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Whining 100 Hz PHILIPS TV w vertical bars

Discussion in 'Electronic Repair' started by Matti Kaki, Jan 21, 2006.

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  1. Matti Kaki

    Matti Kaki Guest

    Hello from Finland.

    I have Philips TV 29PT8702 chassis: MD2.12E which whines a lot.
    It has also odd phenomenon which looks like ringing or ghost.
    Few vertical bars on the left and the right part of picture.

    I have varnished the L.O.T. and linearity coiletc. but no help
    at all. The whining comes (I'm quite sure) from L.O.T. I took
    few pictures if you like to take a look of the phenomenon.

    http://www.sci.fi/~oh2bio/hilipsi.jpg

    I remember that I have seen this phenomenon in Barco monitor
    and it was caused by bad voltage. I checked the voltages from
    PWR but they were quite OK (if I haven't missed one or two).

    Thanks a L.O.T!
     
  2. Did you also measure the ripple on these voltages? I had a similiar error
    with an older ITT tv set caused by a bad cap in the 12V-branch.

    Whining on another set was caused by bad B+-cap.

    I?d simply test the caps for high ESR.

    HTH,
    Sebastian
     
  3. Matti Kaki

    Matti Kaki Guest

    Yes I tested the ripples but it is possible I have missed
    one or two voltages because Philips TP-markings are terrible.
    Allright. I'll measure again or just replace the capasitors anyway.
     
  4. Matti Kaki

    Matti Kaki Guest

    I now took a stethoscope and removed the chest piece and listeded
    with the tube and the whining is NOT comiming from the L.O.T but
    from the power transformer. The sound circulates so nasty that it
    is impossible to locate the whining using only my ears.

    So there must be sometkihg. I measured the ripples once but must
    do it once again. Any ideas (modifications)?
     
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