Thorens TD-124 idler wheel or Stepped pully height adjustment?

[Quadman74]

Hello I just got a MK 1 124 with the early version of the stepped pulley. I have been going over it and I notice that the idler wheel tends to ride a bit high on the stepped pulley. Right at the very top of the step. I checked under the idler and the only washer there is the thin teflon one, no others. I then lifted the step pulley and found no washer under it, it rides on the metal that the C clip attaches to holding the felt pad down.

Question is there a way to adjust the height of either pulley without adding or taking away washers?
I assume I have a missing washer under my step pulley, I doubt it was intended to ride on the metal, That could possibly solve my issue.

Pics attached of idler at 33 RPM and stepped pully landing pad with no washer.

 

[heyraz]

Look below deck under the stepped pulley. You can raise/lower the stepped pulley's shaft.

Edit: Your underside image is of the magnetic eddy brake, not the stepped pulley spindle. When adjusted properly, the stepped pulley will be supported by and spin on the ball bearing at the top of the shaft, not the thin Teflon washer between the stepped pulley and the turntable's deck.
The idler wheel's shaft can also be raised and lowered.

If you look at the TD-124 long enough, it all makes sense. I think the design is very straightforward.

 

[Quadman74]

When adjusted properly, the stepped pulley will be supported by and spin on the ball bearing at the top of the shaft,

Hmm, I didn't realize it rotated on the ball bearing at the top of the pulley, no wonder I didn't have a washer there. The photo I attached above was to show no washer. Here's my stepped pulley. I'll poke around there more today, Your right it is pretty straight forward, I still haven't looked closely enough to see how to lower the idler wheel. I have a big order going to Audio Silente today for most of the rebuild. I learned a lot reading your experiences hopefully I'll be able to get my motor aligned just fine and because of you I also ordered the sintered Bronze main bearing sleeves after reading about your binding Nylatron bushings. My current deck motor speed is 1620 range according to the optical Tach I have. The table holds 33.3 and 45 nicely as it is (according to the tac, the strobe says it is slow) and is pretty quiet considering its age.

 

[heyraz]

Let us know your progress.
How is the strobe getting a different reading than your tach?
Line frequency?

 

[Quadman74]

How is the strobe getting a different reading than your tach?

Good question. Replacement tach coming today as the light beam is wonky on this one but if held correctly over the reflective tape it reads ok. My UPS shows constant 60 hz line frequency, 118V right now. Resistor to strobe lamp reads 35.7K ohms on my fluke 87, in spec. we'll see how the new tach reads later today.

My stepped pulley shaft will not budge, it like frozen in there. I removed braking plate and the 2 screws below the chassis that lock the stepped pulley spindle. Frozen, it will not move. Confirmed that the spindle is a touch higher than the step pulley (to top bearing) so the pulley definitely does not ride on the metal base below, guess that's why there is no washer. I still do not see how to adjust the idler wheel height. It seems the speed change cam is ultimately responsible for the idler height and that does not appear to be adjustable. It will be awhile before my refurb parts show up, I am just tinkering now and looking at how things work.

 

[Quadman74]

I figured out the idler wheel adjustment with a tip from Simone. Pretty course but got it dialed in. Say what brand of optical tachometer did you buy? were you happy with it? I got replacement today and its light beam looks good but 20 seconds and it couldn't figure out TT speed it was showing 74-213 RPM, finally on second attempt it briefly showed 33.4-33.5 before it went crazy again.

 

[heyraz]

I bought two tachometers. One is laser only, I think it has a pistol grip. The other is a combination contact and non contact (laser) that has a lower profile so I can get a more direct beam and reflection from the motor's pulley. Sorry, I don't remember the brands, they were both from Amazon, less than $100 each. After I finished the TD124, I removed the batteries from both and put them in storage.

I think using a non contact laser on the spinning platter is going to be inaccurate because the reflecting surface doesn't come around that often (reducing the sample size). A contact tach with a rolling tire might be slightly more accurate, but I think friction from the rolling wheel will affect the results. I think a lower profile laser is the way to go.
When I was checking the motor spindle I didn't use the reflecting tape. I inverted the motor's pulley (large diameter up) and applied some black electrical tape to all but about 1/4" of the pulley's outer surface. The exposed area became the reflective surface for the laser. The results were accurate and repeatable. That's how I was able to rule out the motor from causing the slow speed issues. The motor always spun at the same rpm as long as the main platter wasn't spinning.

To check the platter speed with a laser tach, I would put a 45 rpm adapter on the spindle and apply a small piece of reflective tape to the edge. You'll get more samples that way. Better yet, center a roll of black electrical tape over the spindle with a slice of reflective tape on the edge. Make sure the laser hits the reflective surface at a right angle so tachometer can pick up the reflection. You should get enough samples to accurately read the speed.

Glad to read you figured out how to move the idler assembly up and down. It's been a few years since I serviced my TD-124 and it still runs like a champ. I think it's a well designed and built turntable.

Good luck, keep us posted.