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Old 03-21-2019, 03:03 PM   #81
Unspun01
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Default Re: lg 60pz550 black screen, no power, etc

Quote:
Originally Posted by legonch View Post
However there were two horizontal lines on the bottom third of the screen that were black. One line was about 1/2 thick, the other, looked to be just a single pixel.

Bad news.

You were not careful enough and you damaged the panel ribbon cable and also the locking tab on the connector.

The ribbon cable is part of the panel and not repairable. I don't know what you did, but these are delicate and you must have pulled or yanked on it in some way.

The black plastic locking tab is easily lifted by finger nail and should not break unless you force it with a screwdriver or something...

You will not be able to fix this TV and you will need to use it as is.
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Old 03-21-2019, 04:20 PM   #82
legonch
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Default Re: lg 60pz550 black screen, no power, etc

ugh.

Okay. Guess ill pull all the boards off and try and sell them on ebay.

Throw the rest away. Dang. Not sure how that cable got ripped like that. It flipped behind the connector, and i just pulled it out really slow, beats me. Total bummer. Thank you again for your help!
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Old 03-21-2019, 04:29 PM   #83
Unspun01
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Default Re: lg 60pz550 black screen, no power, etc

You could try re-seating that ribbon cable in case it just wasn't pushed in or secured properly.

But chances are that you kinked or pinched it in some way.

Or use a laptop or pc to resize a smaller window that is not affected by the damage. It would still be equal to a 50" or 55" screen. Seems a waste to junk it.

Last edited by Unspun01; 03-21-2019 at 04:31 PM..
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Old 03-21-2019, 09:35 PM   #84
legonch
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Default Re: lg 60pz550 black screen, no power, etc

Thing wont come on in test pattern at all now. top heat sink on upper buffer board is super hot now.

Im wondering if something else is wrong. cant get any response with a test pattern, unless i remove lower buffer board. I dont know if lower board is fried again. Im tired of playing with it. I was trying to get it fixed for someone that is having a rough time, was going to give it to them
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Old 04-08-2019, 01:38 AM   #85
corellian
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Default Re: lg 60pz550 black screen, no power, etc

I have the same model and had to replace 4 Fairchild IGBTs.

Now the unit turns on and stays on but no picture.

Using a block diagram schematic (http://www.toms-service-manuals.com/...&Search=Submit), i disconnected LVDS and shorted control board test pads.

To my joy a clear test pattern emerged! It’s here i noticed the control board led flashing: two long followed by two short blinks. The schematic mentioned if the test pattern is showing but no display then suspect mainboard failure.

So I have been troubleshooting the mainboard as I cannot find a replacement online. Other than a surface mount diode reading a bit strange (in circuit), i cannot find the fault.

I have also tried pulling heatsinks and heating both BGA chips with a heatgun but the same error blinks are showing.

I have done LVDS connector to ground continuity checks and theres quite a few grounds scattered through the pins on the mainboard side but without a schematic I am stuck. All LVDS pins go to the BGA chip without the heatsink on it which I have already tried reflowing anyway.

I think the next step is to try baking the mainboard in an oven but I only have one that goes to 250c.

Alternatively legonch, could you check which pin son your LVDS connector (with the ribbon disconnected) are grounds?

Or would you consider selling me your mainboard?
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Old 04-08-2019, 02:07 AM   #86
corellian
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Default Re: lg 60pz550 black screen, no power, etc

Actually, itís a different model. Sorry was on the train. I will start a new thread
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