Idler rumble?

[PatP]

Hi all, I've just bought a lovely looking 401 off eBay. It came with it's original box, instructions and even the inspection report and tag. The seller said that it had hardly been used and by the looks of it, I believe him.

However, there is a problem! When I switched it on I can clearly hear the chassis rumbling and the platter ringing a bit too. With the platter off, if I move the idler wheel away from the motor spindle the rumbling stops. The problem gets worse as the speed increases.

Looking at the wheel the outer edge appears to be running true but the inner metal hub is clearly spinning eccentrically as the bearing pin is not exactly centred.

Also, if I hold the edge of the wheel I can rock it a tiny bit.

So, before I go out and buy a new idler wheel and bearings is there anything else I should check first?

Sorry if this all been answered before, I did have a long look at previous posts last night, but any help would be very much appreciated.

[DSJR]

Not an uncommon thing... try to get the idler as clean as possible on the driven surface and also the inside of the platter. make sure all the fittings to the plinth are firmly tight and that everything that needs lubricating is lubricated

Good luck. There's loads of info regarding 401 fettling, but for now, I'd avoid expensive bearing tweaks, as the original was designed for basically 24/7 in a broadcast environment and is well up to decent domestic use

[PatP]

Thanks DSJR, I don't think I know enough about these turntables to diagnose the problem so I've sent it off to Dr Martin Bastin for a full service.

[flavio81]

Thanks DSJR, I don't think I know enough about these turntables to diagnose the problem so I've sent it off to Dr Martin Bastin for a full service.

You have an amazing turntable, there is a lot of info on the net concerning its innards. Try to get more acquainted with the mechanism, you will be rewarded with great sound.

[brownemi]

Hi I hope you loosened the motor transport screws (red ones) to let the motor hang properly. This can cause all sorts of problems if not loosened.

[zebra100]

I have just solved a similar issue with a Garrard 82. I put a tiny ammount of light machine oil in the bearing of the idler wheel (don't get any on the rubber). Instantly quieter.