CurtPalme.com Home Theater Forum

[Curt Palme]

I sold an NEC XG 110 (I think)a few years ago to a customer. He's complaining about video noise in the image. Over the last couple of years (my fault in the slow turnaround), I've sent him virtually every board in the set. No change. He finally sent the set up to me. While I'm out of town for the next 2ish weeks, I did get a chance to fire it up very quickly, and didn't see what he was complaining about. I messaged him back, and he sent me the below detailed email.

Now, I know what video noise he's talking about. I've seen it on some sets, but can't remember if it was on an XG or not. Very faint scrolling horizontal lines as he describes below. I've linked him to this thread, I'm hoping that a couple of the calibrators might chime in here. I will look at the set more when I get back, and will put his original boards into the set once I return.

Comments?

Hi Curt,

If you throw up an all white image, like the internal test pattern, you can't see high frequency horizontal stuff that scrolls up or down the image and changes speed and direction depending on the content of the scene? Almost kind of like the pattern spokes on a wheel make with a stroboscopic effect, but linear. I was seeing it in any area of the image that had light imagery, like a sky, or a light colored wall, etc.

Or the 15 or so randomly spaced horizontal lines that are about a scan line high and about 10% brighter than everything else? One of which is right in the middle of where I had my image set up?

I could see this stuff in everything from internal test patterns to bluray content. I went so far as to disable every other breaker in my house except the projector, and still had the same results with the internal test pattern, or another source. Same with a new signal entry and everything reset.

It concerns me that everyone else I pointed these things out to could see them once I showed them what to look for, but you don't seem to see them. Perhaps you do see what I'm seeing, but you consider it to be in spec? If you truly don't see any of what I sent the set back for, I'm not sure what to do. I can't see how it could have anything to do with my power, but I'm never going to be happy with the image if the noise is going to persist and I don't know what else could be causing it to only be seen here.

My expectations of what I should see on an all white image is a smooth white image on screen or looking at the tube face, with no variation or modulation. I don't know if I can see the noise looking without the lenses, but can def see it in on all tubes looking into the lenses, or on screen. The only thing I feel like I should see is faint separation between scan lines, but I haven't really seen that because I've not been able to get the beam convergence sharp enough. I had better luck with red, but as you pointed out, green is soft and nothing I tried seemed to help. The noise isn't something the average person sees without me pointing it out, but everyone sees it once I point it out, especially standing closer to the 8' screen.

Perhaps my tolerance is too low, I work with digital projection and broadcast quality hd video gear in my day job but on the other hand, I never saw either of these PQ issues with the much less expensive ECP projector I had previously.

So if you aren't seeing what I'm taking about, I don't know what to do. Obviously, I'm sure you could see what I'm referring to, if it were happening there. I just don't see how it could be location specific.

[Curt Palme]

I sold an NEC XG 110 (I think)a few years ago to a customer. He's complaining about video noise in the image. Over the last couple of years (my fault in the slow turnaround), I've sent him virtually every board in the set. No change. He finally sent the set up to me. While I'm out of town for the next 2ish weeks, I did get a chance to fire it up very quickly, and didn't see what he was complaining about. I messaged him back, and he sent me the below detailed email.

Now, I know what video noise he's talking about. I've seen it on some sets, but can't remember if it was on an XG or not. Very faint scrolling horizontal lines as he describes below. I've linked him to this thread, I'm hoping that a couple of the calibrators might chime in here. I will look at the set more when I get back, and will put his original boards into the set once I return.

Comments?

Hi Curt,

If you throw up an all white image, like the internal test pattern, you can't see high frequency horizontal stuff that scrolls up or down the image and changes speed and direction depending on the content of the scene? Almost kind of like the pattern spokes on a wheel make with a stroboscopic effect, but linear. I was seeing it in any area of the image that had light imagery, like a sky, or a light colored wall, etc.

Or the 15 or so randomly spaced horizontal lines that are about a scan line high and about 10% brighter than everything else? One of which is right in the middle of where I had my image set up?

I could see this stuff in everything from internal test patterns to bluray content. I went so far as to disable every other breaker in my house except the projector, and still had the same results with the internal test pattern, or another source. Same with a new signal entry and everything reset.

It concerns me that everyone else I pointed these things out to could see them once I showed them what to look for, but you don't seem to see them. Perhaps you do see what I'm seeing, but you consider it to be in spec? If you truly don't see any of what I sent the set back for, I'm not sure what to do. I can't see how it could have anything to do with my power, but I'm never going to be happy with the image if the noise is going to persist and I don't know what else could be causing it to only be seen here.

