Are they f***ing kidding??

[Jeffhs]

Originally Posted by RetroHacker

The drive motor drives the turntable by way of a very specific rubber wheel that would normally be unique to the model of phonograph.



-Ian

What is the difference between the idler wheels used with 78 phonos and the more modern ones? I would think an idler wheel is an idler wheel, regardless of how old or new the turntable is. Was there something special about the type of rubber used in those vintage idlers?

[RetroHacker]

What is the difference between the idler wheels used with 78 phonos and the more modern ones? I would think an idler wheel is an idler wheel, regardless of how old or new the turntable is. Was there something special about the type of rubber used in those vintage idlers?

It isn't a matter of the type of rubber, it's a matter of the size of the wheel. Inner diameter, outer diameter, and occasionally thickness will make a difference. The wheel has to be able to fit on the spindle provided, and also be able to properly drive the turntable, and be drivin by the motor. Also, due to certain laws of rotational physics, the size of the turntable relative to the size of the idler wheel and the speed of the motor will affect the (rather crucial) speed of the turntable itself.

I've personally not had any luck tracking down suitable replacement wheels for the turntables that I have. I've even tried making things, and modifying other idlers, but haven't had useable success. Replacing the pickup with something a little easier to find is rather simple. It's not that hard to fit a PowerPoint holder or a Tetrad pickup in one of the old arms. Adjusting the tracking force is usually just a matter or adding weight to the base of the arm. But I just have never been able to find a good way to replace the idler wheel. How much does it typically cost to have an idler retreaded? Where does one go for such a service? Have people had good luck with rebuilt idlers?

-Ian

[Chad Hauris]

The idler wheel size makes no difference in the speed when there is a 3-component system in a phono (motor shaft, idler wheel, turntable)...what does, are the diameter of the motor shaft and the inside diameter of the turntable. The idler just has to physically fit between the two...it is just a "go-between" and has no influence on the speed of the turntable.

We do a lot of work on 40's era phonos and find that new old stock Walsco, etc. replacement idler wheels in sealed packages still have their pliability...most idler wheels that have been exposed to the air for longer than 30 yrs or so get hardened and end up transmitting motor vibration to the record resulting in excessive hum. Have not tried re-built idler wheels.

We have been able to rejuvinate wheels that have dents in them from sitting against the motor shaft by chucking them up in the drill and using sandpaper to grind away the very outer edge, containing the distorted area...rubber rejuvinator can help on dried out wheels but it seems to be a temporary fix.

[RetroHacker]

Originally Posted by Chad Hauris

The idler wheel size makes no difference in the speed when there is a 3-component system in a phono (motor shaft, idler wheel, turntable)...what does, are the diameter of the motor shaft and the inside diameter of the turntable. The idler just has to physically fit between the two...it is just a "go-between" and has no influence on the speed of the turntable.

You're absolutely right - I totally forgot about that.. It's been a while since I tried to work on an idler drivin turntable. Thinking belt/pully here... OK, so it seems I have a lot to learn about this vintage phonograph - I guess I just never got too deep into trying to repair them - I'm more of a TV, Hi-Fi and computer guy myself. Bah - that's no excuse, I just need to shut up unless I'm more than 100% sure that what I have to say is useful.

-Ian

[David Roper]

http://cgi.ebay.com/1947-Silvertone-...QQcmdZViewItem

That's better.
[just ignore the BIN]