From what you describe it might be a mainboard issue, more specifically something related to the logic of the TV like the CPU. Given that it takes around 20 minutes to hang, it could be related to thermal stress on the CPU, could be cold or cracked joint on one of the solder balls underneath the CPU, in that case a fix would either necessitate a reflow, reball of the CPU or replacement of the mainboard itself. Of course I cannot assure that without further information, but it would be a good place to start.
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From my experience, if a tv shows the standby light and refuses to power on it indicates this type of issue. You might have gotten it to start once or twice by pure luck when the solder joints where making slight contact.
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Check out this [link|https://www.youtube.com/watch?v=tvgXk-m8idc&ab_channel=surfncircuits|video|new_window=true] of someone attempting a reflow using a hot air gun, keep in mind these are not the proper tools, but If you have nothing to loose and want to give this a shot before buying a new mainboard go ahead! Be careful when working with TV's as they could contain dangerous voltages even after unplugging, only do so if you're comfortable and leave it unplugged for a while.
From what you describe it might be a mainboard issue, more specifically something related to the logic of the TV like the CPU. Given that it takes around 20 minutes to hang, it could be related to thermal stress on the BGA solder connection of the CPU. Of course I cannot assure that without further information, but it would be a good place to start.
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From what you describe it might be a mainboard issue, more specifically something related to the logic of the TV like the CPU. Given that it takes around 20 minutes to hang, it could be related to thermal stress on the CPU, could be cold or cracked joint on one of the solder balls underneath the CPU, in that case a fix would either necessitate a reflow, reball of the CPU or replacement of the mainboard itself. Of course I cannot assure that without further information, but it would be a good place to start.
From what you describe it might be a mainboard issue, more specifically something related to the logic of the TV like the CPU. Given that it takes around 20 minutes to hang, it could be related to thermal stress on the BGA solder connection of the CPU. Of course I cannot assure that without further information, but it would be a good place to start.