Thorens TD166MKII speed issue

[MuseChaser]

Well, at least I know I'm not going crazy. I was just listening to and enjoying Beethoven's Sonata No. 1, Op.12 in D for violin and piano, Isaac Stern and Eugene Istomin, on CBS Masterworks I2M 39680... and yet it just didn't sound like it was in D... and I KNOW that sonata.. I've played it on violin... I've played it on piano... I have "perfect pitch" in the sense that I know what a note is when I hear it, although I may not be able to tell you if it's EXACTLY A440 or A441, depending upon the day, humidity, blah blah blah. This just sounded in the cracks to me, and I don't know why I haven't noticed it recently. Thought I was going nuts, so I checked it with a tuner. It was definitely in the "cracks".. not quite D, not quite Eb...

No strobe, so I grabbed a stopwatch and timed 33 1/3 revolutions.... 58.6 seconds the first time, 59.2 the second time by eyeball. Yep... she's running fast! Did the math (60/59=1.017, then 440*1.017=447.5), calibrated a tuner reference to A447, and yep... that's closer to what I was hearing, but sounded even higher than that.. maybe A450.

Regardless.. my turntable is definitely too fast. I found another thread here that mentioned getting a new belt to correct it, but I'm having a tough time following that logic. First, I bought this table new, and it's the original belt. I know.. REALLY old, and it takes a LONG time for this turntable to come up to speed or stop, as the belt is pretty stretched out, but if anything that should might make it slip and run slow. Wear on the drive pulley would reduce it's diameter... ALSO contributing to a slower speed.

What's going on?!? Is there any adjustment I can make that will get the table back to the correct speed? It's powered by a wall wart adapter; does line voltage influence motor speed?

Here's two pics, if they are of any use solving the riddle. The pic of the drive pulley with the belt has an arrow indicating what looks like a small ring of felt at the bottom of the pulley. I can't tell if that's what it is, or if it's crud. Does anyone know?

Thanks in advance for any clues, tips, help, etc.

 

[mdc701]

You can download a speed test app like Turntabulator to more or less see how fast your turntable is going. Next step is to clean the pulley (yours look really dirty) with isopropyl alcohol and some cotton buds. Clean the inner platter as well. And finally yes, a new Thorens belt should more or less improve your speed accuracy.

Did I get it right that you got the table brand new and haven’t replaced the belt yet? Check out Vinyl Nirvana for some Thorens belts.

 

[MuseChaser]

Thanks for the reply...I've downloaded an app and will see if that corresponds with my eyeball/stopwatch calcs, and will clean as you suggested. Still trying to figure how a stretched out belt could increase the speed, but anything is worth trying. Anyone have any input re/ line voltage and speed in this 'table?

 

[Blue Shadow]

The belt should ride on the middle hump of that section of the pulley for correct speed when using a correct Thorens belt. You can adjust the position of the belt by adjusting the azimuth of the motor shaft as explained in the service manual avail on vinylengine.

Thorens TD166 2-Speed Belt-Drive Suspended Chassis Turntable Manual | Vinyl Engine

I looked at my 160 Super and the belt rides the ridge correctly. The SM for the 160 addressed the motor shaft azimuth.

 

[MuseChaser]

Thanks, Blue Shadow. I had found that link/site earlier and tried to download the manual, but I couldn't register for an account....kept getting the message "Sorry, but registration is currently closed to new members." Any ideas?

 

[mdc701]

Thanks, Blue Shadow. I had found that link/site earlier and tried to download the manual, but I couldn't register for an account....kept getting the message "Sorry, but registration is currently closed to new members." Any ideas?

PM me your email and I’ll send the pdf file to you. Btw Blue Shadow is right, the belt should ride a bit higher on your pulley. I didn’t notice your first picture.

 

[lini]

(...) does line voltage influence motor speed? (...)

It shouldn't (*) - as the motor is a synchronous type, so that only the mains frequency (or respectively the AC output frequency of a power supply with mains-independent frequency generation) should determine its speed.

Does anyone know?

