Spent a good amount of time online but can seem to troubleshoot this. I should note that this is my first Thorens TD124 mkII so I’ve never experienced one in top working order.
When I got the turntable the idler wheel seemed to have issues with engagement. I’ve since gone through a detailed cleaning as per the many resources online and while everything is running and functioning great, the idler wheel does not engage the platter. It just sort of flops around.
I understand that with the platter off it will not fully engage.
Out of curiosity, I put an extra turn on the idler linkage spring to pre load it. This made the idler engage and the platter spin but this should not be the fix. I worry that this is putting stress on all components in the chair and will induce rumble. Also it seems like the clutch can’t stop the platter in this state.
I’ve cleaned and lightly polished and lubed all linkage parts and there is no build up of old lube.
Any help would be appreciated!
When I got the turntable the idler wheel seemed to have issues with engagement. I’ve since gone through a detailed cleaning as per the many resources online and while everything is running and functioning great, the idler wheel does not engage the platter. It just sort of flops around.
I understand that with the platter off it will not fully engage.
Out of curiosity, I put an extra turn on the idler linkage spring to pre load it. This made the idler engage and the platter spin but this should not be the fix. I worry that this is putting stress on all components in the chair and will induce rumble. Also it seems like the clutch can’t stop the platter in this state.
I’ve cleaned and lightly polished and lubed all linkage parts and there is no build up of old lube.
Any help would be appreciated!
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I've restored 15 or 16 124s and haven't encountered this problem, so I don't believe it's common. But here's a few thoughts:
- the clutch doesn't stop the platter, it just lifts the aluminum top platter off the main iron platter
- if you haven't replaced the idler, it may be too hard/slick to engage properly. I recommend either Terry's Rollers (refurbishment) or AudioSilente (replacement)
- you are correct, the idler won't engage at all with platter removed - nothing to stop it from moving out and away from stepped pulley
- be sure the idler wheel is engaging the stepped pulley correctly - I've had them hit at the step and not stay in place (e.g. can move up/higher than the desired step)
- I'd check the movement of all the linkages to see what might be binding and keeping the idler from engaging completely. There are some adjustments if you think the idler is just not moving close enough to fully engage - won't take much
- clean the inner surface of the iron platter where the idler engages
@hirscwi thanks for the note!
to your points... when I preload the spring by giving it an extra turn to provide a little more tension, the turntable works fine. the idler wheel makes firm contact with the stepped pulley and is just the right height (1/64" above the step as per the service manual). ive thoroughly cleaned all surfaes on the inner platter, all pulleys and lightly resurfaced the idler wheel on the lathe. the linkage movement was cleaned and seems fine, it just appears that the spring doesn't have enough force to push it against the pulley and the idler wheel. perhaps it's as simple as the spring is worn out... i feel like this must be a rare condition.
to your points... when I preload the spring by giving it an extra turn to provide a little more tension, the turntable works fine. the idler wheel makes firm contact with the stepped pulley and is just the right height (1/64" above the step as per the service manual). ive thoroughly cleaned all surfaes on the inner platter, all pulleys and lightly resurfaced the idler wheel on the lathe. the linkage movement was cleaned and seems fine, it just appears that the spring doesn't have enough force to push it against the pulley and the idler wheel. perhaps it's as simple as the spring is worn out... i feel like this must be a rare condition.
If that solves it, I wouldn't worry about it. I don't believe the tension is critical. Once the idler touches the inside of the platter, the rotational force pulls it tighter against the stepped pulley and platter and the spring is no longer part of the process - i.e. only important at the start of engagement. The spring could have been stretched somewhere in the past or just failing.
@hirscwi the pre-load solved it. its running quietly and there doesn't seem to me too much pressure between the stepped pulley and idler wheel - something that might cause rumble or other noise. as you mentioned, perhaps the spring was stretched at some point... unsure but happy it's up and running.