Steve,
I'll check that in a bit, but something doesn't add up. The pin is stationary. It could be under spec and when loaded the idler shouldn't move. There could be an issue with azimuth, but again, this wouldn't cause the idler to move back and forth.
My brain says this is symptomatic of a faulty moving part not a faulty stationary part.
My gut says coincidence.
I'll check that in a bit, but something doesn't add up. The pin is stationary. It could be under spec and when loaded the idler shouldn't move. There could be an issue with azimuth, but again, this wouldn't cause the idler to move back and forth.
My brain says this is symptomatic of a faulty moving part not a faulty stationary part.
My gut says coincidence.
then the carrier bracket (and its locater pin and bushing are suspect of not holding the idler wheel securely.
see if you can find some slop in the carrier bracket shaft/bushing fit by trying to move the carrier bracket about by hand.
next thought; is the axle pin bent? remove it from its bracket and roll the pin on a flat surface to test.
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I've previously tried this and just now tried again. There is no slop.
And if there was slop something has to induce it to move. A wheel moving concentrically won't induce movement. The only way to move in the "slop" is to change the load by moving in a circle not concentric to the spindle.
Here's a little something more. I marked the idler with a felt pen. It wobbles the same way every time. If I disengage then reengage to the step pulley the idler wobble exactly the same way. I removed the black o-ring and installed the red one. The idler wobbles in the same location. I rotated the spindle. The idler wobbles in the same location.
I need to check the idler with the calipers.
And if there was slop something has to induce it to move. A wheel moving concentrically won't induce movement. The only way to move in the "slop" is to change the load by moving in a circle not concentric to the spindle.
Here's a little something more. I marked the idler with a felt pen. It wobbles the same way every time. If I disengage then reengage to the step pulley the idler wobble exactly the same way. I removed the black o-ring and installed the red one. The idler wobbles in the same location. I rotated the spindle. The idler wobbles in the same location.
I need to check the idler with the calipers.
where it gets me is that you originally indicated that both of your wheels exhibited the similar "noise". However just looking at the one wheel run out like that, I wonder if the other wheel operated the same? If not that would isolate the problem, one defective wheels. but if two wheels of different mfr show the same problem, then it goes deeper than just a bad wheel.
-Steve
I understand your skepticism, but stranger things have happened.
You must understand what I'm saying as well. There's only one thing moving here, and it's the idler. Everything else is stationary.
I'm having trouble understanding how a stationary element can cause the wobble.
I wish I had a third sample.
Fwiw I'd like to see a movie of the 2nd wheel running against the stepped pulley.
If the second wheel shows the same behavior... Then the carriage assembly isn't actually stationary. Even when correctly assembled the carrier bracket is in motion. There is a torsion spring that pressures the assembly. Necessary for good speed shifting. If the spring isn't tensioning right there could be some erratic behaviors.
-Steve
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The stepped pulley looks to be running true, the idler wheel is not. I would send the maker the video link and and ask for a refund.
To make sure that the o ring diameter is always running true?
I would super glue the o ring to its surface and chuck the whole thing in a lathe and grind down the OD so you know this area always runs true.
I haven't read the entire thread but can imagine someone has already done this?
Regards
David
I would super glue the o ring to its surface and chuck the whole thing in a lathe and grind down the OD so you know this area always runs true.
I haven't read the entire thread but can imagine someone has already done this?
Regards
David
Better to return idler than get someone to grind the OD
Many years ago I purchased an old Connoisseur transcription deck and built an arm for it from a HIFI magazine plan. I resurfaced the idler wheel, built a plinth and expected great things, but no such luck, I could not remove the rumble. It was more the subsonic rumble that made the speaker cones flap around like crazy, wasting all those watts.
Several years later I purchased a 124/II that required the arm rewiring and on inspection I noticed the deck had an idler wheel. Well, that was it, I felt there was a possibility I could be wasting my time again, so the project was shelved.
The Garrard 501 has a weighted rumble of - 78 dB and uses idler drive. It can be done. If someone owns a clock makers lathe or Unimat it is possible to true an idler if only the profile is out of true. A larger lathe can be used if it clocks up OK. One person I talked with had a contra-rotating grindstone with correct profile to do the job. Another used dry ice from the Walls ice cream factory to make the wheel solid so as to machine easilly.
