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Ominous Ticking from Monitor
My monitor (a DEC 21" CRT, older than dirt) has started to give sharp,
static-discharge type audible ticks, which are accompanied by short distortions of picture and dimming. The picture distortion lasts for a refresh cycle, the dimming can take a few cycles to disappear. When I power off the screen, I hear a number of these ticks happening, one after the other, tapering off. Where do I begin to look for a solution? Google has not been much help. Thanks! |
#2
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Ominous Ticking from Monitor
I.C. Koets wrote:
My monitor (a DEC 21" CRT, older than dirt) has started to give sharp, static-discharge type audible ticks, which are accompanied by short distortions of picture and dimming. The picture distortion lasts for a refresh cycle, the dimming can take a few cycles to disappear. When I power off the screen, I hear a number of these ticks happening, one after the other, tapering off. Where do I begin to look for a solution? Google has not been much help. Thanks! That's a hi-voltage breakdown My advice is not to fool with it as the high-voltage is dangerous. OK now that you've insisted to ignore caution you will need to open the monitor and observe where it's arcing {turning the lights off in the room will help} Now with the monitor off you can spray down the area with corona dope or other suitable insulation. NOTE: even with the power off and the unit unplugged...hi-voltage will be retained!!!! So you should not really fool with it |
#3
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Ominous Ticking from Monitor
On Thu, 28 Jan 2010 21:01:30 -0600, philo wrote:
I.C. Koets wrote: My monitor (a DEC 21" CRT, older than dirt) has started to give sharp, static-discharge type audible ticks, which are accompanied by short distortions of picture and dimming. The picture distortion lasts for a refresh cycle, the dimming can take a few cycles to disappear. When I power off the screen, I hear a number of these ticks happening, one after the other, tapering off. Where do I begin to look for a solution? Google has not been much help. Thanks! That's a hi-voltage breakdown Exactly!!!! don't touch anything.. I hope he will not follow your suggestions, while I know you want to help... hi-voltage can kill! Bring the monitor to a qualified lab, if the reparation cost is too much, just buy a new one. New monitors are really cheap considering the models of years ago and you can have a quality replacement without spending too much. I suggest to just buy a new monitor... -- http://shop-for-computer.com - Best Pc Deals, Refurbished Deals http://shop-for-clothes.com - Shoes, Handbags, Shirts, Coats http://shop-for-car.com - Huge Car Deals, Auto Parts |
#4
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Ominous Ticking from Monitor
"I.C. Koets" wrote in message
l... Ominous ticking ... its a bomb! (joke - sorry, couldn't resist!) My monitor (a DEC 21" CRT, older than dirt) has started to give sharp, static-discharge type audible ticks, which are accompanied by short distortions of picture and dimming. The picture distortion lasts for a refresh cycle, the dimming can take a few cycles to disappear. When I power off the screen, I hear a number of these ticks happening, one after the other, tapering off. Where do I begin to look for a solution? Google has not been much help. Whilst I'm sure with the right know-how you might be able to fix it, unless you really know what you are doing its probably not particularly safe to poke around the insides of a CRT monitor given that there are some rather nasty high voltages in there. Time to buy a new monitor. You'll find with an LCD flat-screen monitor you will be able to reclaim much of the desk space that your old CRT was taking up. -- Brian Cryer www.cryer.co.uk/brian |
#5
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Ominous Ticking from Monitor
I.C. Koets wrote:
My monitor (a DEC 21" CRT, older than dirt) has started to give sharp, static-discharge type audible ticks, which are accompanied by short distortions of picture and dimming. The picture distortion lasts for a refresh cycle, the dimming can take a few cycles to disappear. When I power off the screen, I hear a number of these ticks happening, one after the other, tapering off. Where do I begin to look for a solution? Google has not been much help. Thanks! CRTs, especially old ones, should be recycled at this point. They're not worth trying to save when they go out. If you take it to a repair guy, you'll probably wind up paying more to get it fixed than buying an LCD would cost you. If you're low bucks, you might consider buying a refurb at http://www.Geeks.com. Otherwise, LCDs have come down in price so much in recent years that it's a very affordable choice. And your eyes will thank you because thanks to LCD's latency, there is no flickering like with a CRT (pass your hand rapidly back and forth in front of a CRT, then an LCD, and you'll see what I mean.) Working on a CRT, as others in this thread have warned you, can get you killed if you touch a high voltage capacitor for instance. Not only that, but if you actually succeed in turning on a CRT with it's cover off, you will be exposing yourself to dangerous radiation. Seriously. -- John Corliss |
