If a CRT monitor is flickering and distorting a bit, its probably a Slightly Bad Thing. However, this morning it suddenly stopped showing anything except a bright white horizontal line across the middle of the screen, which I fear takes it into the realm of a Very Bad Thing. I've still got my old 17" monitor, so I won't be screenless, but I'm not too happy cos I only bought it about 6 weeks ago from someone at work.
Is this an issue anyone is aware of? I'm guessing that its nothing fixable for less than the price of a new monitor, but thought that there might be something I can do. There are speakers next to monitor, but I've always had them next to monitors in the past with no problems at all. The monitor also currently sits about 1m from the boiler (Landlord had some odd ideas when converting into a flat) and there may be some correlation between the distortions and the central heating kicking in, but I may be imagining it.
If its just a horizontal line showing, then it seems you've lost the vertical coils (The ones that make it go up and down). And seeing as my physics teacher told us "Don't open the back of a TV, you'll hurt yourself". I imagine same applies here. But seeing as its as good as broke, open it up, see if there's anything obviously not connected where it should be.
Speakers could cause distortion but they wouldn't make it stop working completely, how old is the monitor?
Hmm, not sure exactly but its a Mitsubishi Diamond plus93 19" CRT. Recently there has been distortion on and off when using the monitor, which usually consists of the top and bottom inch or so of the screen "bunching-up" a bit. This comes and goes, and is inconsistent in its intensity.
IIRC a CRT uses a stream of ions directed by magnets to illuminate phosphor elements on the screen. The fact that there's a white horizontal line would indicate that the magnets directing the horizontal scan works and the ones directing the vertical don't. As Pixie says, this could be due to the coils failing, or I suppose there could be a problem with the required current getting there. Either way, unless you're fairly hot on TV repair I'd say you're fucked.
Aye, I thought as much. I'd promised my old 17" monitor to a mate but hadn't actually delivered it yet, so think I'll have to rescind that offer! Fucksocks. Anyone got a 19" monitor they want to donate/sell/steal from work? I can even pick up from the North East for the next couple of weeks as I have access to a car!
yeah opening up a CRT is a bad idea. CRTs retain huge voltages (in the thousands) even if they've been off for months. it's potentially deadly in the right circumstances.
How cheap is cheapy though, given the obvious need for a decent gaming screen? I'll stick with the old 17" CRT for now, because I'd rather save up for a new GFX card than a new monitor.
IIRC a CRT uses a stream of ions directed by magnets to illuminate phosphor elements on the screen. The fact that there's a white horizontal line would indicate that the magnets directing the horizontal scan works and the ones directing the vertical don't. As Pixie says, this could be due to the coils failing, or I suppose there could be a problem with the required current getting there. Either way, unless you're fairly hot on TV repair I'd say you're fucked.
Just don't go near said coils whilst it is on, or for 5 minutes after it has been on. The electron gun (which is found where the coils are) runs at thousands of volts. Imagine licking a mains wire and then multiply that by 50.
Edit: it could also be the cable is failing to send horizontal and vertical sync info - however I'd say this is unlikely. Might be worth swapping the cable if it isn't hard wired in just in case.
amblin wrote:Oh - and it's amps that kill, not volts. Tingle yes. Murderise no.
True, but a lot of voltage being passed across a high resistance - such as the human body - will not only still be able to create the required current (3mA is it?) to stop the heart, it'll also create quite a bit of heat on the way. Best not to lick anything that says 'High Voltage' while smugly pointing out that current kills and voltage tingles
Just don't go near said coils whilst it is on, or for 5 minutes after it has been on. The electron gun (which is found where the coils are) runs at thousands of volts. Imagine licking a mains wire and then multiply that by 50.
Edit: it could also be the cable is failing to send horizontal and vertical sync info - however I'd say this is unlikely. Might be worth swapping the cable if it isn't hard wired in just in case.
