CED VideoDisc and Player Discussion

[blindfury420]

So I was watching a movie on my skt-400 last night, finished the movie and put in a new one. All of a sudden (maybe i just didnt notice before idk) the screen starts to wobble left and right about a half inch or so each way slightly fast. So I take it out and try in my sft-100 and it plays amazingly, then back into skt-400 and its weeble wobble city Is it the turntable out of whack and an adjustment will fix? I've never seen this on any of my players and just not sure whats wrong.
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I dont own

McMicheal 5001h
Hitachi VIP202P
JCP 686-5705
RCA SKT265, SKT300
RCA SJT400X, SJT425

[deantjeep]

Open the player and watch the turntable spin when you play a disc. If the disc wobbles, then try another one, if each one you try wobbles, then you have an issue with the turntable. You can try to adjust the height adjustment under the player with a 1/16" allen wrench. If that doesn't provide any improvement, you may have an out of balance turntable. If the turntable is in fact out of balance, all you can do is replace the turntable. You could try swapping the turntable with one from a known good player. There is no repair for an out of balance turntable, you can only replace it with a known good one. Hope this helps you out.

[blindfury420]

Thank you for the quick response! I will be trying that later on tonight for sure! thanks
_________________
I dont own

McMicheal 5001h
Hitachi VIP202P
JCP 686-5705
RCA SKT265, SKT300
RCA SJT400X, SJT425

[Beetlescott]

You can use a turntable from an SJT300 on an SJT400, right?
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1000 titles
SGT-250
SJT-400
Montgomery Ward
SGT-100

[deantjeep]

I think any turntable from any of the SJT or SKT players are interchangeable. I understand from Tom that once the turntable goes out of balance it is usually the end of its life. If you examine the underside of a turntable, you might find some circular cutouts in the turntable plastic. You may see one or more of these. They seem to be about the size of a dime or nickel. I believe these cuts were made to remove weight from one side of the turntable and put the turntable in balance. I am not sure of what puts a turntable out of balance, other than the usual knocking around during shipping and maybe some warpage.

[deantjeep]

Hello everyone!

I received an email from John at CEDatum outlining more information about turntable wobble, please see below:

Hello Dean,

I would like to add a few comments on the subject of CED player turntable wobble.

On the J and K line players the TT's are interchangeable. It is very unlikely that a turntable would go out of balance in the middle of playing a disc. These TT's are rugged. The only problem CEDatum has had with the J/K TT is that the center spline breaks loose and will require glueing back into position, but this condition will not cause wobble but rather a mechanical noise as the TT rotates and touches the chassis.

All RCA CED players incorporate a 'timebase correction' system. The system minimizes timing errors that can cause picture wobble and chroma errors ( color changes in the picture). The timebase system incorporates two elements. Electronic correction for high frequency errors and a electro-mechanical system for low frequency errors.

A side to side wobble in the picture will be a low frequency error. The mechanical part of system is the armstretcher. This is a coil with a small plunger that is in contact with the metal plate on the back of the stylus. The armstretcher quickly moves the stylus tip position during play to compensate for timing errors due TT wobble or disc pressing excentricities.

RCA Service Company put out an RCA internal memo on armstretcher problems:

If the picture shows side to side movement:

A/ Look across the disc as it plays and observe the stylus tip. - the tip should be moving back and forward as the disc rotates. If the tip is not moving then the armstretcher may be faulty. A light finger touch on the center area of the disc while it rotates should produce a wide swing of the stylus tip.

B/ To check the armstretcher: Remove the stylus cartridge. With the player unplugged from AC power, check the resistance of the armstretcher coil. There are 2 wires, usually green and white. Is it open circuit ? A typical resistance is approx 100 ohms. If the resistance is above 140 ohms then the coil may be faultly and should be replaced.

John.

I need to add that John is a great guy, with exceptional services. Please contact John at cedatum@ccrtc.com for parts and stylii repair. Thanks John!!

[blindfury420]

That is an amazing amount of info dean, I appreciate you helping and posting that! I have talked to cedatum about sylus repair too! He is a cool helpful guy too!

I think I need to get a service manual or find someone who can teach repair, so I can make videos of the repair, so others can see it and do it if they have to. I still know way too little on repairing them.

In suggestion A Ive tried lookin at the stylus while it moves, I cant get any light down there to see it no matter what angle I try. I even have one of the bendable led scopes.

In suggestion B No offense at all, but w/o pics im really not sure what to do

Again I really do appreciate the effort you put in to helping me! You didnt have to ask cedatum or post the info, but you did, and for that I thank you!
_________________
I dont own

McMicheal 5001h
Hitachi VIP202P
JCP 686-5705
RCA SKT265, SKT300
RCA SJT400X, SJT425

[deantjeep]

Blindfury, email me and I can send you some PDF files that contain the service manual for the SJT line of players. This basically applies to the SKT models somewhat too. deantjeep@netscape.net

[toasterking]

Also, check that the disc is centered on the turntable. If the disc is not perfectly centered, the variation in distance as it spins may too great for the armstretcher to correct, and can result in a wobbly picture. On the J/K turntables, there is a black plastic shaft in the center of the turntable around which the disc's hub seats. It may appear cylindrical at first glance, but is actually somewhat conical/tapered. This shaft is spring-loaded and aids in the centering of the disc as it drops onto the turntable. If the spring is too weak or the shaft is stuck, the disc may not get centered properly. If the spring is too strong, the disc may not actually rest fully against the turntable and can have trouble spinning up or stopping.

[blindfury420]

thanks toaster! ill be checkin that too!
_________________
I dont own

McMicheal 5001h
Hitachi VIP202P
JCP 686-5705
RCA SKT265, SKT300
RCA SJT400X, SJT425