My expectations of what I should see on an all white image is a smooth white image on screen or looking at the tube face, with no variation or modulation. I don't know if I can see the noise looking without the lenses, but can def see it in on all tubes looking into the lenses, or on screen. The only thing I feel like I should see is faint separation between scan lines, but I haven't really seen that because I've not been able to get the beam convergence sharp enough. I had better luck with red, but as you pointed out, green is soft and nothing I tried seemed to help. The noise isn't something the average person sees without me pointing it out, but everyone sees it once I point it out, especially standing closer to the 8' screen.

Perhaps my tolerance is too low, I work with digital projection and broadcast quality hd video gear in my day job but on the other hand, I never saw either of these PQ issues with the much less expensive ECP projector I had previously.

So if you aren't seeing what I'm taking about, I don't know what to do. Obviously, I'm sure you could see what I'm referring to, if it were happening there. I just don't see how it could be location specific.

[CasetheCorvetteman]

Have you tested another power supply?

[Curt Palme]

yup.

[Curt Palme]

yup.

[Nashou66]

I assume you sent him new neck boards to try?

Nashou

[Curt Palme]

I've got the set here now. I don't think I changed the neck boards, but I've never had one fail other than a really obvious failure of very low or no output at all. I will run the heck out of the beast before I send it back.

[Curt Palme]

I've got the set here now. I don't think I changed the neck boards, but I've never had one fail other than a really obvious failure of very low or no output at all. I will run the heck out of the beast before I send it back.

[CasetheCorvetteman]

My RUNCO 991 does this as well but i havent seen it on all signals, and its so minor no one else can see it but me.

I remember my Panasonic GAOO rear projection TV did something very simular too.

[cygnus23]

Hi there,

The XG110 under discussion is mine. I saw the noise in all three tubes, is it possible for all of them to have the exact same issue? Doesn't seem likely, which is why I'm guessing Curt didn't send me replacements. The other thing I would mention, is that very once in a while, I would hear a quiet snapping noise (maybe once in 20 hrs.) and sometimes (if I were sitting in the back row, where the PJ is just in my vertical peripheral vision, I could see what I believe to be a brief flash, coming through the vents by the green tube. No idea if this is normal, or if it has anything to do with the noise, but I thought I should bring it up.

The issue isn't bad enough to take me out of a movie I've never seen, but if I'm watching something I know well, and am looking around the image for new content, it's obvious. As it's also obvious when watching something like sports or anything shot outdoors, in parts of the image above 40-50 IRE.

And yes, I did purchase the set from Curt a while back, and unfortunately had it in storage for about 5 years while I completed my HT. Only after hooking it up for more than a couple hours to check placement, etc. did I notice some problems. Not Curt's fault that it in storage so long without me doing a critical look at it, just unfortunate that I don't know if it was a problem that could have developed over time, or whether it was an issue from the start.

Thanks in advance for any insight anyone might have, and please let me know if what I'm seeing is normal, or not.

I've still not watched the movie I thought was going to be my opening night screening, because I waited so long for the theater to be done, that I didn't want to watch the movie with the PJ in its current state. Not that I haven't watched anything in the 2 years since I've had it running, I certainly have. But I'd just like to make it right.

Bryan

[cygnus23]

[gjaky]

I had some similar issue with my first PG xtra, however in that case it wasn't dependent from video content, one faint (only on red) line randomly appeared on screen. It was the DCPC board, not sure if your peoblem is similar, but tought I share.

[CasetheCorvetteman]

I havent looked on the white paterns so i dont know, but its in all colours, and only on bright scenes. Doubt itll be all 3 neck boards, but it is certainly the same on all 3 tubes.

[CasetheCorvetteman]

I know it certainly doesnt do it on either 240p, 480i or 576i from my game consoles. I never use compost video so i dont know if its there too.

[macgyver655]

Unfortunately I have seen this before. It was about the third or 4th projector I owned. I also tried swapping probably every board in it and even changed some parts. There was absolutely no affect on the distortion no matter what was changed. I finally moved it to a different room in the house and it was gone. Oh, I also tried shutting down the house power. My guess as to what was causing it is really out there so I'm not going to post it, lol.

[CasetheCorvetteman]

In my case i would think it may be the step down trans im using, im not sure if the fact the machine is rated to run on 60Hz and im feeding it 50Hz will have any impact

[RogerH]

I have experienced a problem which may be similar to what you describe, both with my XG and with other projectors.

