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Thorens TD-165 oscilating platter on startup

andylsun

andylsun

Active Member
I recently installed a genuine Thorens belt onto my TD-165 to replace the old belt that was present when I bought it.

Now, on startup, the suspended chassis oscillates while the motor gets up to speed. There's clear movement in the platter and the tonearm of at least 3-5mm. It doesn't seem to be in one axis, and does settle down when normal speed is reached.

As I've not owned one before is this considered normal with a new belt, or a sign that my suspension is not set correctly. Or could it indicate a problem with the motor start capacitor. Spin up time is good taking about 7 seconds to get to 33rpm.

The bearing well has been cleaned and lubricated and the motor is very quiet. Nothing rubbing or catching.
 
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Sounds like suspension to me. If the balance of the outer platter + record + record mat + weight/clamp (if used) is off, then it is very possible that it would be causing that movement.

First thing I always say to someone when they have issues sounding similar to this, flip your outer platter upside down and put it back on your inner platter. Also put a record mat, record, and a weight/clamp if used on it. Doing this will allow you to see what exactly is going on underneath the outer platter and will cause the suspension level to be more sensitive, making it easier to see if it is correct/incorrect, as the center of gravity is higher.
 
yeah, I'm also thinking suspension. Is the platter even with the top of the deck all the way around? If its low on one side, thats a sure sign the springs need some tuning.

Oh, did you talc the belt and clean the pulley and the inner platter where it rides? It needs to be clean and with a bit of talc on the belt to allow it to slip. If its fetching up a bit on startup you may get that shudder.
 
The platter is level all around compared to the top of the deck and also is on a level surface. I didn't talc the belt, but did clean the pulley and inner platter with denatured alcohol prior to installation of the new belt. The belt isn't slipping, which could be the problem? Will find some talc.

Will also try with the outer platter upside down and see if I can determine which way the suspension is bouncing. I did this when fitting the belt to make sure that it worked at both 33 and 45 without touching the changer arm.

It looks like the motor is cogging (stuttering) the first couple of turns as it starts up. I think this is normal and perhaps the belt isn't giving enough, so it's coupling this cogging to the platter.
 
Could be. The motors on these are relatively feeble and need some slippage in order to run up to speed.
 
I just measured the platter to deck height. It appears the platter (and sub platter) is higher at the front than the back - about 3mm difference at the edge of the platter. I'll need to either lower the front or raise the back. Should the bottom of the subplatter be higher, level or lower than the top of the deck when loaded with platter + stock mat + record?
 
It does float with upward and downward movement where the platter currently sits. I'll drop the front tonight and see how it goes. I've looked at the analog dept pages and they are great, but don't specify a sub platter to deck height.
 
usually you'd want to tighten the springs, not lower them. Springs don't get longer over time, they compress. Get the platter too low and it will start banging off the safety post.
 
That's why I'm trying to find out the recommended platter height. The springs have plenty of travel left in both downwards and upwards direction at the moment, but the platter is slightly lower at the back.

The bottom of the outer platter is currently 9mm above the deck at the front and 7mm above the deck at the back. I'll plan to raise the back so that it's also at 9mm.

Edit: From the analog dept

"Correct platter height will be such that the platter is not so low as to rub against the motor pulley, or safety post (if installed), and not so high that the spring grommets in the sub-chassis make contact with the underside of the top plate. The sub-chassis must float freely and be level."
 
Don't worry about the measurement stuff they say. What you really need is a bubble level which will allow you to adjust the springs so that under ACTUAL record playing weight load everything is level. You listen to a record with the sub platter + outer platter + record weight + record + clamp/weight if used, therefore you must adjust the suspension with ALL of those in place because you must adjust it under ACTUAL/DESIRED conditions.

You want it all to be as level as possible, and you want the platter setup + everything else to have a bounce when you push it down with your finger, floating. You don't want to compress the springs so much that it is touching the top chassis and you don't want them so decompressed that the weight of the assembly presses the springs all the way to the bottom. A healthy bounce will allow you to press it down with your finger so it literally bounces without touching the top chassis or the bottom of the spring studs/grommets. You want this bounce to have as little horizontal movement as possible.

When you do this, FLIP the outer platter upside down (it will sit on the inner platter just fine) and put the rest of the stuff on top. This will raise the center of gravity making the suspension setting more sensitive allowing you to fine tune it more as well as allow you to see EXACTLY what is going on underneath the outer platter.
 
I think the slip/grip cycle of the belt getting up to speed is amplified by the wonky suspension. Level up the suspension and talc the belt and you should be golden.
 
gadget73 said:
Could be. The motors on these are relatively feeble and need some slippage in order to run up to speed.
Click to expand...

You should not have to talk the belt. The pulley has a clutch in it that is supposed to slip a bit on startup. I have never put talc on the belt on any of my Thorens tables. It sounds like the suspension needs adjustment. Here's how I do it:
Adjust the suspension so that it is even all around and has about 1/8" clearance to the top "stop" if you lift up the platter or base of the arm.
 
dunno about a clutch. Pretty sure my 160 does not have that. It looks like a plastic pulley molded over a brass insert where it goes onto the shaft of the motor.
 
dr*audio said:
You should not have to talk the belt. The pulley has a clutch in it that is supposed to slip a bit on startup. I have never put talc on the belt on any of my Thorens tables.
Click to expand...

Yea this is what I've been told by a few people in my area. On a genuine Thorens belt you don't need talc.
 
dr*audio said:
You should not have to talk the belt. The pulley has a clutch in it that is supposed to slip a bit on startup. I have never put talc on the belt on any of my Thorens tables. It sounds like the suspension needs adjustment. Here's how I do it:
Adjust the suspension so that it is even all around and has about 1/8" clearance to the top "stop" if you lift up the platter or base of the arm.
Click to expand...

There's no clutch on the 165, but I think there is on the 160. I'll level up the suspension and report back.
 
sftypost3d.jpg


Found on the web.
 
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