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VCR schematics

Discussion in 'Electronic Repair' started by [email protected], Jun 25, 2004.

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  1. Guest

    Dear Members: Where can I get (free I hope) a schematic

    for any VCR model? Specifically I need a schematic of the

    motor control circuit that keeps the main DC servo motor running

    at a constant speed....that think they are referenced to a 30 HZ signal.

    And, could anyone tell me if the reference is crystal controlled?????

    Best to all,

    Steven
     
  2. Many if not all vcr's reference can be traced to the 3.58mhz color burst
    crystal. The vertical frequency divides down nicely to very near 30 hz which
    just happens to be the drum and control pulse frequency.
    That the 3.58 is critical can be demonstrated by the fact that most vcr's up
    until very recently wouldn't even turn the drum if the crystal was bad. I do
    think newer vcr's with their improved chips etc, do it a bit differently -
    at least that's what I've been told - but I don't troubleshoot too many
    $39.00 vcr's for drum servo problems, if you get what I mean. :)

    Mark Z.
     
  3. But keep in mind that this is for playback. For record, the reference
    must be the incoming video sync.

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