The big puzzle with TD124 is it looks like they didn't have faith in pure idler drive and opted to belt decouple it. I was always surprised by this as the rumble figures are not as good as one would hope. In testing the passive filter unit I looked again at the motor. It seems the passive filter is a good idea and a fraction of the price of a regenerator type supply. If the idler is below spec none of it matters.
http://www.schopper.ch/uploads/imag...Restauration/Thorens TD 124 - step pulley.pdf
The big puzzle with TD124 is it looks like they didn't have faith in pure idler drive and opted to belt decouple it. I was always surprised by this as the rumble figures are not as good as one would hope. In testing the passive filter unit I looked again at the motor. It seems the passive filter is a good idea and a fraction of the price of a regenerator type supply. If the idler is below spec none of it matters.
http://www.schopper.ch/uploads/imag...Restauration/Thorens TD 124 - step pulley.pdf
I have three belt drives. A TD 160, a TD 125 custom long base, and an Empire 208. Each restored by me and placed in custom cherry plinths made by me. They are all quieter than the my TD 124. The little bit of noise my TD 124 makes barely makes a dent in the amazing quality of the sound. I'm trying to make it quieter because I think I can, and it's not like I don't have something nice to listen to while I'm working on it.
Thanks for all the suggestions. Still working on it here.
I've worked at seating the o-ring better, which has reduced both the noise and the wobble of the idler. Apparently the improperly seated o-ring (as can be seen in the video) resulted in the load to the idler changing as it spun, slightly displacing the idler. There is still a slight wobble to the o-ring which I suspect will go away over time, but it's far less than what it was and the idler itself no longer appears to wobble.
I've worked at seating the o-ring better, which has reduced both the noise and the wobble of the idler. Apparently the improperly seated o-ring (as can be seen in the video) resulted in the load to the idler changing as it spun, slightly displacing the idler. There is still a slight wobble to the o-ring which I suspect will go away over time, but it's far less than what it was and the idler itself no longer appears to wobble.
One sound I can hear even on good examples of TD124 is what sounds like a HF resonance coupled with a sound that is like a small metal object meeting the platter. This is mostly cured by using a cork platter mat. I suspect the sound is the idler making contact and the solid platter type ( unlike TD150 etc and LP12, the choosen masses cancel bell resonance ). The Garrard 401 is less prone to this which could be it's platter shape. Garrard did try machining out the platter edge to insert rubber. O-rings do the same job ( 11 x 1/4 inch x 2 in the strobe markings).
The Lenco is less prone despite other problems. The motor is a work of art.
The Lenco is less prone despite other problems. The motor is a work of art.
Luckily I did not ditch the 124/II, it is on shelf in the basement and for some reason has really gained in value?
Having served an apprenticeship as a scientific instrument maker, I enjoyed record players for their precision rather than for their performance
I also have a collection of decks in my redundancy corner, a 125 MKII with an SME arm, an Ariston RDII with an SME arm and a Technics SL110A with an Mayware Formula 4
I'm very happy with digital files now, I do not have the patience for vinyl.
I would get that idler wheel sorted, it runs out of true badly.
I request to see a video of the second idler wheel running against the stepped pulley. If the other wheel runs true, the problem is isolated to one bad wheel. If the other wheel exhibits the same behavior as the first, the problem is not isolated.
Still wondered how they measured this -78 db no info about the measurement setup. Concerning the Schopper measure rapport the 22 hz is the running motor freq. the ,,steppulley bearing noise I measured acts at about the 450 hz .
http://www.garrard501.com/aud1005_p0120_Garrard501.pdf
This is a translation by my friend Julian who had just learnt German so forgive errors.
http://www.garrard501.com/501 review En 10.05.pdf
All I know is, it was the best lab I ever saw. The original 501 was about 10 db less. A well set up 401 can do about - 60 db which I guess is about like the TD124 when ideal.
My feeling is the TD124 has much more to offer ( it has too ). If I used one at home I would try floating the turntable unit on squash balls and couple the motor to the base board. It would need constant adjustment no doubt. I suspect TD124 should top - 70db given a chance.
This is a translation by my friend Julian who had just learnt German so forgive errors.
http://www.garrard501.com/501 review En 10.05.pdf
All I know is, it was the best lab I ever saw. The original 501 was about 10 db less. A well set up 401 can do about - 60 db which I guess is about like the TD124 when ideal.
My feeling is the TD124 has much more to offer ( it has too ). If I used one at home I would try floating the turntable unit on squash balls and couple the motor to the base board. It would need constant adjustment no doubt. I suspect TD124 should top - 70db given a chance.
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