teh_Foxx0rz wrote on 2023-08-02, 20:41:

I picked up a lovely Iiyama VisionMaster 450 a little while ago. It's very nice to have a CRT at last, I can enjoy seamless old […]
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I picked up a lovely Iiyama VisionMaster 450 a little while ago. It's very nice to have a CRT at last, I can enjoy seamless old PC/Mac gaming and even my Dreamcast on there too.

However, there are some things with it that I'm not sure about.

Firstly, while lower resolutions look good, up to about 1024x768, higher resolutions exhibit some very obvious "echoing" to the picture; impressions of elements repeat towards the right of the element, shown in the attached photo. There's also a slight "shiver" to the picture, especially towards the bottom edge. I've tried adjusting every setting, and using different VGA cables or computers, but none of this affected these issues.

Secondly, I've got these classic Cambridge Soundworks FPS1000 PC speakers. Everything should suggest that these would be shielded, however, they're still causing distortion in the CRT picture when I move them around. It's not usually so obvious as in the picture below where I point their back at the CRT, but there's still some change when they're near, and I get the impression that the effect of a magnetic field is much more pronounced than what you can see. Are these safe to keep near the monitor...? And how come they're causing a problem, if they are?

Softness or echo/shadow in the image may result from poor quality video card output (analog tech such as CRTs is where the quality of the components really did still matter). This is why Matrox was praised for image quality - the image would remain sharp and consistent even at high resolutions. With the nVidia/ATi-cards, there was a lot more variance depending on the partner who put the actual board together.

If you're certain the video card has stellar output, you may next want to look into the quality and shielding of the cable connecting your monitor to the video card. On cheaper monitors this is fixed and cannot be swapped, so you better hope yours is good and in prime condition. I ruined a CRT in my youth by pushing my PC's tower case too close to the wall. The resulting bend in the VGA cable made the image on the monitor very blurry with several shadows going thru it - and the damage was permanent, I had to swap the whole thing.

Finally, there is the monitor itself. Depending on the condition of the internal circuitry (and the cable, if it is fixed), this may be as good as you get. I haven't read the reviews for your specific tube, but the cheap ones really had no business being used at anything above 1024x768 a lot of the time, even if they were 19"!

-- oh and your speakers are clearly not properly shielded. Keep those things away from the monitor so you don't do permanent damage to it.

1. Which GPU do you have? GPUs on MOBO are really bad in terms of VGA quality.
2. Keep away magnetic objects, that's the problem.

Yeah, I tracked down a set of those Cambridge Soundworks speakers because I had a set when I was younger and I thought they would be perfect to pair with my CRT. I was immediately disappointed to find out they were distorting the image and clearly aren't properly shielded.

It has me baffled, because I don't remember it being a problem for me back in the day, and I'm fairly certain I would have still been using a CRT at the time I had those speakers.

As mentioned, I've tried several different computers and thus several different graphics cards. I've tried a PC with a Geforce FX 5700, another with a Voodoo 3 3500, and a Powermac G3 Blue & White (thus some ATI Rage card or whatever is standard for those), and those all have flawlessly sharp quality through my OSSC in another room at the same settings, and also directly to the LCD display I had on this desk before getting this CRT. This CRT fortunately does have a detachable VGA cable and so I've also tried two different VGA cables, one of which I also use with my OSSC, and it's never shown any problems on there.

At this point, I don't think I see any room for it to be anything other than something to do with the CRT itself.
I couldn't find much information about this specific model, but the one review I did find and other things I've heard about Iiyama suggested that they're a respectable brand.

And yeah, like Danieljm says, you'd have thought these speakers would have been designed appropriately for use with CRTs, and after I bought them, there was even a video that came out by LGR where he uses them with fold-out arms for rear speakers, where he mentions them as being shielded. Of course he's no authority, but I'd expect someone like him to have the experience and connections to actually know something like this, as well as the personal impetus to get it right.
The only thing I can think of then is that perhaps there were some of this model that had shielding and some that didn't. I have no idea of my own though.
I have sadly removed them from next to the CRT now, though. Any idea how long they have to be near a CRT for them to cause damage...?

