Plasma TV Conundrum

Black Patches on Plasma TV Screen when TV's Off

There seem to be a number of solutions. Read on.

I was recently very kindly donated a used forty-inch Panasonic plasma TV in perfect working order but with large black patches on the screen when the TV's off but which are actually clearer areas and thus mostly invisible when the TV's on and displaying video. Despite that, having something of a life-long passion for audio and video tech, I'm tempted to attempt a fix.

Above image: Plasma TV, off, with black patches on screen

Above image: Plasma TV revealing that the black patches are actually clearer areas of the screen when the TV's on

Above image: Plasma TV displaying a TV broadcast, revealing a good picture quality, the clearer patches invisible

I couldn't find anything specific to the issue on the web and a discussion on an audio-video technology forum proved insufficiently helpful, although I appreciate everyone's comments.

Looking at the screen at a wide angle, I noticed that there appeared to be two screens, one a little behind the other, which led me to think the front one was merely there to protect the one behind, which was the one actually part of displaying the TV picture. This led me to suppose that there might be some or other film or coating on one of the screens; a closer look suggested it was the front one that was involved and that the coating or film had been applied to the back face of it. I imagined the coating might be there to, say, mitigate reflections from the screen behind being re-reflected thus causing the same double-image effect you get with double-glazed windows. I was tempted to think, as a starting, default, position, that the "black" patches, on account of covering a smaller area of the screen, were the anomaly rather than the grey, covering the overwhelmingly greater portion.

Finally, some more web searching led me to an audio-video forum with a wealth of relevant information. It was almost certain that my TV had either a coating or film of anti-reflective/anti-glare material. And I'm pretty sure that the screen is meant to be black when the TV's off, the other reason for the coating/film—to enhance the picture black level and, thus, contrast; the grey area is the anomaly.

I managed to get a look at the service manual for the fifty-inch version of the TV and it looks a simple job to remove the TV's plastic screen surround (bezel), which holds the front glass screen.

Options currently include the following:

• If it's a film: without removing it, play a hair-dryer on a low heat setting over the back of the film in the hope the adhesive on the other side will melt slightly, enough to adhere the lifted area of the film, the area seen as grey, gently running a paint roller over it to distribute the adhesive and flatten the film down. If the film won't stick, remove it, clean off the adhesive from its back and the back of the front screen, apply fresh adhesive and stick back down. If the film becomes defective, purchase a car window tint film and adhere that to the back of the screen. Actually, it may be a better idea to adhere the film to the front face of the screen so that if there is a problem with it in future, it can be quickly replaced without having to remove the front of the TV.
• If it's a coating, or the film method doesn't work: clean off the coating and spray with car window tint spray. Again, this may be better applied to the front of the screen so, again, if there's a future problem, the front of the TV won't have to be removed. One thing to bear in mind with a spray-on tint is that care must be taken to cover the area uniformly, otherwise there'll be lighter and darker areas.

Stay tuned!