Sorry, but the capacitors hold their charge for much longer than 5 minutes. Really, unless you know which bits to avoid, just don't bother with it. Like berk said, you're almost certainly not going to be able to fix it.
Also, yes it's true that voltage alone won't kill you, it's the combination of voltage and amperage that will kill you. That's why I said:
I wrote:it's potentially deadly in the right circumstances.
Oops yeah. I should've made it obvious I was kidding when I told you to open it up and fiddle around. Although if you do decide to do it, hook up a video camera showing yourself doing it.
Although the mention of the cable could be correct, as I imagine this is connected via a VGA cable, the vertical sync pins/wire could have been damaged, so try a different cable. Although this seems less likely with the interference you were talking about beforehand (As the electrons inside the Cathode Ray tube are more susceptible to interference than those in a cable).
deject wrote:Sorry, but the capacitors hold their charge for much longer than 5 minutes. Really, unless you know which bits to avoid, just don't bother with it. Like berk said, you're almost certainly not going to be able to fix it.
I'll bet you all my 5perm that it's gone (<99% of max pd) within 5 minutes.
What we need is for Lat to test this for us. Make sure your tongue is really moist.*
A completely insulated (in a vacuum) capacitor can hold charge for days - the sort used in CRT power circuitry are directly connected to a rectification and transformer circuit and will soon discharge the capacitor. Probably in under 10 seconds. There is no semiconductor diode on earth that could hold back that sort of voltage without going into avalanche. Well non that will fit in a CRT. Most you'll get is about 750V without them popping/melting. They will also have bleeder resistor on the ferrite core.
And yes it is current that kills - however I refer you to my good friend Mr Ohms. V=IR. R= your body.
up to 30mA is considered safe (well you shouldn't die).
> 6mA and you will not be in-control of you muscles. If you are gripping a wire you wont be able to let go (females 6mA, males 10mA).
> 30mA your diaphragm will be unable to inflate and deflate your lungs.
> 75mA your heart will loose its rhythm and never recover/re-stabilise.
> 4A certain death.
> 5A skin burns.
*Please don't really.
Edited to add "semiconductor" to illustrate I mean non-vacuum components found in the very first CRTs.
Last edited by Fear on March 7th, 2007, 19:02, edited 4 times in total.
Dog Pants wrote:
True, but a lot of voltage being passed across a high resistance - such as the human body - will not only still be able to create the required current (3mA is it?) to stop the heart, it'll also create quite a bit of heat on the way. Best not to lick anything that says 'High Voltage' while smugly pointing out that current kills and voltage tingles
This is all lies and i can proove it with science, behold as i -BZZZRRT- *dies*
Lateralus wrote:How cheap is cheapy though, given the obvious need for a decent gaming screen? I'll stick with the old 17" CRT for now, because I'd rather save up for a new GFX card than a new monitor.
19" widescreens, albeit only the 1440x900 ones start at around £100. Non-widescreen and smaller - 17" £90, 15" £75 and 14" £60, so the 19" seem best for real estate/£.
So, we've established that electricity can kill, sometimes.
Cheers for the pointers guys. The monitor works properly 80% of the time, flickers for ~17% and is just unusable the other 3%. I'll deal with it for as long as I can then put the 17" back up I think.
I'm definitely not opening it up and having a look, but I may drop it from a great height once it finally dies, just for shits and giggles.
Lateralus wrote:
I'm definitely not opening it up and having a look, but I may drop it from a great height once it finally dies, just for shits and giggles.
Just to let you know. Vacuum's when broken.. implode. That's fun* to watch.
*I should probably say dangerous.. err.. wear goggles?
If you're in London, I have a 21" Sony CRT that I wouldn't mind giving away.
I think it's a 21" Sony Trinitron Flat Screen Multiscan G500 CRT, but it's in the office right now and I'm not so I can't be certain.
I can even pick up from the North East for the next couple of weeks as I have access to a car!