Well, it's a belt-friendly slip clutch. I.e., there a two felt rings, one directly on the motor spindle (that's the one, you've spotted) and another at the bottom of the brass part at the top of the pulley assembly - and between those two run the two plastic parts of the pulley assembly, which are expanded by a spring inside and thus pressed against the two felt rings.

And yup, looks like your belt has streched enough to not run, where it should run, anymore.

Greetings from Munich!

Manfred / lini

*) Within reasonable limits, of course.

 

[MuseChaser]

Thanks everyone for all the help. The eagle-eyes that spotted the belt riding on the wrong part of the pulley surface were correct.... that was the problem.

I found an app that would measure the turntable RPM as well as any percentage of variation.... VERY neat. Had no idea such a thing existed. The app showed pretty much what I had calculated earlier, but it was a LOT faster and more accurate. Thanks for THAT tip.... fast speed verified.

I forced the belt to ride on the correct part of the pulley by placing a small cardboard shim underneath the metal arm that forces the belt onto the appropriate surface for 45 or 33 1/3 rpm. That cured the speed issue, and it measured pretty much dead on at that point. AND... more importantly, Beethoven's Sonata No. 1 for Violin and Piano in D Major was.... NOW IN D MAJOR!!! ....and the peasants rejoiced.....

OK.. next... identified the problem...soo... what caused it?

Time for this week's episode of "Stupid Confessions."

For decades, I've had this turntable perched atop a set of Audio Technica adjustable damping pucks. They came as a set of four when I bought them way back when, hoping they'd help with a springy floor problem in a house I was renting at the time (Nope.. not at all). My brilliant mind figured that a triangle of three would be more stable than four, and easier to level, so I only used three of them, and placed them directly on the bottom of the turntable instead of on three of the four corner feet (which would hae been very UNstable). It worked very well. What, it turns out, DIDN'T work very well over the years was that thin piece of ersatz engineered wood-like thin cardboardy stuff that covers the bottom of the table. It had warped under the weight of the table pushing down on the three AT pucks, and the internal springs were no longer able to let the platter sub-assembly drop far enough for that pulley to be at the right height. I never noticed it because every time I picked up the heavy platter to see what was wrong, the sub assembly WAS suspended without the weight of the platter.

Sooo.. the whole thing was my fault. I'm back to using all four pucks, and all is well. I may fabricate a new bottom cover from 1/4" hardwood ply; I still like the idea of three points of contact rather than four, especially for ease of leveling. Then again... it's not like I'm planning on moving the table around much.

Solved.... and thank you!

edit: - Oh... and the belt. Yes, it's original, and yes, there's not a lot of stretch to it, but it's working fine and the new one from Nirvana is... $30?!?!?!!!!! Good to know they have one, but as long as this one's working, I think I'll buy another couple albums instead.

 

[gadget73]

swap the bottom for a thicker one. That was one of the TD-160 Super modifications. The 166 is a kissing cousin to the 160, so I don't see why it wouldn't work there too. the stock 160 bottom panel is that thin pressboard junk. Mine is now sitting on a piece of 3/4 MDF. Not going to say it makes any sort of obvious difference in sound, but the original one was warped and the little teeny corner feet were junk. Now its got a felt-wrapped heavy board that can support nicer feet if I feel the need, or currently its just sitting on top of the shelf.

 

[Blue Shadow]

Yes that 30 bucks is way to much of an investment since you might be able to find a sweet direct drive on the used market with a nice cartridge for the same amount.


Ok more seriously, that tt and hence your original belt is about 35 years old. You are telling us that the Investment of 2¢ a week for the life of the table is too much to pay to get the belt to ride properly without assistance and have the table spin up to speed properly without a push start? Like not changing the starter in the car and just parking on a hill so you can pop the clutch while rolling to get the car started.

 

[MuseChaser]

The belt is riding properly now, had nothing to do with the problem, and the table starts fine without needing a push. I'm saying that right now a new belt is not necessary, and yes, that if it were, $30 is a pretty stiff price. When it becomes a necessity and if it's truly the best belt for the 'table, I'll still buy it.

 

[kbwhaaland]

Your piano recordings will probably sound better with a new belt.