Author Topic: TV Questions  (Read 3829 times)
Ash
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Re: TV Questions « Reply #15 on: July 21, 2016, 01:33:39 AM » Author: Ash
2nd monitor
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Medved
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Re: TV Questions « Reply #16 on: July 21, 2016, 03:29:47 AM » Author: Medved
What i do see is that the image is darkened in teh perimeter and this burn in effect - What i assume is some loss of liquid as it probably cracked somewhere in the edge as result of the impact

Isn't that just the edge running warmer due to the lamp heat (or colder because the electronic heats up the center part from behind)? The LCD itself is quite temperature sensitive and it is the task of the complete panel maker. Usually it is in the form of a rather thick aluminum sheet just behind the panel, equalizing the temperature, usually acting as well as the main structural frame.
But if this sheet is too thin (because someone want to save mass at low cost) or inadequately heated (because of a poor thermal design of the complete TV or because of some fault developing there), the temperature differences across the panel area may become larger and so cause uneven parameter shifts.

Real LC leaks create sharp terminated areas where the panel does not respond at all. The thing is, it is mainly the surface tension, what keeps the optimal thickness of the liquid film and the same mechanism does not allow it to become any thinner or thicker, so the fill may be only completely missing in the defective areas.
« Last Edit: July 21, 2016, 03:33:17 AM by Medved » Logged

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wattMaster
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Re: TV Questions « Reply #17 on: July 21, 2016, 09:16:07 AM » Author: wattMaster
Wow, LCD screens are complicated!
I don't want to use it as a second monitor because all of the computers are laptops and I already have 3 spare monitors.
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Ash
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Re: TV Questions « Reply #18 on: July 21, 2016, 01:58:27 PM » Author: Ash
This effect appears from the 1st second the screen is on. I dont think it is thermal related. The edges are black and not responsive, but the border between the good and bad areas is not sharp. IIRC this is a panel with backlight from the back and not from the edge (backlight box made as a sun bed with diffusers over it). The blackkening is uniform along all 4 edges
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Medved
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Re: TV Questions « Reply #19 on: July 21, 2016, 02:10:28 PM » Author: Medved
Or it could be just a manufacturing parameter shift on the edge (larger distance from or wrong angle of the source of the deposited material when the different layers are deposited onto the glass surface), so e.g. higher Vt of the transistors not allowing to charge the pixels completely within the time window the controller gives to the selected lines.
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Re: TV Questions « Reply #20 on: July 21, 2016, 06:26:26 PM » Author: wattMaster
Maybe it's a software issue, and the processor is not working ciphers toy or the circuit is acting up. Mayen the transistors are failing? Or maybe you knocked a piece of metal making a short somewhere.
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Ash
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Re: TV Questions « Reply #21 on: July 21, 2016, 09:37:26 PM » Author: Ash
This TV had a fire in the PSU, but in the PFC part of the primary. I doubt it had any overshoot on the secondary. I run it with a PC power supply. Besides the effect looks definitely like something physical with the panel and not with the processor
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Re: TV Questions « Reply #22 on: July 21, 2016, 10:34:43 PM » Author: wattMaster
This TV had a fire in the PSU, but in the PFC part of the primary. I doubt it had any overshoot on the secondary. I run it with a PC power supply. Besides the effect looks definitely like something physical with the panel and not with the processor
Maybe it's that the panel is crushed at an angle and the Liquid Crystals can't twist as easily.
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Re: TV Questions « Reply #23 on: July 22, 2016, 07:05:35 PM » Author: wattMaster
Can we think of any other uses?
Update: I found a use for it. A friend is lending us one of her TVs, so we will replace it with the new one when they want it back.
« Last Edit: July 22, 2016, 09:16:16 PM by wattMaster » Logged

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