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Hitachi L19HP03U TV

Discussion in 'Troubleshooting and Repair' started by markm6164, Feb 23, 2012.

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  1. markm6164

    markm6164

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    Jan 22, 2012
    I bought another TV today to have a play with. The Tv has standby light but doesn't power up. After basic testing i found a couple of 12v supplies from the PSU missing. This is great as its directing my learning to SMPS once again. Anyways i have attached some pictures below. The 12v feeds that are missing are on the smaller 6 pin connector. Once again if anyone has a schamatic that would be good but i think no one will. What are your thoughts?? I also have a audio unit from a car that won't power up i might start a thread on later if no one minds.

    DSC03708.jpg DSC03709.jpg DSC03710.JPG DSC03711.JPG DSC03712.JPG
     
  2. markm6164

    markm6164

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    Jan 22, 2012
    [​IMG]

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  3. davenn

    davenn Moderator

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    1,856
    Sep 5, 2009
    hi Mark

    ok a couple of closer up and muuch sharper pics of the left half of the board sides shown in pic 1 and right half pic 3

    Hint... When posting pics of boards ... make sure that you orientate them the same way, it makes it easier to do circuit tracing from one side of the board to the other

    what are the 2 devices on the heatsink behind the 3 electro caps ? part # ?
    I suspect they are rectifier diodes
    you would need to see if you have voltage on the output pins once identified.

    Dave
     
  4. markm6164

    markm6164

    118
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    Jan 22, 2012
    Hi Dave

    I will post better pictures later tonight. Those devices on the heatsink are rectifier diodes (SP10150) and the output is 20v. Thats on the good side, the missing power i have are on the other plug. I notice on the 6 pin plug there is an on and off pin. Maybe thats why there is no power at that plug? What will i be looking for on that pin? I am missing the two 12v supplies on that plug.
     
  5. davenn

    davenn Moderator

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    Sep 5, 2009
    hey Mark

    well it is always possible there there wont be any power out on those 12V pins unless
    something further along the trail is switching. Some systems do that.
    You may need to trace that on/off line(s) to where they go there could be a voltage level generated somewhere that if it doesnt get back to the PSU then it inhibits the 12V from leaving the PSU board

    Dave
     
  6. markm6164

    markm6164

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    Jan 22, 2012
    Thanks dave

    When psu is powered up something on the power board clicks but i can't identify what. Also when the power board is connected to the tv the standby led flashes with the same rate as the clicks on the psu.
     
  7. markm6164

    markm6164

    118
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    Jan 22, 2012
  8. markm6164

    markm6164

    118
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    Jan 22, 2012
    UPDATE:

    I was getting nowhere with the smps so I bought a replacement and now all is working. Thanks for your input.
     
  9. davenn

    davenn Moderator

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    Sep 5, 2009
    hi mark, yeah with SMPS's as I commented in the other thread its often difficult get get them running again unless the faults are relatively straight forward.

    One thing tho, and thats for the link to that manual site, neither of those 2 units shown in either manual were for AC input power supplies. BOTH were for 12V DC inputs, obviously coming from a 120/240VAC to 12VDC SMPS plugpack.
    So I'm not sure what the variation is that you have

    Take care
    Dave
     
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