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LCD help anyone?

Discussion in 'Do It Yourself (Not Computer-Related)' started by marc5879, Feb 11, 2013.

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  1. marc5879

    marc5879 Thread Starter

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    Ok so I have posted this around on sites trying to get help. I am now the proud member of like 10 new forums.

    I have a 46" Vizio that one morning just didn't come on. There were no issues the day before. Turned it off one night and it just never came back on. Here's what I looked at. All the power parts. I have checked resistors, all come in good. Fuse is good. All capacitors are clean and square ( I have no way to test them and no desire to pull out 50 dang capacitors). The one connection has "5Vx3, GNDx5, 12Vx3 and on/off". When I test I get the 5V coming through but not the 12V. So I bought a new power supply board thinking it could be in the transformers. Well, no dice. I have the exact same issue. 5V good 12V nothing ( I am now thinking the 12V comes through when the set powers up). Now I am wondering if it has something to do with the on/ off switching. That may be in another board. I looked at that, same thing. all clean. When you hit the power in either the button or the remote, literally nothing happens. No lights on the power indicator, no sound no picture using a flashlight. It really would appear that when you tell it to power on it doesn't know how. It's out of warranty, and I don't have 300 to blow on a TV repair guy to say it's a 20 board. This completely a DIY so don't bother saying take it to a repair man. It will go to the heap before that happens. Not to mention it is already been replaced. But it would be a nice bedroom set if I can do it cheap
     
  2. Drabdr

    Drabdr Moderator

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    :D

    Welcome to TSG! I hope you find out of the ten that this is the place to stay. :)


    Was it off the night before? Judging by your post, it sounds like this is 101 that I'm sure you covered already. But did the board have any burn marks? Did the power supply smell like smoke or anything?

    I'm glad you stated that you didn't mess with the capacitors. I've got lit up by one of those. Once. ;) Too, I would think you would see something charred around them. If needed, maybe you could see if a neighbor or somebody has a capacitance tester, if you want to get to that part.

    I wonder if the 12V is even used. Could this be a generic power supply used in this set?

    Are you able to measure the voltage going to the power switch, and coming back from the power switch?

    And... just to add a basic, stupid question... I assume the power receptable is working fine and feeding the television the appropriate voltage. Maybe try another plug?

    :D And no. I won't suggest taking it to a repair person. That would be like me asking for directions! :D
     
  3. marc5879

    marc5879 Thread Starter

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    :eek: I had this all written up and it just vanished when clicked the more to see if I could add a picture!!!(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)(n)

    Gosh, Im gonna do this again but some what shorter.

    Thank you for your time Drabdr, of the posts I put out you are the only one to reply so thank you so much.

    "Was it off the night before? Judging by your post, it sounds like this is 101 that I'm sure you covered already. But did the board have any burn marks? Did the power supply smell like smoke or anything?"

    The night before was working fine. It was turned off for the evening and the next morn, nada. No stroms or anything, just like it decided to retire with no warning.

    "I wonder if the 12V is even used. Could this be a generic power supply used in this set?"

    No I actually think it may be set specific. All the part number come up the same set when I was looking for a replacement. I could be wrong though.
    The port that has the 12V has a harness connecting a wire to each prong and goes to the card with the the inputs. I believe that the 5V is the standby power and then somehow the on/off wire carries the signal to activate the 12V.
    So it looks like the 5V carries power to the card that when you turn it on send the signal back to the power card that activates the 12V DC. Purely speculation.

    "Are you able to measure the voltage going to the power switch, and coming back from the power switch?

    And... just to add a basic, stupid question... I assume the power receptacle is working fine and feeding the television the appropriate voltage. Maybe try another plug?"

    Here's the fun part. I have no idea where the on of switch is. I looked high and low and I can't see anything that even looks like one. I fallowed the on off button wire and it goes to the same card that he harness goes to. Hence the thought that the on/off is there somewhere sending the signal back through the on/off wire to the power supply card.

    The white wires are the button on of volume channel harness. The thick bundle is the harness carrying the 5V 12V on/off wire, and the card is the input card where all the wires lead.
     

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  4. Drabdr

    Drabdr Moderator

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    Nice pictures!

    So it sounds like the picture 1 is the one with the wires of interest. Correct?

    Isn't there an actual on/off button on the front of the TV that can be pushed? There should be wires going to it.
     
  5. marc5879

    marc5879 Thread Starter

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    Yes. Actually after you posted I tested the wires from the motherboard to the on off button. There is a 5v line. Tested it, nothing. So I am thinking that the juice goes from the power board to the mother board to the button board and back. I am thinking I may get a mother board unless you have another suggestion.
     
  6. Drabdr

    Drabdr Moderator

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    That sounds like your making a logical progression. I would think you would see something on the mother board that did not look right; since we are talking about power.

    If the mother board isn't that much, I would try it.

    However, do watch your Escalation of Commitment. You don't want to get too much money tied up in this. TV's are fairly inexpensive these days. :)
     
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