Q for the hardware people: Can (these) CRTs be dangerous?

[abalone]

Now, I don't expect a super-accurate remote diagnosis... but I was wondering if I'm at risk for using these monitors.

#1 is a Fujitsu Siemens Scaleo C994 19" CRT that had gone blurry early and eventually began suffering "seizures" during which the image appeared to be torn apart horizontally, line by line shaking madly with a gentle fizzing noise... also, there was flickering pixel debris in my Amiga's "PAL Super High-Res" and "PAL Super High-Res Laced" screenmodes (1280x256 and 1280x512, respectively, + overscan area).

#2 is a Trust Precision Viewer 17" CRT that occasionally blinks into a mild cushion distortion with a couple cm disappearing underneath the plastic left & right. Sometimes it goes back to normal on its own, sometimes I turn it off and on (sometimes repeatedly).

I'm not going to use #1 anymore. It seems to be broken for good anyway. #2, though, is not a monitor I'd want to throw away just yet.

[GreyGeek]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

I doubt it.

From the Wikipedia:

Food and Drug Administration's regulations, in 21 CFR 1020, limit television receivers to 0.5 milliroentgens per hour (mR/hr) at a distance of 5 cm from any external surface.
...
The outer glass allows the light generated by the phosphor out of the monitor, but (for color tubes) it must block dangerous X-rays generated by high energy electrons impacting the inside of the CRT face. For this reason, the glass is leaded. Color tubes require significantly higher anode voltages than monochrome tubes (as high as 32,000 volts in large tubes), partly to compensate for the blockage of some electrons by the aperture mask or grille; the amount of X-rays produced increases with voltage. Because of leaded glass, other shielding, and protective circuits designed to prevent the anode voltage from rising too high in case of malfunction, the X-ray emission of modern CRTs is well within approved safety limits.

[abalone]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

Thanks! US regulations probably don't apply here but I'd expect ours to be comparable or stricter.

Oh, #2 also has a "crater" of sorts in the lower right front corner of the casing (a candle did that years ago). There isn't a hole in the plastic, just a black pit. But I don't suppose it's the plastic that keeps evil radiation contained in the first place...

Still, I was wondering if something could somehow implode or catch fire due to these malfunctions.

[GreyGeek]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

That hole in the plastic won't allow radiation to leak out because it has to get through the leaded glass first. Also, x-rays, like other forms of electromagnetic radiation follow the inverse square law. Double the distance and the radiation is 1/4th what it was.

At 10 cm the radiation would be 1/4th the strength that it had at 5 cm. At 20 cm it would be 1/16th, etc.. Twenty to 30 cm is the typical viewing distance. If the radiation were 0.5 mrem at 5cm it would be 0.031 mrem. The average daily does of radiation in the USA is about 1 mrem.

At 20 cm your CRT is 1/30th the average daily dose.

[aged hippy]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

[ ... ]
Amiga
[ ... ]

A4000 ?

[abalone]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

[ ... ]
Amiga
[ ... ]

A4000 ?

Just an A 1200 HD with a 50 Mhz 68030, 16 MB extra RAM, and OS 3.1. Reactivated it only yesterday. If it weren't so expensive I'd soup it up some... as it is, I couldn't even get the CD-ROM drive to work. Got a PCMCIA ethernet card, though I still have to install the software.

[aged hippy]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

Ahhhh, those were the days.

I had to move earlier this year, and unfortunately lots of stuff had to go...
Such is life.

[Telengard]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

Just don't try to repair them yourself.

• There are potentially hazardous materials inside CRTs, such a lead
• Some of the electrical components of CRTs can retain a large quantity of charge for a long time after being unplugged
• Breaking the CRT is a real mess, and broken glass is alway dangerous

I used CRTs for many years, and I'm pretty sure that's one of the reasons for my poor vision. I'm not blind or anything, but my vision has gotten bad enough that I almost can't drive safely except in clear weather. Don't stare into a CRT for hours on end. Take frequent breaks to let your eyes relax.

The only reason I keep CRTs any more is for my Commodore and Apple II computers.

[abalone]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

Just don't try to repair them yourself.

I doubt I'll be trying that any time soon...

It was (or is) the occasional "cushion distortion" of monitor #2 that got me a bit worried. Since it's apparently somewhat defective (or at least... I don't know... "detuned"), I was wondering if it might end up doing something less tolerable than just distort the image.

Don't stare into a CRT for hours on end.

Oops.

[Detonate]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

It might just need degaussing.

http://www.wikihow.com/Degauss-a-Computer-Monitor

[abalone]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

No, that's not it...

[abalone]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

I'm tired of half-defective 17" CRTs. I'd like an inexpensive flat screen with a resolution of 1920 × 1080 pixels or higher. I'm really inexperienced with these contraptions, though. What do I have to look out for, as a Linux- and Nvidia-user? I don't use a TV; my computer is for movie-watching, too.

Is there a possibility that POST/BIOS, tty1-6, fullscreen games or emulators will be invisible or very ugly? I don't suppose Twinview will be a problem if I want to keep an extra CRT around for such applications?

One model I saw had a DVB-T input but I have no idea what that means. Is it also a "TV tuner", ready to receive digital broadcasts, or is that just some specific connector? Er. Blah.

[aged hippy]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

When i moved, the 3cwt monitor had to go, so i got an Acer 193W, it works perfectly well on this set-up, and the 1440x900 resolution is successfully found and applied by each OS i've installed. 8)



YMMV

[abalone]

Re: Q for the hardware people: Can (these) CRTs be dangerous?

[quote=aged hippy ]
When i moved, the 3cwt monitor had to go, so i got an Acer 193W, it works perfectly well on this set-up, and the 1440x900 resolution is successfully found and applied by each OS i've installed. 8)

I think I'll have to keep a CRT anyway because there's no way my computer will play even not-so-new games at a resolution of 1920x1200 with an acceptable framerate. Unless lower-than-native resolutions look ok? Ahwell