CED VideoDisc and Player Discussion

[Galgo]

Hi everyone.

I've recently gotten into the CED scene and I managed to snag myself an SFT100. I decided to mod in a composite + audio output by following the instructions in the CEDMagic FAQ:

"A/V output jacks can be added to the RCA SFT100... The audio and composite video test points are, respectively, TP3601 and TP3409 on the F, G, and Zenith players, and TP3504 and TP3410 on the J and K players. On the actual circuit boards inside the players, these test points are labeled TP601, TP409, TP04, and TP10, since it is standard practice to drop identical leading digits when labeling a related section of circuit board. After installation, it may be necessary to adjust the screw on the video level resistor R3202 to get a balanced image, and the original RF and added A/V outputs should not be used simultaneously."

The mod did indeed work, but I cannot for the life of me get a decently saturated image, and the blacks appear very washed out. What should be black is grey, what should be a vibrant red is a dull pink, etc. Adjusting the R3202 resistor made very little difference, and none of the other potentiometers managed to fix the picture 100%. Also the audio out is exceptionally noisy and quiet and sounds like a badly worn vinyl record. RF is indeed more saturated and has darker blacks and the audio is bearable, but it's rather inconvenient to use and the picture tends to be more warbly.

I was wondering if anyone had any advice on the matter? I have attached a picture of my board, as well as the schematic sticker on the case. Also attached are two video comparisons:

https://youtu.be/tSha6nKnxiA
Compares the modded composite output to the original RF. Audio is from RF.

https://youtu.be/EmtnjBg1-Bg
Compares the modded composite output to a VCR of similar vintage playing a VHS copy of the film. Left speaker audio is from the CED player, right the VCR.

Schematic: https://ibb.co/QHpmCvM

Circuit board: https://ibb.co/ZLq0Ybz
I have only tried adjusting the small plastic clear and colored pots, not the metal ones (are those even pots?)

Any help would be appreciated!!!

[Galgo]

So I added a 75 ohm resistor to the composite lead and now the picture is better, but the audio is still pretty bad. I saw a youtube video recommending the use of filter caps, what are they used for?

Before and after resistor comparison:
https://youtu.be/2qV0_jUsW2g

[Galgo]

I found an article called "Servicing video discs" and it goes into a lot of trouble shooting detail, I'll try some of its suggestions tomorrow when I have some time. It's pretty extensive so I thought it might be worth sharing: https://www.americanradiohistory.com/Archive-Radio-Electronics/80s/1985/Radio_Electronics_April_1985.CV01.pdf

Ctrl-f "videodisc" to find the section.

[jsdspif]

I hate to say it/ask it but it played ok originally? Then to the say it part, I'd leave the cover off this player and use it as a unit to just check your discs before playing. I have a 100 I use for that purpose and it's pretty nice to have.Then just buy a stereo player like a sgt200 would probably be the cheapest or a 250 becuase it has remote capable. That's what I and some other people here seem to like alot.

[Galgo]

Well I don't know what happened, but now the audio is popping like crazy and sounds like something is wrong. Does that sound like it could be a problem with the stylus? Video plays just fine.

And Jsdspif, I'll look into that, I've been meaning to get a stereo + composite out capable unit.

[SelectaVision420]

have you ever visually spot checked your discs before watching them? typically i only do this with a disc i havent watched in a player yet. the stylus could be dirty sure. but also these players develop issues with the tone arm after excessive use. and sometimes require a replacement of the whole tone arm.
_________________
(2)Sears 274 & 934(80150,10&11350), sft100, sgt250, sjt 090-400, vp550, VDR3000, VP2000 & 4000
complete '84 Dimensia Owner

[Galgo]

[Galgo]

Well I swapped the video and audio FM demodulators since they're actually identical chips and... no dice. The picture is still working flawlessly and the audio is still crackling like crazy.

At this point I'm out of ideas, does anyone know what might be the matter?

[SelectaVision420]

the tone arm itself may be to blame. its not uncommon to have to replace one.
_________________
(2)Sears 274 & 934(80150,10&11350), sft100, sgt250, sjt 090-400, vp550, VDR3000, VP2000 & 4000
complete '84 Dimensia Owner

[jsdspif]

I'm not sure how to word it,but what a stylus may or may not cause will never surprise me. I've had various problems and often thought "can't be the stylus". Switch it out with a KNOWN good one and problem is fixed. Send in the cart I just removed and report comes back "such and such wrong". In my opinion to work on them not knowing the condition of the stylus and better yet,having a known good one only used for testing along with a known good disc,is just a waste of time. I would just send in the cart,get an official report,make sure the disc isn't damaged (since video is playing fine I'm guessing there's no damage? I don't know if it's possible for a disc to have damage only to the audio only??) and then start testing again when you get the cart back. If anything the stylus will be cleaned and inspected,free of charge and you have good state of mind at that point as to whether or not there are stylus problems.

[Galgo]

Thanks for your response, jsdspif, it got me thinking though: can a bad stylus actually DAMAGE a disc??

[SelectaVision420]