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Making a Camcorder Viewfinder Work

Discussion in 'Electronic Basics' started by Captain Blammo, Nov 27, 2004.

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  1. I've got a viewfinder from a broken old camcorder, and am trying to figure
    the pinout for it. The camera itself actually works, so I can power it up
    and measure things, but I have no oscilloscope.

    There are 5 conductors, 2 of which are power. I'm pretty sure that one is
    horizontal sync, because I get the classic pattern of ~30 degree sloped
    lines moving slowly down the screen if I connect 2 conductors (I can't
    recall which just now) to a standard NTSC signal. I also get a fleeting
    distorted image for a couple of seconds before the pattern settles in.

    What's the minimum equipment I'm likely to need to figure out what is coming
    out of each conductor from the camera? Also, does anyone know what I'd need
    to strip out the horizontal sync from an NTSC signal and put it on a
    separate conductor? Something cheap, small and not power hungry would be
    good, because I'm trying to use it as a poor man's head mounted display.

    If it's any help, the viewfinder is from a very old Magnavox Easycam 8.

    Ewan
     
  2. Rich Grise

    Rich Grise Guest

    The minimum you'll need to figure out what is coming from each conductor
    is a 'scope and meter.

    I've just been perusing ebay, and it seems to be just thick with scopes.
    Buy as much scope as you can afford, if you really intend to build stuff
    like a PMHUD. :)

    If you need advice on which to buy, please post any questions.

    Good Luck!
    Rich
     
  3. Richard

    Richard Guest

    Hmm, don't know muuch about Magnavox but my service manual for a Sony
    CCD-TR78, 88, 98, 99, 514, 590, 614, 714 814 shows a 5 conductor flex
    going to the viewfinder board VF-102 as 1- 5V, 2- GND, 3- Video, 4-
    tally, 5- NC. a lot of these are very simular.
    Hope that helps

    Richard
     
  4. Hmm, don't know muuch about Magnavox but my service manual for a Sony
    Funny you should mention it, I actually have a viewfinder from a Sony
    CCD-TRV22 as well, but it only has the four conductors going into the VF-102
    board (Nothing on pin 5). Do you happen to know if scraping the surface off
    those cables is a good way to get at the conductors? I don't have the right
    connector to plug the end of the cable into. Also, does your manual mention
    what video format the viewfinder takes?

    Secondarily, and please do pardon my ignorance here, I'm not well versed in
    the art of pinout parlay. What does "tally" mean? I assume that "NC" means
    "Not Connected".

    Thanks for the info!

    Ewan
     
  5. Richard

    Richard Guest

    Hey Ewan,
    Took a quick look at another Sony I have in pieces. It has a 4
    conductor cable going to the viewfinder. It follows the same layout as
    above and yes pin 5 is No Connection. In this case just not there. Pin
    4 is Tally which actually is a video term for the little light that
    comes on when the camera is recording. (In a studio it's the little
    light on the top of the camera so the talent knows which camera to
    look at. It can also be turned off ) I put 5 volts from 1 to 2 (neg)
    and got the CRT to light up. If you open up the viewfinder you can
    find which pin goes to the LED that would be 4.
    I just use wires out of a Cat5 cable and shove them into the connector
    for testing. You could find one of the mating blocks (male) off some
    salvaged board (like junked VCR) and just cut out 4 pins mod it and
    plug it into this cable then you could solder your own cable up.
    Oh everything in this camera is NTSC EIA . Maybe I can play with it
    more tomorrow.
    Richard
     
  6. Richard

    Richard Guest

    Maybe I can play with it
    OK Ewan played with it a little this morning. Applying a standard line
    out video signal to Pin 3, OOhhh little tiny TV! but where's the
    sound? So that works as I thought 'cause I'd played with these before.

    Richard
     
  7. Rich Grise

    Rich Grise Guest

    I remember when my little brother was just barely able to sit up and watch
    TV, we were all in the car and Dad turned on the radio. Little bro started
    looking around at the windshield, dashboard, whatever, asking, "Where's
    the picture?"

    ;-)
    Rich
     
  8. OK Ewan played with it a little this morning. Applying a standard line
    Aha, well, I now seem to have the complete set of info for making it work.
    Thanks hugely, I'll try jamming some Cat5 wires in there and seeing if it
    works.

    By the way, shouldn't the other conductor from the video cable be connected
    to something? Should I tie it to GND, perhaps? Either way, as long as it
    works, I'm happy.

    Cheers!

    Ewan
     
  9. Richard

    Richard Guest

    Ewan,
    Hope this dosen't get posted twice. I posted last night but it hasn't
    shown up 18 hrs later.
    Yes that's right the ground is shared by everything. Use the solid
    wire as a temp thing and scab another connector to make a permanent
    connection.

    Richard
     
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