Trying to solve laserdisc video connection issue

Discussion in 'Home Theater Projects' started by Jon Bell, Oct 5, 2004.

  1. Jon Bell

    Jon Bell Stunt Coordinator

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    OK, here's the deal:

    When I ran the cables in the ceiling for my projector (Sanyo Z-2), I ran component, but didn't run S-video or composite. It comes time to hook up the laserdisc player (old Denon ebay special, don't know the model #), and it just has composite video.

    I've been making due by switching the green component cable from the green jack to the yellow video jack on the projector and in the back of the receiver (I'm doing video switching thru the receiver-- Pioneer VSX-812). This works, but is a bit of an inconvenience because I have to unplug stuff and realign the projector, etc. I watch LD maybe 5% of the time, so this is not a big dilemma.

    But, I'd like to find a more elegant solution that doesn't involve tearing the ceiling open and running new cables. An idea that I had was to attach a Y splitter to the receiver that would attach to the green component jack and the yellow composite (monitor out) jack and merge into the green component cable. At the projector, the green component cable would split and go to the green component jack and the yellow composite jack.

    The green component cable would get component signal only when the receiver was switched to HDTV or DVD, and composite signal only when the receiver was switched to LD.

    Does this sound like it would work?

    Does it sound safe? I don't want to fry anything on the projector.

    Do you think the signal would degrade? The quality of the laserdisc video is already pretty poor (and I'd love to find a way to improve it if anyone has any ideas).

    If you've gotten this far, thanks for reading.
     
  2. JasonGabler

    JasonGabler Auditioning

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    Hopefully you installed these cables in a free flowing manner. If so, you could tie 3 pieces of chord to the component cable and use it to the pull the chords through. Then use one chord to pull the component cable back into to place and another chord to pull a new composite cable through. The third chord you would leave in place for when you have to do this again [​IMG] No pulling the ceiling apart.

    (If all this chord stuff isn't possible...)

    You might very well get feedback if the video component not in use was not completely shut off... it might even need to be unplugged! Another possible problem is creating a ground-loop.

    Were I in your shoes, I'd pull a new cable... but I'm a newb [​IMG]

    jason
     
  3. Jon Bell

    Jon Bell Stunt Coordinator

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    Pulling another cable isn't an option-- it's not a straight shot throught the ceiling joists, and I did not have the ability to put conduit there (too many bends because of wires and HVAC).

    Could you elaborate on the feedback or ground loop comment?
     
  4. Allan Jayne

    Allan Jayne Cinematographer

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    Use the split and merge method you describe, but use switch boxes rather than Y connectors. Otherwise impedances will get messed up and you could have ghosts or picture quality loss. You will have to reach up with a stick to select the video connection at the projector, if the switch box is not remote controlled.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm

    Ground loop problems (typically showing up as lines drifting across the screen) may occur if some of the cable plug outer shells are oxidized, but any ground loop problem is just as likely to be there with the existing component video connections as with stringing a composite cable along the ceiling or sharing a cable.

    How is the de-interlacing in the projector. If not superb such as with a Faroudja DCDi chip, you might want to get an external de-interlacer to put next to the receiver for LD player and VCR and ordijnary broadcasts. Most of the popular ones output component video (the others ouput only RGB). An original iScan (about USD 200. on eBay) does a surprisingly good job except it does not zoom letterboxed LD pictures from pillarbox to near-full-16:9-screen.
     
  5. JasonGabler

    JasonGabler Auditioning

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    Ground loops are evil. Try to picture this. You have two outlets on the same circuit. You plug in two A/V devices, one to each outlet. Then you run an A/V connection (audio in/out, or video in/out) across the devices. Now you have a complete circle/circiut/loop for a ground to run across: outlet to power cable to device to A/V cable to device to power cable to outlet to house wiring back to the originating outlet. It causes all sorts of problems. It gets trickier to solve when the connection across devices is more subtle, like when I found out that my digital cable line coming into the building wasn't grounded properly and it caused my projector to have problems and audio devices to hum like mad. Putting this Y splitter in could possibly generate such a problem - you're making more paths between systems than you need.

    The potential for feedback is pretty much related to the same issue - more paths than you need. In this case you have an foreign signal (say the green component) output sharing a line with the composite output If both outputs are hot there's no telling what this might produce. Let me give you one example: I was trying to figure an audio problem out one day and I inadvertantly put an audio output from my computer into an output on my A/V switch. I didn't realize that I had put it into an output instead of an input. After cranking multiple components I basically destroyed the switch... thank God that's all that was damaged. It wasn't just a passive, mechanical switcher and so I blew some circuitry on it. If you put in a dumb Y splitter that has no way to control signals from spilling between outputs, you could potentially cause signal problems and at worst fry something.


    jason
     
  6. Jon Bell

    Jon Bell Stunt Coordinator

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    Allan, What do you think of this switcher?

    http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F003%5F010%5F011%5F000&product%5Fid=15%2D1216

    This seems like it would work, based on what you said. I'll also have to get RCA to F adapters.

    I just did a search on ebay for an external de-interlacer. The ones that came up seem to only output DVI, which isn't an option. If I understand you, there are older models that output component. If so, does the unit upconvert S-Video and composite to component?
     
  7. ChristopherDAC

    ChristopherDAC Producer

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    That's the whole idea. There are any number of these things, some of them made to drive projectors, others just plain deinterlacers, which take a composite, S, or component NTSC/480i input [typically] and output component 480p [typically -- though there are other output formats, anything from 720p to 960i or 1080i, and some are selectable], in YUV and/or RGB, RGBHV, VGA. Remember that composite or S connections are incapable of handling anything other than a plain NTSC signal.
     
  8. Jon Bell

    Jon Bell Stunt Coordinator

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    Thanks for the help, guys. That sound you just heard is the sound of technical stuff going over my head.

    First, an update. The "split and merge" method worked like a charm. I now have two selector switches that I can use to switch from DVD and HDTV to LD.

    Now, getting back to the deinterlacer. If I understand Christopher, all of your outputs (composite, S and component) go into the unit. They get converted to component. The component output goes to TV or projector. Other than the upconversion of the input, is it also supposed to improve the signal?

    Where do you buy these? Is $200 a normal price?
     
  9. JasonGabler

    JasonGabler Auditioning

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    Not that I've ever seen. Transcoders/converters are EXPENSIVE... at least two if not three to seven times that price depending on how fancy you get.

    jason
     
  10. Allan Jayne

    Allan Jayne Cinematographer

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    $200. may get a secondhand first generation iScan de-interlacer on eBay. New iScan models I believe start at $500. They all output your choice of 480p RGB or 480p component video (built in transcoding).

    All VGA projectors and all 480p and HDTV grade projectors have built in de-interlacers which may or may not be equal to or better than iScan external de-interlacers.
     

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