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Sony PS-1800 problem keeping it activated.

Discussion in 'Turntables' started by Jereostereo, Jun 12, 2018.

  1. Jereostereo

    Jereostereo AK Subscriber Subscriber

    Messages:
    47
    Hello. Last weekend I stopped by an estate sale and spied a lovely Sony PS-1800 turntable, but alas the tag had already been pulled on it. After scanning the sale for a half-hour or so, my only purchase was a $7 sleeve of 70's baseball cards of dubious value (turned out it had a lot of nice cards, including five Tom Glavine rookie Topps!). Felling a little disappointed as I walked out, I noticed the fellow that grabbed the Sony happened to be loading his purchases into his truck. As I lingered, his receipt was visible and I saw he grabbed it for a puny $20. On a whim I asked if he wanted to double his money and he said yes! So off I went with the Sony.

    OK - enough backstory. Down to the issue at hand.

    It's a very nice table, and rather rare apparently. Unfortunately I can't get it 100% operational. It is turned on by flipping a toggle lever - to the right for 33 and left for 45. The middle position is "off". When I flip the toggle to either side, the lever won't catch and hold. When I release the lever, the tonearm lifts and returns and the machine is off. If I keep the lever in place with my hand, the table operates fine - the strobe is lit and the cool red "reject/off" light on the front of the plinth is lit. But as soon as I let up on the toggle - it flips back to center, the arm returns and everything turns off.

    From previous research regarding this table on AK, I see that it seems to be operated with magnets "magnetodiode" - something I'm not very familiar with. My basic question is - am I dealing with a strictly mechanical issue like a worn or broken piece that keeps the toggle from catching, or is some type of problem with these magnets or a sensor keeping the mechanical switch from grabbing?

    Any insight is appreciated. I am going to dig into it later today and being forearmed might help me. Thanks as always.
     

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  2. Jereostereo

    Jereostereo AK Subscriber Subscriber

    Messages:
    47
    Update - if I push the lever to activate the table, hold it place for about 5 seconds, and ever so gently let it return to the center position, the table stays on. So there is no issue with the lever catching and holding - that isn't how it works. Is it possible the magnets are getting weak after 50 years? Do I dare spray a little deoxit around that part of the mechanism? My plan is to let it run like it is for a a few days of steady use and see if it regains it's sea legs. I am more than willing to treat her gently.

    By the way - fantastic table. Very quiet and smooth, and gorgeous to boot. A quality Sony product.

    Murphy's Law - these discoveries never take place until after the thread is submitted. Thanks for your indulgence.
     
  3. absolon

    absolon Super Member

    Messages:
    2,201
    Location:
    Lotusland
    I had a PS1800A with issues as well. It was a while back and my memory of it isn't 100% but I'm fairly sure your problem is more likely to be the catch. The magnetodiode mechanism is for activating the return, not for holding it in running position. As I remember, some judicious use of a file to ever-so-slightly reshape the worn catch mechanism for the spring motor that operates the return was required to get it to operate correctly but be careful. It is easy to overdo it.
     
  4. Jereostereo

    Jereostereo AK Subscriber Subscriber

    Messages:
    47
    OK - thank you. It has stopped working again. Sometimes plays halfway through an album side and shuts off randomly, or most often shuts off as soon as I release the lever. I still am not certain if the lever is supposed to stay latched to the side, or if it is designed to toggle back to the center position after activating the selected speed.
     
  5. absolon

    absolon Super Member

    Messages:
    2,201
    Location:
    Lotusland
    I can't remember the specifics of the mechanism.You're going to have to open it up to find out. It should become obvious once you do and if you can't determine, post some pictures.
     
  6. Jereostereo

    Jereostereo AK Subscriber Subscriber

    Messages:
    47
    I did indeed open it up yesterday and determined what the problem was. A thin piece of foam that provided counter resistance to the lever that rested against the shutoff magnet had completely deteriorated. I sliced a very thin sliver of magic eraser, about half the size of a postage stamp, and glued it over the lever. It allows the proper pressure to hold the lever over the power switch, but is pliable enough so when the shut off magnet activates and pulls on the lever, it disengages and allows shut-off.

    It was a lot of kitchen table diagnosis and minor operation, but it will hopefully keep this beautiful and rare turntable spinning albums a bit longer. Thank you absolon for your help.
     

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  7. absolon

    absolon Super Member

    Messages:
    2,201
    Location:
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    Well done!
     

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