Shielded speakers have a steel cup placed over the magnet ring with some gap around the speaker's cone frame. You could duplicate that using cut in half food cans glued on or stuck on with double sided adhesive, they're steel.

Cheers,

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says

1All five
2speakers are magnetically shielded.

Could something have gotten loose inside one of the speakers ?

Do they all cause distorsions on the the CRT monitor's screen ?

Magnetically shielded speakers can still cause some CRT interference, the shielding on cheap plastic speakers can't be too thick or it will add to weight so much it'll affect shipping costs (and production materials). The field of the permanent magnet is "shorted" by the iron sheet around it but not down to zero - every centimeter counts in such cases. The same speaker might not cause any interference when it's moved 5-10cm away from the tube, and obviously the internal EM shielding inside the monitor (or lack of it) will also affect the outcome. The shield material inside the speaker might be subpar or it got itelf slightly magnetized by now.

If the speakers can't be moved away from the monitor then at least don't move them around anymore and try running manual CRT degaussing a few times (do note this heats up the coil, don't repeat it without pauses as not all monitors are properly designed to withstand such frequent use - a minute or two between "shots" should be enough). If there is still interference (colors, brightness or focus affected near the speaker) then the speakers must be moved away or replaced.

Ghosting, from my experience, is usually down to poor quality cable between card and monitor. Sometimes the card itself is really bad - I've seen some cheap cards, usually based on S3 chips, stripped down of everything that could be stripped like all the output LC filters and even most power filtering caps.

In my extremely limited experience, shielded speakers were only really shielded on the outside edges and not front to back: on my family’s second computer (first multimedia PC) the speakers didn’t impact the CRT as long as there were on the sides and not slightly in front.

Is this possibly your issue?

So, I waved them around the screen a bit more, even holding them sideways, and they have a huge impact on the monitor. I compared them against the slightly later black Cambridge Soundworks speakers I still use on my main PC, and yeah, these small beige ones really don't seem to have adequate shielding, as far as I'm concerned. The black ones still produced some distortion when held up close but it was just faint darker patches, and didn't feel like something was going on that shouldn't be.

I also took a closer picture of the "ghosting" issue I'm getting. This is with a completely different computer and VGA cable than I used in the first picture, and it's still having the issue.

teh_Foxx0rz wrote on 2023-08-09, 17:59:

I also took a closer picture of the "ghosting" issue I'm getting. This is with a completely different computer and VGA cable than I used in the first picture, and it's still having the issue.

Different doesn't mean good. A decent VGA cable should be some 9-10 mm in diameter, reason being the RGB signals are each a separate mini-coax inside the cable (which has its own shield as well). Anything thinner will just use normal wires and at higher frequencies (= higher resolutions) the reflections caused by complete lack of impedance match show as ghosting.

Some cheap SVGAs can also have next to none filtering and impedance matching network on the output, and that also will cause ghosting. Having both poor cable and subpar SVGA is usually so visible that even mouse cursor has 1 or 2 friends following it.

They do have some shielding, but I think specifically enough to be placed relatively close next to the monitor, not in front of it. Do you see any distortion or dark patches if you place them next to the monitor at a normal distance (eg. not right up against it)?

Deunan wrote on 2023-08-09, 18:19:

teh_Foxx0rz wrote on 2023-08-09, 17:59:

I also took a closer picture of the "ghosting" issue I'm getting. This is with a completely different computer and VGA cable than I used in the first picture, and it's still having the issue.

Different doesn't mean good. A decent VGA cable should be some 9-10 mm in diameter, reason being the RGB signals are each a separate mini-coax inside the cable (which has its own shield as well). Anything thinner will just use normal wires and at higher frequencies (= higher resolutions) the reflections caused by complete lack of impedance match show as ghosting.

