CED VideoDisc and Player Discussion

[rferrara]

Sorry to ask, if this has already been addressed, but I can't seem to find the answer for this problem via search. I have a SGT-250 that has pretty bad snow in both the baseband video and RF outputs. The snow gets worse as the CED plays. After about 1/2 the disk the picture becomes totally blotched out and the sound disappears. All CED discs perform the same. Has anyone heard of this problem or knows a solution?

Thanks,
Ralph

[Sceptre]

Hi, ralph

I have a similar prob-mine shows mottled colours all over the screen.
In a couple of discs I can even see an RCA logo in the background, vaguely.

Sorry I cannot help-I need some answers on this myself.

Sceptre

[RT9342]

Have you tried a different stylus? The problems you are having sound like how my player played when the stylus got REALLY dirty, and I've noticed that some worn-out styli seem to always have a little bit of the picture problems you are talking about, until a better stylus is installed. I've never seen one so worn out that it would just have that poor of a picture all the time, but I'm guessing they can get that bad. If not, perhaps you may want to clean the brass contact in the tonearm and the stylus, which mate to carry the RF signal from the stylus into the tonearm. Also, make sure the little wire coming off the stylus tip to the brass contact is still intact. It's very fragile and I've seen them break before. I'd suspect a dirty disc too, but if you have a bunch of discs and they all look the same, then it's probably not the disc. If none of the above help.....I don't know what to tell you.....you may have a problem in the tonearm. RCA put labels on the tonearms saying they're not serviceable, but I've successfully done service on them, to improve tracking performance, but I've never tried to fix other problems on the tonearms.

[Sceptre]

Thank you very much RTM-I've posted this before-but you appear to be the first to answer me...I will try as you suggest, and if it works will get back here. And yes, all my discs appear that way.

Thanks again,

Sceptre.

[RT9342]

Not a problem. Sorry I couldn't help sooner - I've viewed this website before, but never actually messed with the forum. I hope that my info may help find the problem. I'm not a total expert on these, and haven't actually worked on an SGT-250, but I've rebuilt 2 SFT-100s, an SGT-200, and a Zenith, all of which are identical inside, except that the SGT-200 had an additional stereo decoder board & LED stuffed in it. If I'm not mistaken, the SGT-250 is pretty much an SGT-200 with soft loading and a remote, so I imagine that fixing playback problems on this model wouldn't be any different than doing so on the other models I've worked on.

[Matlab]

This may sound like a very simple answer to a dirty stylus. Remove the stylus and touch the tip gently with scotch tape. We used this method in the RCA lab to kept the diamonds clean.

[RT9342]

Cool! I never thought of cleaning it like that. So that's how it was done in the RCA lab? I'll trust it then. I'm guessing the SGT-250 (the player in question in this discussion) has a removeable stylus cover like most of the earlier units, right?

[Sceptre]

"I'm guessing the SGT-250 (the player in question in this discussion) has a removeable stylus cover like most of the earlier units, right?"

Good guess-mine does.

I haven't had time to 'play' with it yet-Xmas is 'pouring' down on me!

Gotta get a new comp.-this one is a 'loaner' and mine got trashed by our last storm...!

And this one won't recognize my scanner, nor my colour printer, nor my vidcam. Its floppy drive don't work either.

It's good for email though...

[rferrara]

Thanks to all who offered suggestions. I've cleaned the stylus and all the contact areas on the stylus and tone arm. I've even used the Sarnoff Labs technique, since I remembered it from when I was a RCA Labs employee for five years during the CED hayday. Unfortunately, I was in the automotive group and didn't get to learn the tricks of the CED people.

Does anyone know if there are any adjustments that would render a clearer picture, for example, What does the servo balance pot do? The fact that all disks start off playing snowy, but discernable but then towards the middle of the disk, they all become botchy, lose audio and finally drop video leads me to believe its a tracking problem and not just simply dirt. Is there a speed control adjustment that perhaps is not working properly? Is the speed of the disk supposed to vary as the stylus tracks inward to compensate for the ever shrinking track diameter? If so, is this on a servo also?

Once again thanks to any and all responders.
Ralph

[RT9342]

Well...first of all, unless it's also skipping real bad, I'd leave the servo balance alone - if you adjust it, your player will probably act like it's rewinding or fast-forwarding during normal play, or if it's a little off, rewind will be slower (or faster) than fast-forward. I don't have my player with me right now, but there may or may not be an adjustment to adjust the incoming RF level. Most of the adjustments, though, change the detail, or the clarity of the picture due to the color carrier, but I don't think these would help your player. I'll check mine tonight to see if I can figure out any other possibilities - I have it taken apart because it has a problem similar to yours, only with the audio instead of the video (the picture looks fine, but the audio sounds like you're playing a piece of sandpaper, rather than a disc).

[RT9342]

Oh, and by the way, the speed of the disc always remains constant, and the tonearm motor remains pretty constant too, unlike CLV laserdiscs, CDs, and DVDs. So unless the picture looks psychedelic, or it starts skipping like crazy, you won't have to worry about that.

[RT9342]

Sorry...didn't find any adjustment that would adjust the amount of noise in the picture (or in the sound either). Maybe something's burned out. I'm suspecting mine has a bad audio IC - yours could possibly have a bad video IC somewhere. Unless...did you get all your discs from the same place? I have several discs that I bought as a lot recently that ALL have really snowy picture - I thought my player was going bad, but my other discs still play great. I got better results after gently brushing the discs with 91% pure alcohol while spinning on the turntable. I don't know what else to tell you if none of this helps...I'm running out of ideas.