#6
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Ominous Ticking from Monitor
I.C. Koets wrote:
My monitor (a DEC 21" CRT, older than dirt) has started to give sharp, static-discharge type audible ticks, which are accompanied by short distortions of picture and dimming. The picture distortion lasts for a refresh cycle, the dimming can take a few cycles to disappear. When I power off the screen, I hear a number of these ticks happening, one after the other, tapering off. Where do I begin to look for a solution? Google has not been much help. Thanks! If you want a safe experiment to try, try changing the resolution settings to the monitor. I have a Trinitron, and it started arcing when the resolution was set to 1280x1024 @ 75Hz. If I changed the resolution setting of the video card to 1024x768 @ 60Hz, the arcing would stop. The monitor compensates for the way it is run, and the operating voltage seems to change as a function of the resolution and refresh rates used. I even noticed the monitor ran cooler, with the lower resolution setting. You can try that as a workaround, until you can get another monitor. A TV repair man would know how to fix that problem, but the real problem for him, would be getting parts. Mine needs a new flyback, but that ain't gonna happen. My CRT languishes in the basement now, with an LCD to take its place. By me posting this link, this is not an invitation to go inside the monitor. This is just so you know what a flyback is. Really, they should stick a picture of a skull and crossbones on the thing, so you'll stay away from it :-) The rubber boot on the red wire, is to prevent corona. http://en.wikipedia.org/wiki/Flyback_transformer I've actually used one of those, to build my own high voltage power supply. The most remarkable thing about that, is I've never managed to give myself a shock :-) :-) Talk about lucky... Paul |
#7
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Ominous Ticking from Monitor
Kyle wrote:
On Thu, 28 Jan 2010 21:01:30 -0600, philo wrote: I.C. Koets wrote: My monitor (a DEC 21" CRT, older than dirt) has started to give sharp, static-discharge type audible ticks, which are accompanied by short distortions of picture and dimming. The picture distortion lasts for a refresh cycle, the dimming can take a few cycles to disappear. When I power off the screen, I hear a number of these ticks happening, one after the other, tapering off. Where do I begin to look for a solution? Google has not been much help. Thanks! That's a hi-voltage breakdown Exactly!!!! don't touch anything.. I hope he will not follow your suggestions, while I know you want to help... hi-voltage can kill! Bring the monitor to a qualified lab, if the reparation cost is too much, just buy a new one. New monitors are really cheap considering the models of years ago and you can have a quality replacement without spending too much. I suggest to just buy a new monitor... -- http://shop-for-computer.com - Best Pc Deals, Refurbished Deals http://shop-for-clothes.com - Shoes, Handbags, Shirts, Coats http://shop-for-car.com - Huge Car Deals, Auto Parts Now that everyone is getting LCD's those crt's are a dime a dozen I can get all I want free... so I rarely bother with fixing them... |
#8
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Ominous Ticking from Monitor
I.C. Koets wrote: My monitor (a DEC 21" CRT, older than dirt) has started to give sharp, static-discharge type audible ticks, which are accompanied by short distortions of picture and dimming. The picture distortion lasts for a refresh cycle, the dimming can take a few cycles to disappear. When I power off the screen, I hear a number of these ticks happening, one after the other, tapering off. Where do I begin to look for a solution? Google has not been much help. Try Googleing "monitor repair" because there's a lot of information about this, including from the great electronics repair FAQ: http://www.repairFAQ.org (especially read its safety information!) Also try Google Groups, namely sci.electronics.repair because there are lots of smart technicians there, including the editor of the electronics repair FAQ. There are some monitor repair forums, including at: http://www.BadCaps.net Safety warnings: #1: Don't work on the monitor unless you understand the hazards of high voltage and how to deal with them. #2: Unplug the AC power! You greatly improve the safety by leaving the AC unplugged. #3: Glass breakage may be more a hazard than electric shock. CRT monitors have almost all their weight centered about 2" from the front of the screen, meaning they can easily fall forward, so don't set the monitor