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Thread: SL-1200 DC Power Supply DIY

  1. #191
    Join Date: Oct 2014

    Location: East Coast USA

    Posts: 73
    I'm Nathan.

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    Quote Originally Posted by Packgrog View Post
    Agreed. I'm certainly not comfortable doing these kinds of modifications yet. Well said on this one, Mike.
    For myself, not at the level that Khom is working at

    Quote Originally Posted by RickeyM View Post
    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
    Don't you all laugh at once

    We the willing, working for the unknowing, are doing the impossible for the ungrateful.
    We have done so much for so long with so little, we are now qualified to do anything with nothing.

  2. #192
    Join Date: Sep 2015

    Location: Minsk, Belarus

    Posts: 16
    I'm Valery.

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    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.
    Analog: Technics SL-1200MkII (rewired, external PSU, separated power supply for FG Amplifier, Control circuit and 3-phase Driver stage, improved bearing), AT-440MLa
    Balanced input J-FET DIY phonostage
    Digital: Cubietruck (headless Debian server, i2s output, external masterclock from DAC), content on HDD. DAC: Lynx D29v4 (Altera FPGA digital stream separator, 2*AD1853, 2*3 OP42 LPF)
    PA: class A Zen-4
    Acoustic: 3-way floorstanding cabinets with Visaton drivers

  3. #193
    Join Date: Apr 2009

    Location: Ayrshire, Scotland

    Posts: 93
    I'm Ian.

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    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][/IMG][IMG] Underside of sub reg board with two 3082 regulators[/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)
    Last edited by Ianmac; 12-01-2017 at 15:07.
    Technics 1200 tweaked,Ianmac Bearing, Sony CDP11, Caps 2 streamer, Benchmark DAC2, Hypex NCore, ATC SCM40
    SB Touch, CDP11,Benchmark DAC1 HDR, Hypex UcD 400. Kef 1point2 speakers. Ianmac Filters

  4. #194
    Join Date: Dec 2011

    Location: Athens

    Posts: 129
    I'm Dimmy.

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    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


  5. #195
    Join Date: Apr 2009

    Location: Ayrshire, Scotland

    Posts: 93
    I'm Ian.

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    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.
    Technics 1200 tweaked,Ianmac Bearing, Sony CDP11, Caps 2 streamer, Benchmark DAC2, Hypex NCore, ATC SCM40
    SB Touch, CDP11,Benchmark DAC1 HDR, Hypex UcD 400. Kef 1point2 speakers. Ianmac Filters

  6. #196
    Join Date: Dec 2011

    Location: Athens

    Posts: 129
    I'm Dimmy.

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    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.

    Screen Shot 2017-01-12 at 02.06.06.jpg

    Sure, if you send your circuit I can work something out
    Last edited by dimkasta; 12-01-2017 at 14:59.

  7. #197
    Join Date: Apr 2009

    Location: Ayrshire, Scotland

    Posts: 93
    I'm Ian.

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    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.
    Technics 1200 tweaked,Ianmac Bearing, Sony CDP11, Caps 2 streamer, Benchmark DAC2, Hypex NCore, ATC SCM40
    SB Touch, CDP11,Benchmark DAC1 HDR, Hypex UcD 400. Kef 1point2 speakers. Ianmac Filters

  8. #198
    Join Date: Apr 2009

    Location: Ayrshire, Scotland

    Posts: 93
    I'm Ian.

    Default

    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.
    Technics 1200 tweaked,Ianmac Bearing, Sony CDP11, Caps 2 streamer, Benchmark DAC2, Hypex NCore, ATC SCM40
    SB Touch, CDP11,Benchmark DAC1 HDR, Hypex UcD 400. Kef 1point2 speakers. Ianmac Filters

  9. #199
    Join Date: Sep 2015

    Location: Minsk, Belarus

    Posts: 16
    I'm Valery.

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    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.

    FG_reg.jpg

    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.

    6680_diagram.jpg

    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.
    Analog: Technics SL-1200MkII (rewired, external PSU, separated power supply for FG Amplifier, Control circuit and 3-phase Driver stage, improved bearing), AT-440MLa
    Balanced input J-FET DIY phonostage
    Digital: Cubietruck (headless Debian server, i2s output, external masterclock from DAC), content on HDD. DAC: Lynx D29v4 (Altera FPGA digital stream separator, 2*AD1853, 2*3 OP42 LPF)
    PA: class A Zen-4
    Acoustic: 3-way floorstanding cabinets with Visaton drivers

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