Turntable bounces at spin up

[Otto]

Hi there,

I have a problem with my vintage Thorens turntable. I recently replaced the drive belt with one from turntablebasics.com. The one I bought was listed as the appropriate replacement part, and appears to be the right size. In general, it works.

However, at spin up, the platter and tonearm, which are both mounted to the same under-assembly, bounce and undulate. This appears to be caused by the belt slipping, and then grabbing, and then slipping, and then grabbing -- you get the idea, it's kind of like when a teenager can't quite get the clutch right in a manual transmission car.

I didn't have this problem with the old belt, and I think it's because it was rather dry and therefore it did more of the slipping, and no so much of the grabbing, until it was fully up to speed.

Anyone know how to get rid of this? Is there a special turntable-belt-goo that I should apply. I can tell you that human saliva does not make a difference.

Thanks in advance for any advice!

[Mike P.]

You can try cleaning the platter and the drive motor head and see if that will make a difference.

[clubfoot]

Clean the drive pulley and platter belt surface, and use a little talc powder on the drive belt. I know what you're thinking,...it will slip more with the talc powder, but that's what my Systemdek manual says to do to "condition" the drive belt. Hope it helps.
Now saying that, if you have a low torque drive motor like mine and a heavy platter you will need to give the platter a little assistance on startup, otherwise there will be allot of belt slippage.

[Otto]

Hey guys,

Thanks for the tips. I cleaned everthing up and put some powder on the belt. No more bouncing!

Thanks!

[clubfoot]

You're welcome