Sony monitor interference mystery

Bring another computer into your house and try the monitor with it. I'll bet you don't see the problem.

This is classic moire, and can be caused by anything from running at too high a resolution/refresh rate to (in your case) video circuitry that's placed too close to other components in a laptop or desktop.

Well, I have tried it on another PC, and on my laptop. Both at the lowest resolution and refresh rates possible. I will try it in a 3rd PC next week at work, but surely it shouldn't be that prevalent a problem inside this many PC's?!

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It looks like Moray effect from the aperture grill (lines) beating against the scan lines. Does the effect vary when you move the centring, height, or other scan parameters?

If the beam focus is slightly off its proper setting, it is possible to have these lines emphasized. The focus performance can change with the aging of the CRT, or something has changed in the focus supply from the HV multiplier.

As for black shadows on the edges of highlighted lines, this can be caused by capacitors that have drifted off value, or the CRT is going a little weak. The shadows are caused by the effective video low frequency response being rolled off a little.

--

JANA _____

SCC-L45B-A SV-3614(U) J505279

The issue is a shimmering rainbow effect on vertical black lines. I first noticed it around black text on white backgrounds, where there would be sections of text with red, green, or bluish shadows around them. I've since found a test pattern program (ntest.exe) that will put solid vertical lines on the screen (alternating light and dark), which shows the pattern quite vividly. It's apparent in any resolution and refresh rate.

I have two pictures at this URL:

I took the monitor to a local Sony-authorized shop. Before I left it with them, I had them run the same test pattern using the same program, and the image over there was perfectly clean looking! We tried to increase the refresh rates/resolution, but he was having trouble getting his computer to cooperate so I left it with him to try and figure out. Today he called to say he'd run it up to 1600x1200 at 85 hz, and not seen any signs of what I described. He suggested I try powering the monitor with a UPS, so I picked up a UPS from work, and brought the monitor home.

I connected my laptop (running on battery) to the monitor, which was plugged into the UPS (which was running totally on battery, unplugged from the wall), and the interference was there. I moved it around the house, upstairs and down, and got no change. I even hauled it out to the car, with the UPS, and drove around the block with it running, all with no change! I did notice however that my signal light had an effect on the pattern, causing it to shift slightly every time the lights came on. Also, when I rotate the screen left or right, every x number degrees of rotation will cause the pattern to jump in one direction or another.

Does this sound like some nasty EM field in my neighborhood? I can't think of anything else that would cause this. My only other idea was to take the monitor into work when I'm off vacation next week, and try it there. We are not too far from the repair shop in the same industrial park Other than that I am out of ideas!

Anybody have any other thoughts as to what the problem might be?

FWIW. I have another monitor, a 19" Viewsonic, that always has had a slight shake at the edges of the screen. Similar in frequency to the shimmering of the interference on the Sony. I ran the test pattern on this monitor, and there is a similar effect, but not nearly as intense... and mosly limited to edge of the screen. Until now I never gave it much though, it was a refurbished monitor, but now it seems like it could be related.

Maybe the Sony is just particularly sensitive to EM fields?

or

It does, but it also varies if I swivel the monitor left or right. This makes me think it's something external influencing the beam.

have

But the effect was totally gone when at the shop...

There are no black shadows around anything. There *are* shadows of red, green, or blue depending on which section of the screen you are looking. They appear around black text on a white background, and they correspond to the pattern mentioned above. I'm sure it's just the same problem but only visible where black borders on white.

You have tried all the user-accessible adjustments on the monitor, right?

FWIW, about ten years ago I bought a new computer with a 17" Trinitron monitor. In the setup section, the user manual mentioned that if you couldn't get the picture adjusted exactly the way you wanted it, it might be due to the Earth's magnetic field. It suggested placing the monitor with the screen facing east (I think) to see if that helped any. This somewhat agrees with your observation that the display changes when you swivel the monitor.

