Video flicker / instability / dropout during white scenes (1 Viewer)

[Michael_Bechtel]

Hello all.

Lurked here for a few days, and am finally getting up the vocabulary and gumption to ask:

I've got an Onkyo TX-SR500 (branded HT-R500 as part of the HT-S650 home theatre in a box kit). I connect a Sony DirecTivo (sat-t60) and a panasonic DVD player (DVD-RV32K)to the receiver using composite video cables.

The problem is simply this:
Whenever the screen goes to all white (or possibly just from very bright to very dark (think explosions, etc)) the video signal gets "flickery" or "out of sync" for about 1/4 second.

I've read threads that suggest this could be the result of running video through one's VCR with macrovision, but unfortunately this isn't the case with my setup. I'm running the video straight from the devices, through the receiver, into the TV (composite video all the way).

Any suggestions/education you can provide is much appreciated!

Thanks,
Mike

 

[Michael Reuben]

This sounds like an issue with the TV, not with the source(s). What model is your TV? And has it been calibrated with a disc like AVIA or Video Essentials?

M.

 

[Michael_Bechtel]

This is a possibility. I haven't calibrated it yet, but by the same token, I've never noticed this issue when the dvd or Directivo were connected directly to the tv.

I'll check for the flicker tonight bypassing the receiver, and let you know tomorrow what happens.

Thanks,
Mike

 

[Michael_Bechtel]

Checked my setup with the composite video running straight to the TV, and the issue dissapears. Mixed blessing...I suppose I've controlled for the receiver as the culprit...but now I have to figure out if it's an adjustment issue or an outright defect.

Thoughts anyone?

Thanks,
Mike

 

[Dale Adams]

Mike,

This type of problem usually occurs when the output of a video source device is AC-coupled and the average DC level of the signal then varies with the picture content. Large variations in the image, such as bright flashes or when 'the screen goes all to white', cause the DC level to vary a lot. Some display devices don't react well to that, with a typical response being a loss of sync for a fraction of a second.

This is an issue of interaction between the video source and the display. A given source will have the problem with some displays but not with others, while a given display will have the problem with some sources but not with others. It sounds to me like your receiver is AC-coupling the output signal (which is not a bad thing in and of itself), and that your display doesn't react well to the receiver's specific implementation of that.

Unfortunately, outside of hardware modifications, I don't know of any way to fix this problem. Short of replacing any of your components, you probably need to route the video signal from your 2 sources directly to the display rather then going through the receiver. You've already seen that this fixes your problem, so that's likely your best solution.

- Dale Adams

 

[Michael_Bechtel]

Dale,

Thanks for the input. I am going to try the whole setup using another TV tonight. The remaining oddity is that I don't recall this happening until recently. In other words, I thought I had used this receiver/TV combo without the flicker for a few months, unless my eyes simply weren't that discriminating. Any ideas about this situation as something that "gradually creeps up?". I have the 3 year super plan from cicuit city on the receiver, and am tempted to return her just to test a new one.

~!Mike

 

[Dale Adams]

Mike,

I haven't heard of this type of problem just spontaneously occurring before. I suppose it's possible if the system was right on the edge of the problem happening and then something changed - electronic component drift over time, power or system grounding variations, or some other factor.

Your idea to try everything with a different display is a good one. It will verify that it's the TV losing sync and not something funky happening insider your receiver (although that seems like a bit of a stretch). A different receiver unit may in fact cause the problem to go away if your system as a whole is just on the hairy edge of the problem occurring.

- Dale Adams

 

[Andrew W]

I had this exact problem with a Toshiba SD4800 and my KP57XBR10W RPTV. I tried two of them and it was definitely a design defect of the player. My previous Sony never did it. I changed to a Panasonic RP91 and never had a problem again.

 

[Dale Adams]

Andrew,

I wouldn't assume it was a design defect in the player. It could just as easily be considered a design problem with your display being unable to track variations in the input. Some players might trigger that sensitivity and while others wouldn't. (I suspect you didn't try replacing your display, right? )

One problem that video equipment manufacturers have is that it's virtually impossible to do compatibility testing across every model that's out there in the real world. You can test 50 different displays, but there may still be one or two that don't work with your video source (and vice versa). There are enough variations in the design of video output circuits and video input circuits that it's not uncommon for a given device to work fine with 99% of equipment, but still have a problem with one or more others.

- Dale Adams

 

[RomanSohor]

This is an old thread, but I am currently having the same problem with my setup... I have an Epson Powerlite 5300 projector, and I'm running a Panasonic DVD A120 over Component cables into it.. I can't even look at the menus of Beatles Anthology... I had to switch to composite to select the DTS audio option and then switch back to Component... the new DVD player is on order from Amazon, here's hoping it will get rid of that problem!

 

[kevitra]

To add to this:

My HTPC and HD receiver work fine when plugged directly into my Mits HDTV.

When I run them through my NAD T753 I will get 'screen roll' whenever the signal becomes bright white. I am 99% certain that it is the NAD's video circuitry doing it.

I also had a Rotel HT preamp a few years ago that did the same thing. Whenever I would switch back to a direct connection to the TV the issue would go away.

 

[Leo Kerr]

Interesting.

Long before video was routinely switched through receivers, this was often a problem, and it was generally described as the television was seeing the full-white of the video signal area as too close to the vertical sync pulse level. I could always make my old monitor roll by playing my Star Wars laserdisc... all those single frame flashes would make it roll every time.

But if the TV is getting confused, then your amp might be doing some serious mucking up with the signal as it passes it through... (I've never done before/after tests on a waveform monitor... might have to try it sometime.)

Leo Kerr

 

[Dale Adams]

Long before video was routinely switched through receivers, this was often a problem, and it was generally described as the television was seeing the full-white of the video signal area as too close to the vertical sync pulse level.

The only problem with this theory is that sync is the negative-most signal excursion and white is the postive-most excursion. A full white signal could not possibly be confused with sync.

- Dale Adams

 

[Leo Kerr]

Interesting point, that. :b

The embarrising thing is that while I may have conceptually known that at the time, I DID know it when I typed it in.

Hmmm. Interesting.

Leo Kerr

 

[Brian L]

When I run them through my NAD T753 I will get 'screen roll' whenever the signal becomes bright white. I am 99% certain that it is the NAD's video circuitry doing it.

And I would say you would be 100% correct.

My 762 exhibited this issue, and my dealer was able to get an updated component video board from NAD. That cured the problem.....but (there's always a "but", isn't there?), the new board seems to have an inoperative component input 3.

So, the 762 is heading back to NAD for this, and another weird-ass problem (the front panel display occasionally wigs out and displays random, nonsense characters).

When it's running, the 762 is a very easy to use, fine sounding unit, but their QC is just not what it should be, IMHO.

BGL