Some cheap SVGAs can also have next to none filtering and impedance matching network on the output, and that also will cause ghosting. Having both poor cable and subpar SVGA is usually so visible that even mouse cursor has 1 or 2 friends following it.

this

Is there any way I can identify a more suitable cable than something like this then? I have several similar ones. They're all clearly from the era and about 1cm in diameter. As I mentioned in a previous post, they don't seem to have a problem when going to my OSSC with the same hardware. And thinner, seemingly cheaper (or at least more modern) cables have been perfect with that as well.

Daniël Oosterhuis wrote on 2023-08-09, 20:53:

They do have some shielding, but I think specifically enough to be placed relatively close next to the monitor, not in front of it. Do you see any distortion or dark patches if you place them next to the monitor at a normal distance (eg. not right up against it)?

I could find this understandable...if the manual didn't specifically illustrate sticking them directly to the sides of the monitor. Perhaps they weren't designed with that in mind but it went in the manual anyway, but that would still leave them being less shielded than is appropriate for their described use.

It seemed to be something like 15~20cm away before I stopped noticing dark patches or distortion ripples while moving them.

maxtherabbit wrote on 2023-08-10, 13:27:

Deunan wrote on 2023-08-09, 18:19:

teh_Foxx0rz wrote on 2023-08-09, 17:59:

I also took a closer picture of the "ghosting" issue I'm getting. This is with a completely different computer and VGA cable than I used in the first picture, and it's still having the issue.

Different doesn't mean good. A decent VGA cable should be some 9-10 mm in diameter, reason being the RGB signals are each a separate mini-coax inside the cable (which has its own shield as well). Anything thinner will just use normal wires and at higher frequencies (= higher resolutions) the reflections caused by complete lack of impedance match show as ghosting.

Some cheap SVGAs can also have next to none filtering and impedance matching network on the output, and that also will cause ghosting. Having both poor cable and subpar SVGA is usually so visible that even mouse cursor has 1 or 2 friends following it.

this

I have been down that rabbit hole before: Re: VGA Capture Thread

darry wrote on 2023-08-12, 03:19:

I have been down that rabbit hole before: Re: VGA Capture Thread

These cables aren't giving me ghosting when used with the OSSC like you're describing. Surely that would mean they aren't the problem?

Here's a direct capture from my Voodoo 3 3500 TV. I tried this with my CRT and had the same noticeable ghosting issue as in the previous photos. The other systems and graphics cards I've used in the previous photos of my CRT to show the ghosting have looked just as sharp through my OSSC, through the same cable. Maybe there's some analogue imperfection in this screenshot when viewed up close but not enough to matter for my needs, and certainly not as bad as I'm seeing on my CRT.

teh_Foxx0rz wrote on 2023-08-12, 17:35:

darry wrote on 2023-08-12, 03:19:

I have been down that rabbit hole before: Re: VGA Capture Thread

These cables aren't giving me ghosting when used with the OSSC like you're describing. Surely that would mean they aren't the problem?

Here's a direct capture from my Voodoo 3 3500 TV. I tried this with my CRT and had the same noticeable ghosting issue as in the previous photos. The other systems and graphics cards I've used in the previous photos of my CRT to show the ghosting have looked just as sharp through my OSSC, through the same cable. Maybe there's some analogue imperfection in this screenshot when viewed up close but not enough to matter for my needs, and certainly not as bad as I'm seeing on my CRT.

Indeed, there is some ghosting, but very little [1], compared the what is seen on the monitor.

My guess is that something is likely very off with the impedance on the connector or wiring inside the monitor .

Two things you can safely try (without opening the monitor) are

a) Deoxit or another contact cleaner on the 15-pin D-SUB connector on the monitor (which I assume is the one you are using to connect the VGA card)

b) a high quality 15-pin D-SUB to BNC RGBHV cable to connect the VGA card to monitor's BNC input as whatever issue that could be affecting the regular VGA input MIGHT not be affecting the BNC one .

[1]