upright on a soft surface, like a bed. One person did that and his monitor fell to the floor and broke the glass, but fortunately the cabinet and the laminated safety shield on the front prevented any violent implosion/explosion from shooting out shards. If you work on the monitor, either place it on a hard, perfectly horizontal tabletop with a pillow in front to catch the monitor if it falls forward, or set the monitor face-down on some padding. #4: Do not unplug the big suction cup on the side of the CRT because that's a high voltage (30,000 volts) connection and retains high voltage forever (and even if you discharge it, the charge comes back). Actually the shock harzard from this isn't that bad, but when people get shocked they often jerk their hand, either voluntarily or involuntarily, and cut it up or hit the CRT and possibly break glass (see implosion/explosion warning above). #5: It's possible to get a shock of a few hundred volts from other parts of the monitor, such as some big capacitors in the main power supply and horizontal output section (also a power supply), but those capacitors almost always discharge to zero in a few seconds. If they don't, then the shock is probably more dangerous than the higher voltage one from the CRT. #6: There is NO radiation hazard, and anybody who says otherwise either thinks your monitor was made before 1972 or is a complete idiot. The ticking sound may be from a short in a coil, such as the one around the neck of the CRT, and maybe it can be fixed by coating it with some oil-based varnish, after blowing it off with air or some electronic parts cleaner (auto parts stores, electronic supplies, Radio Shack -- get the stuff that does not leave an oily film, as tuner cleaner often does). Let any parts cleaner dry for a couple of hours, in a warm room, before varnishing. If the bad coil is the flyback transformer (the chunk of plastic with the thick cable going to that suction cup on the CRT), then you should probably junk the monitor, unless you just happen to have an identical monitor (same chassis; doesn't have to be same brand or model) with a completely different and expensive defect with it. Never overlook bad solder joints, which are often around heavy components (like that flyback transformer), hot components (big resistors, big transistors, or anything attached to a heatsink), and connectors. Those joints may be bluish or dull from heat, have hairline cracks (invisible except under magnification), or were bad from the beginning because their wire leads were dirty (each joint may look like a ball). Look for burn marks and dark areas on the circuit board. Resistors can turn brown or even crack open from heat. Electrolytic capacitors, which are aluminum cylinders covered with plastic shrink wrap, sometimes bulge or rupture on top or leak on top or bottom, but they can go bad without showing any physical signs. If you don't feel like repairing the monitor, at least try to give it to somebody who'll give it a try because most repairs aren't that difficult, and it would be a shame to waste something that may need just a simple, cheap fix. Out of 12-15 junked CRT monitors I've found on the sidewalk, I was able to repair all but one of them (a real stinker -- literally like burning plastic), and I'm no expert. |
#9
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Ominous Ticking from Monitor
Kyle wrote: Bring the monitor to a qualified lab, if the reparation cost is too much, just buy a new one. Lab? The last person I heard call a monitor repair place a "lab" was someone who thought monitors had to be repaired in clean rooms. What did you really mean to say? |
#10
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Ominous Ticking from Monitor
John Corliss wrote: CRTs, especially old ones, should be recycled at this point. They're not worth trying to save when they go out. The best way to recycle electronics is by repairing it and keeping it in operation. Other recycling is a joke and dumps lots of hazardous waste into the environment, contrary to what the recycling industry would like us to believe otherwise. Most monitor repairs are simple and cheap to people who know how to solder and operate a volt-ohm meter. Working on a CRT, as others in this thread have warned you, can get you killed if you touch a high voltage capacitor for instance. Not only that, but if you actually succeed in turning on a CRT with it's cover off, you will be exposing yourself to dangerous radiation. Seriously. You're right about the shock hazard but are completely wrong about the radiation, unless you're referring to ancient color monitors containing high voltage rectifiers consisting of vacuum tubes rather than silicon diodes, and no way will the PLASTIC cover of a monitor (usually the only cover there is) provide any protection against radiation. Where did you get your gross misinformation about the radiation, and why do you believe it? |
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