounds a little more stressed out in the end. Maybe I overdid the recapping and is some circuit oscillating.
There is a lot of rightness in the deck now and I didn't even externalize the rectification. Maybe digging up the choke input circuit would relax the sound a little more but there are many more opportunities to tweak. I'll keep you posted.
regards, Coen