Motor wiring on TD-125 MkI question

Discussion in 'Turntables' started by gkargreen, Jun 7, 2018.

  1. gkargreen

    gkargreen Active Member

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    working this up, cleaning, etc. and my blue wire broke off the pcb. I did not note which terminal it was connected to before it broke off, and cleaning each terminal in hopes of finding a piece of the wire did not work either. These damn boards seem to change with each one, I have looked at dozens of these board on google and each one is different, none quite matching mine. The only thing I have to go one is the board is marked blue wire, but there is also a brown wire coming from a transformer going to that same terminal and, as noted above, I did nt find any piece of broken wire. Any ideas? Thanks
     

     

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  2. tnsilver

    tnsilver Super Member

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    The German color codes are printed on the silkscreen on the conductor side of the PCB, but
    can get blurry or even wiped off:

    [​IMG]
     
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  3. gkargreen

    gkargreen Active Member

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    Thanks Tom, that look just like my board, wondering why I have a brown wire from the transformer hooked up where the blue wire goes, any idea?
     
  4. tnsilver

    tnsilver Super Member

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    dunno. maybe someone had been there before. Normally, the AC power supply lines from the
    transformer hook up to the rectifier bridges and not directly to the motor feed.

    [​IMG]

    [​IMG]
     
  5. Blue Shadow

    Blue Shadow Waiting for Vintage Gear from this century Subscriber

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    Time to think about where the wires start and end instead of color
     
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  6. gkargreen

    gkargreen Active Member

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    482
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    Thanks, guess I need a schematic that sounds the wiring for my table. Tom, the schematic you show doesn't match my pcb, but the first pic looks just like my pcb with the caps and the single rectifier.
     

     

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  7. gkargreen

    gkargreen Active Member

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    Hi Tom, here are the pics to follow. There was no problem with the board, other than finding the values of the caps so I can restuff the board, as well as clean the adjustment pots. I think what happened was that the wire broke loose when I flipped the board over. So it appears that the brown wire is also attached to the middle/blue terminal on the pcb, from teh schematic that should be the center tap of the transformer, correct? I can measure that out to make sure. I appreciate all the help, and I am sure to need more as I bring this table up to full working order, I have a presentation at our radio/audio club meet and am trying to get the table ready for that, thanks!
     
  8. gkargreen

    gkargreen Active Member

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    482
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    photos... DSCF6656.JPG DSCF6657.JPG DSCF6658.JPG the blue wire from the motor is just hidden by the board in these pics....
     
  9. gkargreen

    gkargreen Active Member

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    482
    Location:
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    Tom, want to thanks you for all your help! I do have a few more questions, what do you recommend for the grease/oil in the bearing well, the original looks like some kind of grease. Also, I did hook up the blue wire and turned the table on and it works fine, although the speed locks in with the control all the way to left/+ side. And while the table runs, the torque is pretty weak, doesn't take much to slow/stop the table from rotating, is this normal? Finally, the motor mounting screws, one of them had a spring mounted under it, is there some procedure to adjust the screw to orient the spindle in some fashion? Thanks again.
     
  10. gkargreen

    gkargreen Active Member

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    Thanks Tom! I am running these fixes down that you gave me, will let you know how they work out. One question I have is the three bolts that hold the top plate to the bottom plate, they have the little gray rubber washers on them, is there some amount of bolting together that I should do when reassembling them? Do I torque the nuts all the way down on those?
     
  11. gkargreen

    gkargreen Active Member

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    Tom, do I need to have the turntable sitting in the operating position and with the platter running to measure the voltages? Thanks!
     

     

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  12. gkargreen

    gkargreen Active Member

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    oops, and making the pot adjustments?
     
  13. gkargreen

    gkargreen Active Member

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    No worries about the voltage measurements, I do a good bit of electronic restoration, haven't done many turntables though. The service manual I got of the 'net wasn't very clear or quite complete may need to get the one from here on AK...
     
  14. gkargreen

    gkargreen Active Member

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    482
    Location:
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    Hi Tom, have been working on this, got the new caps in and when I run the table I noticed a "dip" to the platter as it rotates. Later I saw a marking on the outer platter saying "low" but I notice a dip on the inner platter as it rotates. What clued me to this was a little wobble in the timing display (for want of a better word, the speed dots that are adjusted to be stationary by the speed control). Is this a "killer" for getting this table to operate correctly and/or to perform to its best performance level? Thanks, Randy
     
  15. Blue Shadow

    Blue Shadow Waiting for Vintage Gear from this century Subscriber

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    The dip on the inner platter could be a bent shaft. If that is the case a replacement inner platter sourced from the bay might make the table correct again. You need to look at the movement of the inner platter and verify if that is the case or if the bushing in the table is damaged. This part is replaceable on the early 125s.

    This issue needs more investigation otherwise Tom would not have used the dunno above.
     
  16. gkargreen

    gkargreen Active Member

    Messages:
    482
    Location:
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    Thanks Tom & Blue, just got back in town and had a good look at the platter spinning and indeed there is a noticeable dip in the strobe when spinning, I confirmed that the inner platter, when spinning, does indeed slightly dip from a visual true looking at the edge of the inner platter, so a bent shaft may indeed be the issue. FWIW, if left in what affect to the sound would such a dip have on playback, a bit of "wow" perhaps? I am going to start looking into a new platter just in case.
     

     

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  17. gkargreen

    gkargreen Active Member

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    482
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    OK Tom, I will take a close look to see if the bearing well is mounted wrong or any cracks in the sub-platter, I agree it would seem difficult at best to bend that shaft, but I have seen stranger things!
     

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