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camcorder viewfinder not good after repair

Discussion in 'Electronic Repair' started by [email protected], Jan 28, 2005.

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  1. Guest

    Model ccd-tr75 Sony.
    Have replaced all smd caps to make all camera functions work very well;
    only the viewfinder appeared blurry.
    So I proceeded to also change 4 mini caps on the viewfinder board and I
    now have a blank screen (no video/image).
    All circuit have been rechecked for shorts etc, and all is correct as
    per schematics so my question is where could the problem be considering
    this:
    a)one cap (220uf 6.3v)was open/dried and I replaced with a 220uf/16v
    b)one cap (82uf/10v)had high ESR and I replaced with whatever was
    available being a 100uf/16v
    Please, can anyone advise if changing these caps ( both marked SXE on
    the schematis?) could have caused something to go bad? (my tests are
    getting me nowhere and the only thing I notice is that the fbt area
    gets quite hot)
    Thank
    Jim
     
  2. Guest

    An 82uf cap is an odd value so I would imagine it's has a specific
    pupose. You don't mention what circuit these are being used in but
    changing the characteristics of a cap can change the resonance,
    impedance (changing the current), and/or filter (changing the
    frequency). So you should replace the caps with the same value and type
    (mica, electrolytic, mylar, etc) as the ones you removed. The voltages
    value of the caps aren't that critical, as long as you use the same
    value or above, but for micro-electronics you should always stay close
    to the original value.
     
  3. Guest

    Many thanks for your comments; the 82uf cap has the +ve to the
    deflection yoke and the -ve to the FBT.
    Following your info, I am now going to put in the circuit the old cap
    and if this is the problem then I would think the viewfinder should go
    back to its prevoius state (blurry video). Theoretically this should
    work; fingers crossed.
    Thanks, Jim
     
  4. have you try to set focus after your repair?
     
  5. Guest

    Hey,
    Could you please tell me more about setting the focus as this is my
    first camcorder repair.
    Much appreciated if you would.
    Jim
     
  6. quietguy

    quietguy Guest

    Just butting to say that my Canon has a small slider under the viewfinder
    eyepiece - this controls the focus of the viewfinder, not the camera - I
    would suspect the Sony has a similar arrangement

    David
     
  7. Allan

    Allan Guest

    I think he is talking about the internal Electronic Focus Control,
    Not the external Eyepiece adjustment.
    There is usually 2 pots, that you can adjust,
    One for Brightness and another for focus.
    But I think by the problem you have,, its Cap juice under components on the
    Evf, which can be a real bugger to remove.
    Allan
     
  8. quietguy

    quietguy Guest

    While of course you may be correct, it does seem wise to ensure the externally
    adjustable focus is OK before looking for faults

    David
     
  9. Guest

    Thanks fellows, but .....:
    I have just removed the 100 uf cap that I had replaced the original
    with and put in the correct value being 82 uf (found at Speedy Spares
    Melbourne). So the video came on good but I noticed a slight flickering
    occasionally. Anyway about 5 minutes later all went blank, no picture
    no light on crt of the virewfinder.
    Tested things and found one shorted diode a one shorted transistor near
    flyback.
    How lucky can one get?
    Can anyone please tell me why this happened? ( perhaps these components
    were already going bad)
    Jim
     
  10. James Sweet

    James Sweet Guest

    Quite easily the bad capacitor caused them to pop.
     
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