CED VideoDisc and Player Discussion

[misternuvistor]

Hello everyone,

I am having some odd audio issues with my SJT200, it seems like the audio of a disc will play ok for a few minutes, but then the audio gradually starts to get noisy & distorted, and then it gets worse by pulsing in and out (almost in time with the disc's rotation, I'd hazard to guess). Eventually it'll just degrade to just popping noises and nothing else. And the strange thing is that the video is completely unaffected when all of this happens.

This problem first came up when I paused the disc for about 5 minutes when I had to step out of the room for a bathroom break. When I resumed playback, the audio was just the popping noises I mentioned earlier, but perfect video. I then ejected the disc and played a different disc, but the problem still existed. I did find out that I could temporarily clear the problem by powering down the player, then turning it back on again. That would initially help, but then the problem would come back again after 4-5 minutes of playback.

I'm a bit peeved that this is happening, since the I bought this player in restored condition from an eBay seller only about +-4 years ago, who claimed to had fully restored it, and it worked a treat until now (plus I've only lightly used the player since I received it). I'm wondering if there's possibly a bad capacitor in the audio stage, since the problem only seems to happen after the player is powered up and running for about 5 or so minutes, and temporarily goes away when power-cycled. Any suggestions?

Thanks,
Ryan

[Rixrex]

Well, as one who has restored these players, you can't really fault the restorer that much because of non-existent electonics issues that show up four or more years later. A restoration of a CED player could not possibly include all new circuit boards and electonics components, since they are not available, nor would anyone reasonably be expected to replace perfectly working components.

That being said, you are on the right track with what you suspect. The issue has to do with a component that is becoming gradually inoperative while in use. This typically indicates a component that's good when cool and no good when warmed up. The only way to know which one for sure is with testng. If you cannot test yourself, then you need to go to an electronics tech who can. The circuit diagram should be glued to the inside of the case.

Alternately, you get another player that might need some mechanical parts to operate properly and use your player for parts.

[misternuvistor]

[Rixrex]

I would say that the most common situation is for a resistor to change its values with age, especialy if subject to heating effects caused by current flow. This may eventually result in a transistor operating outside its normal parameters, for example running at a higher than permitted temperature. The reliability of any component is proportional to the power it dissipates meaning that if it normally gets hot it normally fails. Such reasoning means that a failed transistor is more likely to be in the output stages of a circuit, so that could be it.

Not sure how much the SKT 090 will help you with its design differences and non-stereo circuitry, but I'm sure some of us may have some parts players around that could help.

[kitchensynch]

[quote="misternuvistor]Yes, and I do have access to an ESR meter at work that I can use to at least test the caps in the audio section, since caps are usually the first to go. Now would a failing cap misbehave when warming up, or would that be more of an anomaly of an active component, like a bad transistor?

I'm glad RCA was thoughtful enough to have schematics listed on the player's inside (I'll have to pop open my player and check if it has it). Plus I have an old SKT090 I could use for parts if need be. Looks like another electronic project on my list, along with a SGT200 and Toshiba VP100 both in need of drive belts .

Thanks,
Ryan[/quote]

I would think that a bad output is going to act up whether it's cold or warm. Even if you don't see any obviously terminal caps I'll bet you will find a few resistors that are not happy ahead of the output.
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[Daxi Don]

[-Try the following to isolate the audio problem to a specific area of the stereo circuit. Play a dual audio channel disc. Jane Fonda's Workout disc is an example. Listen to both right and left channel outputs from the player. When the audio problems start toggle the player front panel buttons between audio A and then audio B. Does the problem happen on both channels or one or the other ?
Audio A information is on the L+R processor. This circuit is almost identical to an SJT mono player. The Audio B is on the L-R processing.

The most likely cause for audio problem is a bad Integrated Circuit. But you will need to investigate the circuit to find out which one.

CEDatum stocks all the [u]original RCA IC's [/u]for this player. All OEM.

[Beetlescott]

I'm sorry you are having problems with your player. This is prolly a moot question, but have you tried another disc? Sometimes you can get a disc that has issues. Also, someone chime in here if i'm wrong, but my SGT-200 & SGT-250 has a switch in the back A, B & Norm. Check and see if the "J" series has this and make sure everything is where it should be. Also check to make sure your wires are all plugged up tightly. I realize you have prolly already done all these things, but it never hurts to check. Might be a good idea to rule out the stylus too, if you have a spare. Good Luck!
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