Performance Variation Between Units Of Same Model TV / DVD players?.. (1 Viewer)

[Rich H]

> edited <

This question is for anyone, although perhaps the pros on this board who see a lot of equipment are in the best position to answer.

Has anyone experienced sample variation when comparing two or more units of the same model display or DVD player?
In other words, one unit performs slightly better or worse than other units of the very same model and make?

I've experienced sample variation between quite a few electronic devices (for instance, when shopping for my Canon S45 digital camera, I found the LCD screen on some S45 units functioned better than on others).

I've had two units of the same Panasonic 4UY plasma. The second unit seemed to produce a subtly, but noticeably sharper picture (on my reference DVDs, tiny details like foliage that were slightly blurred on the first unit would remain crisply rendered on the second unit). I'm able to achieve a level of picture clarity that I could not quite achieve from the first unit (although the first unit functioned very well too).

So, perhaps it's best to ask the pros who constantly fiddle with different units of the same model: have you experienced any noticeable sample variation, in terms of performance, between different units of the same model TV or DVD player? I know Joe Kane, for instance, has written about measuring "never the exact same voltage" between units of the same DVD player.

Just trying to figure this out...

 

[Rich H]

Bump.

Anyone?

Can any pros comment on this issue?

Thanks.

 

[Bob McElfresh]

Well keep in mind that unlike the display in your digital camera, there are LOTS of adjustments on a modern HDTV. And these have to be adjusted after about the first 100 hours of use with the TV settled. Physical movement, age, temperature, etc., all have an effect.

Then you DO have the issue of +/- tolerences on many of the electronic parts. These are considered acceptiable BECAUSE controls are added to allow adjustment.

So it's kind of hard to comment on manufacturing variations because televisions are known to have these issues.

There IS an electronic-test industry that tracks things like this. A few years ago Sony actually stopped testing a lot of circuit-boards as they came off the assembly line claiming that their defect rate was so low, the testing was not needed. Others view this as "let the customer be our tester". This shoves things off to the the retail outlets.

 

[Rich H]

Thanks Bob. Interesting about Sony.

My original Panasonic plasma unit was replaced by Panasonic Canada, after I'd brought it in for testing (it's a long story, but ultimately there was nothing truly wrong it). That one looked as good as any I'd auditioned in the stores. But this next unit showed up, with slightly different software (at least in the menus) and it just flat out looked better. When I came in to pick the replacement unit up the tech guy was looking at test signals on it. He remarked that it seemed a bit better than my first unit. I didn't think of it until I noticed myself with DVD images.

I tend to rave about the clarity of the plasma image, but occasionally I wonder if in fact I lucked out and am getting a smidgen more clarity from this unit, vs what some might be seeing from other units. I dunno.

(And, I compared my RP-91 DVD player to the RP-82 which shares the same video DAC. The RP-82's image was slightly, but distinctly, softer and smudgier at the edges. I'd have guessed they'd look the same...but perhaps I got a very good RP-91 unit or a slightly worse than normal RP-82 unit).


Still, I'd be curious if an ISF tech reported that, in testing TVs or DVD players, he ended up having to use different picture values to achieve the same calibrated image from two units of the same model.