I am in the market for a 65" FALD LCD.
I have read lots of reviews and forum threads here and am shocked
how many people have horrible looking screen problems that seem to have cropped up in just the last few years.
There seems to be three variations:
- Dark spots in all 4 corners ( vignetting)
- DSE - random blotches 1" - 4" in size where the screen appears a little dirty - hence the name Dirty Screen Effect.
- Banding, where the DSE is in regular vertical rows and may even show what may be FALD LEDs
1. Its shipping damage, or, it was fine when it left the factory.
If the screen is cracked - sure I'll buy that. For DSE, I don't see how improper shipping could cause it. Has anyone ever been able to deliberatly cause DSE? e.g by pressing hard on the screen? Sure you can deform the screen enough to make a spot but a spot is not a large variable DSE blotch. That excuse is even less likely for banding where you have to believe that the shipping damage is repeated uniformly across parts of the screen. Unless the tv was laid flat on a cattle grid and the UPS driver jumped on it I dont see any way for that to happen.
2. It's normal - all screens have some variation so you are being too picky.
Hell no! My 10 yr old LCD's both display grey screens well with just a little color variation but no DSE, banding or vignette ( to be fair neither are FALD). And, from the recent good reviews of presumably cherry-picked units and from winners of 'the panel lottery' it is clear that it is possible to make a uniform 4K FALD LCD.
I am a retired Broadcast engineer and NOT a TV panel expert but in my opinion the most likely cause of DSE & banding is non-uniform deposition of material for a layer of the screen ( phosphor perhaps?) AT THE FACTORY!
Corner vignetting is perplexing in that it seems so common that it may be more of an engineering limitation of FALD ( getting light into a corner) vs manufacturing consistency - why not then make corner LED's brighter?
This leads me to conclude that occasional DSE and banding are just a normal part of the screen manufacturing process but some manufacturers are choosing to ignore the x% of 'bad' panels and pass them through Q.A. to consumers -presumably because the only other option is to trash the panel.
Question - what happens to a banding return to AZ or BB? Does it then get trashed or (scary) resold elsewhere?
1. Keep returning until you get a good one. Many here are doing just that but I suspect that the number of returns is not yet high enough to cause TCL, Vizio etc enough pain to improve QA.
2. Ask reviewers to give more weight to uniformity vs other measurements because bad uniformity cannot be overcome - it ruins the viewing experience.
Say Rtings reviewed some new TV and it got 10 out of 10 for every picture quality test except Uniformity which got a 4. The total score would be high - but would you want that TV? Not me.....
3. What about a LCD 'panel lottery' scorecard on AVS - 'how many returns of model xxx have you made?'
Admin could ensure one entry per model per user
results would show:
Make, Model, Total Users, Average number of returns(lower is better)
Not particularly accurate since happy customers are less likely to post but it may help to shame the offenders with worst QA.
Any other ideas?
Also I would like to hear from a Panel Manufacturing expert on what is really happening and why it seems to have gotten so much worse than a few years ago.