CED VideoDisc and Player Discussion

[TGM]

I heard its possible to mod an SJT-100 to have composite video. Are there any write-ups or guides on how I can do that? Or do I have to just directly rip the composite circuitry out of an AV system and transplant them part by part?
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Glitchy Mario

SJT-100 (not working )
Sears 934.54780150/CED-1 Frankenstein

[jsdspif]

seems like at one point in time there was discussion and I'd say it's possible,i believe there is audio and video that is fed into ,I don't know if my terminology is correct,a rf converter that turns the audio and vido into a channel 3 or channel 4 signal. A service manual may even have a test point where one would check to see if there is video output,to determine if the problem of no video (if that was an actual problem you were trying to fix) is within that rf converter or if there is a problem before the converter.

[TGM]

I was looking through the schematic and found the video out circuit, and it doesn't seem too difficult. It consists of some caps, resisters, an inductor, and a PN2907 transistor video buffer, all of which are still readily available today. If I just populate this area, I believe it should work. Would this work or am I missing something?


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Glitchy Mario

SJT-100 (not working )
Sears 934.54780150/CED-1 Frankenstein

[jsdspif]

is the video output circuit actually in the sjt100? because it states not used in sjt100? I would think maybe there is video at tp 3410?it looks like 3501 and 3502 would be where to check for your channel 3 and 4 output. I don't know enough about it and it's been a while but if you have the service manual and look for the trouble shooting section for "no video" or whatever it will probably say test for video at test point. The service manuals are helpful and there has been discussion about this before (I think?) but I'm going to say it was years ago,like more than 5 years? Hopefully someone will know for sure and chime in. I don't work on much stuff but I saw a service manual for a laserdisc player and I didn't find it very helpful compared to the ser. manuals for ced players, I've fixed up some players with the service manual and a little help here and there from john stephens.My problems were with the g series players. They were bad IC's in the audio portion so I replaced them.The replacements john sent said the chips in the g series were more prone to failure and the chips he had he called "more robust designed for the j series". For me I don't like the mono players and only the rf jack output. For me if I have to fix something I'd start with a stereo model. The problem is getting one to your house,if it has to be shipped to you is getting it without more damge being done to it.

[TGM]

[TGM]

Ladies and gentlemen... History has been made!


So why is the video washed out? I have a few ideas:
A. I used really long wire with no shielding
B. My work space is a half insulated garage and outside is currently -11 degrees, so it’s super cold.
C. Aliens
For now, think of this as a proof of concept, not as something you can do at this moment. I still want to confirm why the video is washed out not to mention I still need to find the audio TP. Ill try a dedicated AV cable tomorrow so hopefully it'll look good, even without the de-noise circuit
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Glitchy Mario

SJT-100 (not working )
Sears 934.54780150/CED-1 Frankenstein

[jsdspif]

i'd say get it somewhere normal room temp,i agree no shields on long wires you may be getting interference.Can you try to compare it's rf output to what you have now> I'm guessing your last post showing the tv is wires connected to a test point? I'm wondering if going thru the remainder of the rf portion of circuit does anything to improve quality because if it did have a rca out for video it would be going thru the circuit where there are no components,but of course it would have thos components if it had the rca out. I have -10 this morning in southwest michigan,i'm pretty sure that will be a record.I know about 10 years ago we had -6 or -8 and it seemed at that time it was coldest ever recorded for here.It's going to be like that all week.I have my thermostat on 69 and my furnace runs almost continuously.fortunately my house is small so doesn't cost alot to heat it but it's nervewracking to have it shut off only to start up 3 or 4 minutes later.I just had it all tuned up so hopefully I'm all set.

[TGM]

"IT WORKS! I FINALLY INVENTED SOMETHING THAT WORKS!"

The possibly first ever clean composite signal from an SJT-100! Its very noticeably smoother without that color-y static that RF has.

RF: (note the colored artifacting and interlacing)


AV: (there is a color banding pattern on screen, but it only shows up on camera. it doesn't exist when watching.)


Im not even sure if the de-noise circuit is really needed. It may make it just a little cleaner, but the picture is way cleaner than RF already. The total BOM should be around $20 USD, if anyone wants to try it. But now we know it's not only possible to make an AV out mod, but that its pretty easy too! I take this mod out of the proof of concept stage, and into R&D! Now I just need to find the audio TPs (Which I'm really struggling to find, if someone knows, please tell me.), Then I feel good about installing this permanently, which has its own set of complications, but lets not worry about that now.
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Glitchy Mario

SJT-100 (not working )
Sears 934.54780150/CED-1 Frankenstein

[TGM]

Found the TPs for the sound! (Left: TP4001/ Right: TP4002) They work great! Unfortunately the video is going wonky on my system now, probably because of the low temps in the garage or me not putting something back together quite right. But once I figure those out, and make the build permanent, I think It'll be a great mod the SJT-100's!
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Glitchy Mario

SJT-100 (not working )
Sears 934.54780150/CED-1 Frankenstein

[TGM]

I think I killed my player

The color was flickering for a few seconds, then the picture cut out entirely, and I can’t get it back with either RF or my composite mod. Besides that, the player seems just fine. I can still get audio from my mod, and the mechanics are working, (turntable was dragging, so I raised that, but no difference) so I know its something in the video circuit. I’m gonna keep looking, but dang it, it was my only working player. I dont know what even happened, the cables didn’t short or anything. If anyone knows what I can look for, please respond to the thread.
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Glitchy Mario

SJT-100 (not working )
Sears 934.54780150/CED-1 Frankenstein

[TGM]

I have a new(?) discovery.

I have seen CED Magic and cedatum make references to an adapter board or kit made ~2006 for some players RF only auto load Players:

tip #7: https://cedatum.com/service-tips-timesavers/
(and one other forum link I cant find anymore. Will update if I find it, but I believe it was by CEDMagic, and describes a board adapter installed inside the player to have AV out capabilities)

and a page that describes the test points for all non AV players
https://www.cedmagic.com/home/cedfaq.html#twofifteen

So there apparently was a board design made to add AV to these players, but because production PCBs went as accessible as they are now, I don't know if any were made. If possible, id like to see the design, since I've found that you cant use standard AV ports in the player since the spacing is too different between the board and the pre-cut holes.
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Glitchy Mario

SJT-100 (not working )
Sears 934.54780150/CED-1 Frankenstein

[jsdspif]

wish I would have seen that troubleshooting deal by John years ago.never seen that before but I see it would have been very helpful

[TGM]

After some more investigation, I’ve found that the cable I used to wire in the composite output accidentally got shorted, and that’s likely why my player died. Until I get new parts, I have to repurpose a working audio decoder in my player as a video decoder (they are both CA3215E chips), so this will be a mono player. Moral of this entire project: make sure things aren’t shorted.

On the topic of the mod itself, without an adapter PCB to align any board mounted ports, you need bolt mounted AV ports. The holes to screw the ports into are already there, but it’s covered up by a sticker that spans the entire bottom back case. The sticker has all the text telling what inputs are what, so you may need to make labels if you don’t know which are which without it.
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Glitchy Mario

SJT-100 (not working )
Sears 934.54780150/CED-1 Frankenstein