Using a Video Amplifier in between an Analog Video Camera & LCD Monitor

Discussion in 'Professional Video Production' started by Darren Harris, May 19, 2004.

  1. Can anyone tell me that if a video amplifier is placed in between an
    analog video camera and an LCD screen, will it correct a dark/high
    contrast picture?

    And if so, can I get recommendations on the best units to get?

    My video cameras works perfectly with a CRT monitor, so I figure the
    problem might be that something is lost in the conversion process
    needed to display the captured from the video camera on an LCD screen.

    Has anyone else had this problem?

    Any advice would be greatly appreciated.

    Thanks a lot.

    Darren Harris
    Staten Island, New York.
    Darren Harris, May 19, 2004
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  2. "dark/high contrast" sounds like it might be a termination
    problem. Baseband video likes to be terminated in a 75 Ohm
    load, are you sure your LCD input is terminated?

    FYI: No term = very high video level, high contrast
    Double term = very low video level, low contrast (washed out)
    (It's possible to double terminate video by accident too.)

    If you do have proper terminatin, and you're just getting
    rotten transfer of signal, you could try a "processing" amp.
    This will give you control of setup (black level) and peak
    video (white level), along with chroma saturation and phase.
    They come in all prices and flavors. When I was easing out
    of the business about 10 years ago, people were starting
    to make then right on a card for the PC, with software
    control of the levels. I can only assume those are still
    being made and have probably come down in price since then.
    I-zheet M'drurz, May 19, 2004
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  3. Darren Harris

    Larry Jandro Guest

    Waiving the right to remain silent,
    (Darren Harris) said:
    That depends on if anything really needs to be corrected.
    There is no specific "conversion" process used in LCD monitors.
    They decode video in the same way as a CRT monitor.

    CRTs are generally much brighter than LCDs, which usually also have
    an off-axis viewing problem.

    I suspect that you really don't have any problems, just the
    mistaken idea that a cheap LCD will make bright video.

    Larry Jandro - Remove spamtrap in ALLCAPS to e-mail

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    Larry Jandro, May 19, 2004
  4. Very unlikely. Something else is probably wrong.
    None. Keep looking for the real problem.
    Sounds like something is wrong with your LCD screen. Does
    it work with other sources?
    Probably. But you have offered insufficient information to help you.
    Richard Crowley, May 19, 2004
  5. Thanks.

    I'm in a jam, and really need to find out exactly what I should do to
    correct the problem outside of send the units back. There are a lot of
    "video amplifiers" on Ebay, but if they won't help, then I'm at a loss
    of what to do next.

    The units I have are two new Sansui 6" LCD/VCR combos(model number:
    CLD0065) that I had intended to use for recording on a trip I'm about
    to take.

    ***Note: I get a reading of 74.5 ohms at the video input of the units.

    As for more details of my problem. I hooked my older analog video
    camera which is a JVC Lolux(Model number: GX-N7U) to the Sansui
    LCD/VCR via a 10-pin AC adaptor(AC-C412).

    For some reason I can't get a decent picture to record. And the best
    picture I do get is when I use the "Fader button". If I keep my finger
    on this button, the picture I get on the Sansui will progressively go
    from a *very dark/high contrast* picture, to a *dim/washed out*
    picture. When I take my finger off of the "Fader button", it of course
    slowly returns all the way back to the original dark, high contrast
    picture. I can't get the picture to stay "in-the-middle". Not that I'm
    supposed to. Even if I could, that's not a "great" picture, but it's
    better than what is shown when I don't have the "Fader button"
    depressed, or when I leave my finger on the "Fader button".(I am aware
    that the "Fader" option is not the problem).

    I tried all three of my JVC(GX-N7U) video cameras with my regular
    TV/VCR combo unit and everything works fine, so the problem is
    obviously the Sansui LCD/VCR(of which I have two that exhibit the same

    Thanks a lot.

    Darren Harris
    Staten Island, New York.
    Darren Harris, May 19, 2004
  6. Yeah, I read all this last time you posted it.