I would see very, very faint horizontal bands (like faint venetian blinds) that would roll vertically in one direction, slow, stop, and reverse. Sometimes they would speed up to the point that they were undetectable until they again slowed, stopped, and reversed. In my particular case I was seeing maybe 20 to 40 of these intensity modulations from top to bottom, although they were nearly impossible to count accurately.

And here too, most people would not see them until I would actually point them out (when they slowed down) by running my hand up or down the screen at the roll rate. I think eventually people's eyes would follow the hand, and then they would lock on and see the rolling bars. Some people could never see them.

I don't know if what I saw is what you are describing. Although it is entirely possible that this is internally generated noise, in my case it was something external and not generated within my house. It was also present on my internal test patterns.

A few things you could do that would help isolate the problem:

1) If you have the capability to change your source or use a video processor to run a different vertical frequency, try that. I had a problem disappear if I ran 72Hz instead of 60Hz.

2) Try disconnecting EVERY cable from the projector except for the power, and observe the internal patterns. You must have only one connection to the projector, and that is to power it up. There should be no other conduction paths to the projector (metal mounts are OK as long as they don't contact any conductive structures). Multiple connections to the projector form loop antennas that, in a high ambient RF noise environment, can generate very small noise voltages than can end up in the wrong places inside. Common-mode noise can get into a projector through any type connector, whether analog, digital, or power. Breaking potential antenna loops can eliminate most (but not all) sources of common-mode noise.

3) If the noise is still visible, try turning off everything in the house as you did before. Try to think about and disable stealth RF noise sources that may still be running with your breakers off (battery powered digital devices, UPS backups, etc), or any other devices on the projector breaker.

4) You say that you are running through a step-down transformer. Do you know if this is an isolation transformer or an autotransformer, or something else?

Ruling out external RF noise sources can be trickier than you might think, but it's an important step because you first need to definitively isolate the problem to either your projector or your environment/cabling.

[cygnus23]

[Jeremy112]

Damn, I was really hoping the issue he had with his XG was also the issue I was having with mine. A real bummer.

I can say from using my XG that I have not experienced this issue. But from reading this discussion, it sounds like a signal issue, could be bad sync or a cable that works but itsnt up to full spec, seen that plenty of times... but since curt has it and its still doing it.... im betting it is something in the video input circuit.

Unfortunately I have not been able to resolve the ultra bright raster issue my NEC XG exhibits. (CURT) I did try swapping the neck boards, and it did not have any affect. I did also notice the bright raster on the green tube, but it isn't as bright so its not noticable on the screen...

For some reason it has something to do with the blanking I think, because the blanking bars are a bluish gray and not black at all, and when I mess with blanking I can make the visible on screen raster get smaller, but not go away...

Sorry for hijacking the thread! But I've asked about this problem many times and never got a solution. Anyway back to the OPs topic.

[RogerH]

Back to the rolling bars problem...

Somehow, somewhere, you may be getting a low level AC signal into your common video that is on the order of the number of horizontal bars that you see onscreen at any given instant (counting from top to bottom) multiplied times the vertical frequency.

The fact that you have some bright (randomly spaced but stationary?) scan lines is also really weird, but maybe that is telling you something and is pointing to a common problem. On the one hand, subtle, vertically-rolling bars seems to point to something leaking into the video that is a close (but not phase coherent) multiple of the vertical frequency. But fixed brightness variations that do not roll (your bright scan lines) seem to point to some type of noise leakage that IS synchronized to the vertical sweep, so that it bumps the brightness of the same line every time.

Were your bright lines bright over the full horizontal sweep? That would be tough to explain. Or did they appear brighter only on one side of the screen?

It's a longshot, but since there is so much RF noise of so many different frequencies swimming around in a projector chassis, did you try the usual step of reseating of all of the cards and connectors? It's not impossible that some board or connector grounds are a little less than ideal, increasing the susceptibility of the video chain to noise pickup, or possibly increasing the emissions from other cards or the PSU.

[CasetheCorvetteman]

This is not my problem, my moving bars stay exactly the same. My 9PG didnt do this in the same spot.

Jeremy, press the KELVIN button and turn down the low end, its too high if youre seeing the raster lit up.

[cygnus23]

[CasetheCorvetteman]

10% is a hell of a big increase in brightness, it its that much, it should be very obvious.