You might try moving the monitor to other places in your home. At first, face it the same direction as it usually faces, then try pointing it different directions. If you still get the interference in its usual position, which then changes or goes away in other positions, then it may well be because of the Earth's magnetic field. If the interference goes away completely in a certain location, figure out what's different about that location.

If you're in an apartment, check that your neighbors haven't started a motor rewinding shop or mail-order magnet supply house out of their apartments.

Matt Roberds

Yeah, I moved it all around the house; and tried it facing all different directions... I even took it around the block in the car. A friend of mine wondered if there was a HAM radio operator in the area, which I guess is possible...

Heheh yeah I'm in my own house but I wouldn't be surprised if someone's got a particle accelerator or something in their basement... that would explain the silverware sticking to my forehead all the time ;)

I'm taking it to work next week so that will be the real test.

try a different scan rate..

why does it worek ok at the Sony shop..

what is dfferent there?

Do you have an AM radio station near your house?

You see the intereference in your car? What if you drive to the Sony shop?

Mark

That is the question that needs to be asked. The picture looks like either moire interference caused by too high of scan rate for the aperature grill in the picture tube or a video bandwidth problem.

If it really does work perfect on the test setup at the service shop, then it stands to reason that it is some part of the equipment that did not go to the shop. Did the video cable go with the monitor? Did the computer go with the monitor?

I am guessing that it is an el-cheapo video card problem where the card has a bandwidth problem or other issue.

JM wrote: A friend of mine

Most HAM Radio operators cause no interference to anyone's electronics in their neighborhood. We follow strict guidelines in regards to RFI and try to maintain our equipment to not cause anyone problems. Also the problems you describe don't sound like they are being caused by RF interference.

KB2ZWO

It's the same regardless of scan rate.

Wish I knew.

Well, I'll be taking it to work next week, which is fairly close to the shop. If it does it there, then maybe I'll drive to the shop with it hooked up in the car and see if it continues to do it when I get there. If so it'll be pretty hard for them to deny its existence :)

Well I'm fairly confident I'll know much better once I get the monitor away from this area and, if necessary, in my car outside the repair shop.

The video cable did, the computer did not, but the video card is a Leadtek Geforce 6600, and I had the same symptoms with a Geforce 4 ti 4200 before that. The shop computer was a Geforce FX 5200 or something like that.

Also, the problem exists when my laptop is connected, and when a third PC is connected. My desktop runs a 450 watt PSU (with only one hard drive, 1 gig of RAM and a CPU to power) and I have an Asus A7N8X motherboard. Shouldn't be anything there that would cause problems.

That was my thought, if that wasn't the case then there would be all kinds of reports of interference from HAM radios and what not.

I agree, to me it looks more like an EM field in the area. Especially considering how the pattern changes as I rotate the monitor...

I'm starting to wonder if maybe *I* am giving off a magnetic field...

I ask agaqin...is there an AM radio station transmitter in your area...i.e big towers?

Mark

Not in my immediate area, no.. I'm in the suburbs so there's nothing like that too close. A few cell towers within a 2-3 km radius I would say, but that's pretty common anywhere these days I'm sure.

1. Possibly the aperature grill is miasaligned due to the unit falling.
2. Do you live near a medical facility with an MRI machine?
3. Magnetic field due to wir>I've got a bit of a mystery on my hands with my Sony 21" CPD-G520P monitor.

On Thu, 18 Aug 2005 17:34:25 GMT, "JM" put finger to keyboard and composed:

Smack the face of the CRT with your hand. Does the pattern vibrate? If so, then this would confirm that your problem is related to the aperture grill.

- Franc Zabkar

No change at all if I smack on the case, or directly on the screen (as hard as I felt comfortable doing).

What is around the monitor? Any other electrical equipment? Maybe a nearby tv set or other device?

Well there is a small tv about 4 feet away.. and my pc tower next to the monitor,but as I said I've moved it all around the house and driven it around the block... all with no appreciable change in the problem.