Toshiba 55" LCD no picture

Discussion in 'General Electronics Chat' started by bwilliams60, Aug 13, 2014.

  1. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    55G310U Toshiba 55" LCD TV has no picture when turned on. Green power light comes on, backlight comes on, no sound, no picture. I know there is bulletin on bad inverter boards on this unit. How can I be 100% certain that is what it is?
     
  2. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
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    You can't.

    But almost certainly you have a PSU failure. "Bad inverter" usually refers to the backlight inverter, but you say that is ok.

    I would chase down the PSU, and check it's output rails against the service manual or schematic specs. If you have no manual or schematic then examine the PSU the fault is quite likely to be dried out small electro caps, often the ones close to hot parts.
     
  3. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    Ok here is an update. I checked all the voltages on the power supply and they are as they should be. I got loking around the TCON board in the top center section and found that it had been apart and the ribbons at the top had not been reconnected. So I reconnected them and put everything back together and turned it on. Here is what happened.
    The green light came on for power, the screen went a whitish blue and had dark horizontal lines across it for a few seconds and then blanked out and then the top one third of the screen did this again and then it slowly faded into darkness into the top left corner. No change after that.
     
  4. ScottWang

    Moderator

    Aug 23, 2012
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    You should attach some clearly pictures is better.
     
  5. MrChips

    Moderator

    Oct 2, 2009
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    Sometimes I like to know the history behind the broken gadget. This can help with the direction the trouble shooting takes.

    Is this your TV? Did you see it working before the fault developed?
    So this isn't your TV. It was given to you or you acquired it from ewaste recycling?
    You opened it and found multiple ribbons not connected.
    So it was already broken and someone else had a go at it.

    That puts trouble-shooting on a different track.
     
  6. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    Mr Chips,
    You have done your homework and/or read between the lines but you are correct, this was not my set and someone else has fiddled inside. It was a drop off at a recycler and the story goes that it would cost $1200 to repair it so the people dumped it. I have made progress as I went to check the fuse on the TCON board and lo and behold, under better lighting, I noticed the AUO-12401 Chipset had blew up. Now leads me to wonder what else I will find. Fuse was okay by the way.
     
  7. MrChips

    Moderator

    Oct 2, 2009
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    I say you have two choices:

    1) Let it go and send it back to ewaste.

    2) Put it in storage and wait for another same brand and model to come your way.
     
  8. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    Actually, there is a website called ShopJimmy.com that sells this TCON board for around $40. The rest of the set doesn't look like it has been disturbed but I might take a chance and get the board and try to fix it. Nothing ventured, nothing gained right?
     
    Metalmann likes this.
  9. ScottWang

    Moderator

    Aug 23, 2012
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    How about the caps on the power board?
     
  10. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    The caps on the power board are all good. People head straight for them because there is so much coverage on Youtube. This is not a PS problem. I checked all the voltages from the PS first thing and they are all bang on at 24V, 12V and 5.1V. Thank you for the thought though. I am going to order a TCON board and see what else I have. Maybe if I am lucky, a new 55" big screen for another room in my house, or garage ;)
     
  11. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    Update. I replaced the bad TCON board and turned it on. Same result. I am sure the board was bad as you can see from the picture. Lights off I can see the backlight but there is no picture or sound. A flashlight on the screen indicates nothing. Any ideas?
     
  12. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,036
    Get out while you can? Seriously, I know how hard it is to walk away but at some point you have to get realistic about the odds of success versus the work to get there. As Dirty Harry put it, "A man's got to know his limitations."
     
  13. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
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    I don't recall Dirty Harry ever giving up, lol. Anyways, I only have like $25 for a TCON board into it so far. This is a 55" Toshiba. I'm sure I can get some $$$$ back out of it if I get it fixed. I want to know what I should be looking for next though. I am suspecting a signal from the motherboard is missing.I will go into in for about $150 before I give up.
     
  14. ScottWang

    Moderator

    Aug 23, 2012
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    The big IC of control board was burned out, do you want to change the IC or buy a new board?

    If you can't find the problem why caused it damaged, someday may happen again.
     
  15. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
    722
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    Thank you Scott but I always work on cause and effect. The IC on the TCON board was smoked and I would like to know why. I have a new TCON board but don't want to throw money into the fire by installing this board and waiting for the smoke to roll out of it. As you say, it will happen again. So I am on to this new episode where the board is in, running cool but I still have no picture. Just a half and half screen with opposite colored vertical and horizontal lines. It leads me to think I have MB issues but not enough experience to figure it out. I have a DVOM and a Picoscope (PC based scope) ready to explore. Any ideas out there?
     
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