Ok so a bit of a long winded post but noticed a few posts on various KU models with all with the same fault.
*TV turns on, backlight flashes then back to standby repeats
So I fairly recently acquired a 55" (from memory ue55ku6700) one of these with a cracked screen for free that I intended to use for parts, however upon switching it on it had the above fault. These models do not use a tcon, disconnecting the mainboard and the backlight comes on and all voltages from the PSU are accurate. Disconnection the panel from the mainboard and the fault returned. So I assumed not only does it have a cracked screen but also a bad mainboard.
Never the less I kept the parts,
So a few days ago a friend of a friend calls me to say he has a faulty UE55KU6470 this time the fault is similar to the old as15-f gamma faults, blues were washed out and reds were hazy.
So I decided to unplug half the screen just to see what happened, and surprisingly it doesn't turn on and instead starts boot looping. I disconnect both and again it's looping.
So I put in my previously though faulty mainboard reconnected everything and it powered on fine with perfect image and no gamma fault.
So to summarise, these TVs don't turn on if you disconnect the panel, they loop, if you have a cracked one thats shorted a driver it again won't turn on.
Also if you have one and have already replaced the main board and it's still looping then there's a far higher chance that the panel is shorted rather than the mainboard you've bought being faulty.
Personally If you see someone selling one with a similar fault its probably worth avoiding. If you're fixing one for someone ask if before it failed if there were any vertical lines before it conked out.
Might help someone
*TV turns on, backlight flashes then back to standby repeats
So I fairly recently acquired a 55" (from memory ue55ku6700) one of these with a cracked screen for free that I intended to use for parts, however upon switching it on it had the above fault. These models do not use a tcon, disconnecting the mainboard and the backlight comes on and all voltages from the PSU are accurate. Disconnection the panel from the mainboard and the fault returned. So I assumed not only does it have a cracked screen but also a bad mainboard.
Never the less I kept the parts,
So a few days ago a friend of a friend calls me to say he has a faulty UE55KU6470 this time the fault is similar to the old as15-f gamma faults, blues were washed out and reds were hazy.
So I decided to unplug half the screen just to see what happened, and surprisingly it doesn't turn on and instead starts boot looping. I disconnect both and again it's looping.
So I put in my previously though faulty mainboard reconnected everything and it powered on fine with perfect image and no gamma fault.
So to summarise, these TVs don't turn on if you disconnect the panel, they loop, if you have a cracked one thats shorted a driver it again won't turn on.
Also if you have one and have already replaced the main board and it's still looping then there's a far higher chance that the panel is shorted rather than the mainboard you've bought being faulty.
Personally If you see someone selling one with a similar fault its probably worth avoiding. If you're fixing one for someone ask if before it failed if there were any vertical lines before it conked out.
Might help someone
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