It’s an SL1200 Power Struggle

…So since the “export” power transformer has just recently dried up in Japan, I wanted to figure the most economical and electrically sound and safe way to convert 120V AC Technics SL1200 turntables to 240V AC with the least fuss whilst still leaving them double insulated as per the original specification and Government regulations.

TestingI set one up and monitored its current draw under various conditions and the results were interesting. The original transformer provided 32VAC on its secondary at idle BUT as the current demand increased to the maximum the secondary voltage dropped to 27VAC..

Here’s the results for interest’s sake…
Primary Volts = 242VAC – Secondary 32VAC
AC current demand Idling – 350mA
Idling with lamp on – 430mA
Rotating at a constant speed with lamp on – 450mA
Stalling platter with lamp on – 955mA
Spinning backwards with lamp on – 1030mA
At full peak current demand AC drops to 27VAC

Not really an issue as the DC voltage required is 20V DC BUT I considered the peak current demands the motor circuit required during spin backs and stalling and observed a slight loss of recovery torque due to the poor regulation of the standard power supply compared to my test bench power supply.

Transformer detailI have found a modern toroidal power transformer that not only has a minimal electric field so as not to interfere with the close proximity of the motor circuit’s feedback windings but gave a slightly quicker recovery time as a power supply.

Ultimately I can convert export SL1200 to 240VAC and make them have better recovery from stalled at a very reasonable price and they look good.

Word!

Please use the contact form to enquire about converting or modifying your SL1200.

SL-AdminStay locked!

18 thoughts on “It’s an SL1200 Power Struggle

  1. hey. i jus got 2 tts from japan and pluged them in. they workd ok 4 a min then whent pop and smoke. do u thnk i stufft em up?

    how much 2 fix?

    • Hello Jed

      I see this a fair amount with imported equipment. People overlook the fact that Japan and the US use 120V power systems and plug their newly acquired gear in and watch it die slowly 🙁

      Unless an SL1200/1210 has the voltage change switch under the platter that allows you to switch from 120 – 230 volts, it will need to be converted OR run through a step down transformer.

      The worst part of your situation is the Japanese made SL1200/1210 don’t usually have fuses so they will slowly overheat the transformer until something gives up… hence the pop and smoke you observed. I would imagine the regulator circuit is also failed in the SL’s power supply.

      I am converting SLs to 230V for $115.00 each. Repairing the regulator circuit is only a few dollars more.

    • I’m sorry but I don’t know any SL repairers in Melbourne.

      Good luck with the dex and let me know how it turns out.

    • Hello 12-E
      I do but I believe you are in a country with 120V mains. The transformer I use has a 240V primary only and would be no use to you.

      Let me know if I am incorrect and I’ll give you the RS Components part number of the 240V version.

        • Hello Dennis
          I have these made by a local company so I can’t give an off-the-shelf part number. Remember too the Japanese models require a fuse holder and fuse fitted and modification to the snubber circuit to work in Australia safely.

    • Hey,

      I have a bit of a situation with one of my Japanese sourced 1200’s, and I’d like to just convert them both to save the hassle.
      I know an experienced electrician that would certainly be able to replace the transformer for me, but I’d just like to confirm before I approach him.

      Would you be so kind as to email me the part number of the transformer you use?

      Thanks!

      • Hello Shane
        I have these made by a local company so I can’t give an off-the-shelf part number. Remember too the Japanese models require a fuse holder and fuse fitted and modification to the snubber circuit to work in Australia safely.

  2. Hi. I am having a problem with my Technics sl1200 mk2. when i put it on the 33/45 light is on the platter spins. the light @ on/off does not light up. Any idea what could be the problem.

  3. Hello,

    I have two decks. One is a 1200mk2 and the other is a 1200m3d. They are both US versions and do not have the voltage switch in them. I have currently relocated to Hong Kong which uses 220v. I am looking for a simple solution to converting these as I would like to avoid using a step-down converter. How is your way any different from just swapping out a stock transformer and power board from a 1210? (there are some used on eBay.) I know you mentioned some benefits as far as torque is involved, but are there any drawbacks as to doing it your way? I am just a little skeptical on making mods as I wouldn’t want to damage anything for the long term or compromise any sound quality. Thank you for sharing

    • Hello Eun
      I only found an alternative to the Technics transformer because the original parts are no longer available. The small advantages I found are extra.
      The power supply in a Technics has nothing to do with the signal path so cannot affect the audio. The only issue could be the magnetic field of a poorly chosen transformer. The toroidals I use have almost zero magnetic field. If you can find Technics dual voltage transformers on Ebay I would use them as it will make it easier to convert back should you return to the US.

  4. Thank you so much!! How do you guys proceed with this conversion? After payment do you just send the parts and instructions? (I do have a small engineering background in broadcasting so I know my way around a soldering iron and a circuit board). I do find relief that you are doing repairs and modifications the right way. I have an appreciation for your craftsmanship. Thank you again and please let me know as this is the solution that I have been looking for (for a very long time!)

    • I am confused. I haven’t offered you anything accept advice. I don’t sell these parts as they need to be installed by an authorised electrician or engineer.

      I am sure there is an electronics repairer close you you that can convert these units for you.

      If you want you can get them to contact me and I can explain how I do it.

      • My apologies for the misunderstanding, and thank you for your advise. I am asking, if possible, can I purchase this service off of your website? And if so, what is provided? Is this something I have to send in to get done or is it like a kit that you send out? That is all I was implying by the last post.

        • ah. I see. I would need the dex here to convert. I have considered making it a kit but the dangers and risks are too great. Sorry.

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