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Sound but no picture

Discussion in 'Televisions' started by shodan, Feb 19, 2003.

  1. shodan

    shodan
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    Hi,

    Asking on behalf of someone else...
    A Hitachi C28W440N, which regardless of the input (scart or aerial) I get sound but no picture! Nothing, complete blackness. Hitting the Menu button doesn't change anything and even following the instructions to increase brightness etc. didn't bring any changes.

    After turning the tv on (about 5 seconds) there is a click from the back of the unit. Sounds like a relay. But why would a tv have a relay????

    Anyway, any help greatly appreciated.

    Regdz
     
  2. Chris Muriel

    Chris Muriel
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    It could be a relay - or a thermal or overcurrent trip.
    I assume you do not hear the familiar crackle of the EHT (25-30kVolts) coming up nor the 15625 Hz line frequency.
    Modern TVs contain various protection devices which may include traditional fuses, soldered in fuses, fusible resistors , overcurrent trip circuits and thermal cutouts.
    I'm an electronics engineer - but would still probably need the relevant service manual to find out what's wrong.
    Could be anything from a transistor or FET through to the dreaded LOPT (Line OutPut Transformer).

    Chris Muriel, Manchester.
     
  3. shodan

    shodan
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    Thnkas Chris.

    I guess I just imagine the need for relays in TV!! Just goes to show I don't know what I'm talking about!

    I have advised them to get an engineer out or better still, request a new tv as it turns out it's still in the 1 year warranty.

    Thanks for taking the time to answer.
    Regards
     

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