RCA RP-217/218

[hermitcrab]

This changer is in my 3VF series hutch console... sounds great , except the changer runs fast on all speeds about 2 or 3 rpm fast , annoying especially when you know the music being played sounds wrong. I know there is nothing can be done on a shaded pole motor except play with the idlers... this has the original and it is very pliable. I wonder if sanding the idler down a couple mm would solve it? some people believe changing the idler size does nothing, but saying if you change a 2" idler with a 1" idler the speed will stay the same is laughable

[TC Chris]

Changing the idler diameter will not affect speed. Speed depends entirely on the driving and driven device diameters. That ratio is not affected by the idler.

In one rotation, the motor spindle or turret will cause the idler to advance by one circumference of the turret. The idler will then advance the platter by the same distance. A 1" idler will rotate faster, but still its outside edge will advance only by one turret diameter, and that's all the platter is going to advance.

Instead of ruining a functional idler, why not try making one of thin plywood or Masonite with a hole saw. Use a rubber band for a tire. See if you don't end up with about the same speed.

I have an old Garrard RC-80 that runs fast. My guess is that it's a European model intended for 50-cycle AC. I'll bet they used different diameters on the motor shaft sheave for US and European service.

Chris Campbell

[stbasil]

Hermitcrab, maybe the idler is not centered on the spindle speed step, say it's partially overhanging to the next higher speed, that can cause it to run a little fast, in my limited experience.

I know that the idler diameter isn't supposed to make a difference, and I understand the reason for that, but the last time I sanded one, just enough to take off the glaze, I noticed the speed went up by a small percentage. But maybe that was caused by some other side effect...

[TC Chris]

The reason for taking off the glaze is so it doesn't slip. That would explain the speed change.

Chris Campbell

[Hi-Fi-Mogul]

I would add to make sure there is no rubber
accumulation on the stepped spindle rotor of the
motor.

I encountered an increase in speed in that situation
on a standard Alliance motor in a V-M changer.

[Conelrad]

Idler gears in any gear train replicate the same motion speed in any application, regardless of diameter, as noted above.

Many years of broadcast turntable maintenance (and they always needed it, long hours of continuous use) for Rek-O-Kut, QRK, and Gates units used the same system, a rubberized puck rotating between the motor spindle and the inner lip under the platter for drive.

Clean the inner platter of any residue using Xylene, same for the spindle. Use 100-grit sandpaper to take off a very small amount of the idler running surface. I used a nut & bolt to sub for the shaft, turning it with a electric drill so as to get an even surface when finished. Just took seconds, really.

Reassemble & lube things, maybe change out a crappy platter felt if needed, job done.

If it was your average rocker cramming all the 'revenue time' (commercials), put a new wrap of a few turns of Scotch tape on the 45 part of the spindle to make those 45's play a bit faster. Program directors & managers loved that trick. The listeners never seemed to know...

D

[TC Chris]

Now you've got me wondering if Wurlitzer used that trick in my jukebox....

Chris Campbell