CED VideoDisc and Player Discussion

[toasterking]

I have an RCA SKT400. When some discs are loaded, I can hear the disc "rubbing" as it spins at a speed inconsistent with the turntable platter speed for several seconds after the turntable has approached full rotation speed. It seems that there is not enough friction between the disc and the turntable, and the turntable spins up faster than the disc. It may take as long as 5 seconds or so for the disc's speed to stabilize after the turntable has reached full speed. In the meantime, I can hear the stylus being lifted 1 or 2 times, while the screen remains black, before the disc reaches the proper speed. When it does finally start playing, it is 45 seconds or more into the feature. I can seek backwards to 00:00 and play that part just fine, but it just bothers me that I have to do that manually.

The symptom seems specific to the disc, or in some cases specific to only one side of a disc. Some discs never exhibit this problem when played, but most of mine do. Could it be that the pad on the turntable is lacking in friction anyway as a result of wear? May the pad just need to be cleaned or replaced? Any suggestions for cleaning it?

Thank you

[Rixrex]

Sounds like you've got a good diagnosis of where to begin. CED discs have a protective coating of silicon 'oil' and some of that might have been transferred to the platter. Start out by cleaning the pad and platter first. Simply clean with isopropyl alcohol that will generally pick up any oils, residues, etc, and will not cause damage to plastic parts and such, like tougher types of cleaning solutions. Wipe with lint-free cloth, like a clean, old white T-shirt. Try that and see how things go.

[mnallard]

One of my granmother's player (SJT-100) had a similar problem. With the top off and watching it do its thing from a side view at eye level with the turntable. I noticed that the disc was actually NOT sitting on the turntable. Bravely, I removed the center hub and had to weaken the spring underneath it just a tad. This seemed to solve the problem. The cause of this I'm not sure.

The only logical theory I could think of was that either RCA had used a substitute spring or some of the discs were lighter than others.

If the other posted method doesn't work, you might try what I've suggested. Hope this helps...cause you have a player worth saving!

[toasterking]

I finally got around to playing with this. I tried the first method (cleaning the platter and pad) first, but it didn't work. I found that my player was exhibiting the same symptom that mnallard reported. With the spring completely removed and the hub reattached, it actually loaded, unloaded, and spun up and down perfectly. I was even questioning why RCA had put a spring there in the first place. Then I noticed the picture wobbling ever so slightly. It turns out that the combination of the spring-loaded movement of the hub and tapered shape at the bottom of it serve to help center the disc on the hub when it is loaded. It continues to amaze me with this format that the slightest change in physics causes such an obvious change in playback. It is nothing short of amazing to me that RCA ever made the players precise enough to work at all.

I first tried adjusting the turntable height, just to see if the hub height moved along with it -- it did, so this wasn't the problem. Mnallard's suggestion of weakening the spring worked beautifully (great job there!) but it still bothers me that I also can't figure out why. Springs are supposed to get weaker with use, not stronger! His theories seem as good as any.

Thanks!