    Then I asked the question: "What is this "10-pin AC adapter"?
    Does it somehow provide the A/V inputs/outputs to your Sansui
    gadget? Maybe it is broken."

    You never responded.

    And the other question you also didn't answer:
    "Does your Sansui gadget work OK with any other video source?"
    Richard Crowley, May 19, 2004
  7. Actually I did. I said "There's nothing wrong with the 10-pin
    adaptor(AC-C412), because the video cameras work perfectly with my
    regular TV/VCR combo unit."
    Actually, this question was never asked. Nevertheless, I assume that
    the TV tuner and also the VCR of the Sansui would be considered video
    sources? If so, they give me a perfect picture, so the problem as I
    mentioned is somewhere in the area between the Sansui video input and
    it's built-in LCD screen.

    Darren Harris
    Darren Harris, May 19, 2004
  8. You never responded.
    Thanks. I actually looked back through several threads, but you
    posted in several newsgroups and I may have missed it.
    Asked this morning at 6:22 am. (pacific time)
    Your post at 6:47 am didn't seem to acknowledge it, but
    was just a reproduction of your original question.
    Yes, but they are INTERNAL video sources.
    Your question is about the Sansui EXTERNAL input, is it not?

    If I read your original posting properly, perhaps you HAVE
    already conducted this experiment. You said that you camcorder(s)
    work OK into your "regular TV/VCR" but not into the Sansui. You
    have only to try some other kind of video source (like your other
    VCR or cable/sattelite box, etc.) to confirm that the external
    inputs of your Sansui units appear to be defective.
    In that case the Sansui(s) are clearly broken and must be returned
    and/or repaired. It should be easy enough to demonstrate that
    any camcorder produces unacceptable pictures on the Sansui,
    but works OK on other monitors/VCRs.

    You are trying to plug a completely conventional video output
    (from your camcorders) into a completely conventional video
    input (the Sansui TV/VCRs). It should work exactly as expected
    without any amplifiers, etc.

    Your reported results appear to indicate something seriously
    wrong with the Sansui external inputs. Don't let the fact that
    you have two bad units dissuade you from the obvious problem.
    Wouldn't be the first time that a manufacturer had a bad run of
    units off the production line.
    Richard Crowley, May 20, 2004
  9. The answer as well as the original posts were cross-posted. Perhaps
    there is a problem with your news reader.(I post to and read from
    Google groups).
    Since I post and view using Google, I wouldn't have seen it that early
    anyway, since it takes 6 to 9 hours for Google to update. But Google
    groups still show no such post/question. If you see it, then evidently
    there are problems with posts not showing up everywhere they are
    supposed to.
    Well the problem may have nothing to do with the external input. I'm
    thinking the problem is deeper, because if I use my DVD player as a
    video source the Sansui produces the correct image on it's LCD screen.
    To condense my response to what you said above...

    Basically, the Sansui LCD/VCR works perfectly with everything.(That
    includes it's internal as well as external video sources).

    And my JVC video camera works perfectly with everything.(That includes
    any of three different (CRT)TVs.

    ***But, if I connect my Sansuis to my JVC Video camera, all I get is
    that very dark(black) picture.

    It seems that I need a brilliant solution to what is probably a simple


    Darren Harris
    Staten Island, New York.
    Darren Harris, May 20, 2004
  10. "Darren Harris" wrote ...
    Sorry, I never saw a post reporting that you had tried anything
    but your camcorders into the Sansui external input. What did
    you use? How did it work?

    If you are saying that your Sansui works fine with OTHER video
    sources going into the EXTERNAL input, then indeed you have an
    extremely strange interaction between two pieces of equipment
    that I have never heard of before. I'd still try to take the Sansui
    units back if they won't work with your camcorders.

    Don't you have access to a real news server? Google is fine for
    looking up historic archives, but it is too slow for real-time use.
    The Google record is indeed missing some posts from you and
    some from me. I thought it was better than that. Oh well.
    Richard Crowley, May 20, 2004
  11. The JVCs(GX-N7U) are are video cameras.(Not camcorders). And since no
    ne makes anything like the Sansui units I have, taking them back is
    not an option.

    I guess I'll have to wait a while and try posting this again in hopes
    someone will come along with an answer to why the video camera and the
    combo unit work perfectly with other hardware but not with each
    other.(Or at least has an idea on what I should check next).

    Thanks a lot.

    Darren Harris
    Staten Island, New York.
    Darren Harris, May 21, 2004
  12. Darren Harris wrote:

    (late attempt to help)
    OK, just a few thoughts and questions that might help:

    The JVC camera, you're taking video from
    a(n) 5-pin S jack / RCA / BNC ? and you are 100% certain
    that it is composite video out (1V p-p full signal)?

    If there is *any* choice as to what type of video signal is
    coming out of that spigot, are you forcing it to be 1V p-p
    composite video?, or is it on (gulp) "auto"?

    The same basic question goes for the input(s) to the Sansui.
    The port you are going into, is it auto terminating, is there
    a switch somewhere for terminatin, either a physical one
    or possibly a setup function?

    Do you have access anywhere to look at the output of the
    cameras on a waveform monitor? To confirm that you have a
    full video signal on that output connector?

    Reason I ask ALL of this is that I'm sticking by my original
    assesment: You have a termination problem somewhere. Either
    from an "auto" setting gone haywire or an actual hard wiring
    choice that's not being made. CRT monitors can be forgiving,
    they too can "auto terminate" and fix the problem for you,
    the LCD may not be doing that.

    *Everything* you describe lead me to believe that the video
    from the camera is somehow not being terminated when it hits
    the LCD display, that would give you results you're describing,
    and also fits in exactly with the "hold the fader button so it
    stops half way" scenario. In that case, instead of this wild
    uncontrolled (usually about 3V p-p instead of 1V) unterminated
    video, your fader is pulling it down to a more normal level
    when it hits that swet spot in the middle of the fade.

    To summarize what I would check: What's coming out of those
    ports on the cameras, and how is the input to the LCD handling

    Good luck!
    I-zheet M'drurz, May 21, 2004
  13. I STILL haven't see an answer to the question "What did you use?
    and How did it work?" (four paragraphs above)
    Richard Crowley, May 21, 2004
  14. Guess what? I tried the JVC/Sansui combination today and I finally get
    a decent picture. At first, I couldn't figure out what was the
    problem, so I tried to duplicate it so that I 'd know not to blindly
    run into into it again. I changed the audio wires around, used a
    different but identical adaptor, and even changed the postion of all
    involved hardware. Nothing. Then something totally unrelated happened.
    OThe second of two bulbs in my ceiling light came on. It's been doing
    that perhaps a couple of times a day lately because I guess it is not
    completely screwed in, and I was too lazy to tighten it, because I
    prefer the light I get from a single bulb anyway. But this time it
    came on when I had the JVC hooked up to the Sansui. Bingo! Evidently
    the video signal was weak because there just wasn't enough light, and
    that extra bulb corrected the problem. A problem that would not be
    apparent with other video sources like my VCR, TV tuner, or DVD. Of
    course I get a perfect picture when I use the JVC video camera with
    any of the other TVs I have(under the single bulb condition), but
    evidently the Sansui has a higher threshold. And I assume that the
    video cmera itself was strained to send a lighted image also(even
    though it is a Lolux). So basically the amount of light was just a
    little inadequate for the JVC/Sansui combination I was using. Yes, I
    know that the Sansui LCD/VCR is not a high quality item, but at least
    there are no major issues with it, yet.

    If that bulb didn't come on at that exact time, we may not have ever
    found the problem. :)

    Thanks a lot.

    Darren Harris
    Staten Island, New York.
    Darren Harris, May 21, 2004
  15. I offered all the information I could think of.(I know nothing about these things).

    Nevertheless, the problem is corrected.


    Darren Harris
    Staten Island, New York.
    Darren Harris, Jun 15, 2004
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